text:
Electrical Standard; Proposed Rule
[Docket No. S-108C]
Electrical Standard
AGENCY: Occupational Safety and Health Administration, Labor.
ACTION: Proposed rule.
SUMMARY: The Occupational Safety and Health Administration (OSHA) is proposing to revise the general industry electrical installation standard found in Subpart S of 29 CFR Part 1910. The Agency has determined that electrical hazards in the workplace pose a significant risk of injury or death to employees, and that the requirements in the revised standard, which draw heavily from the 2000 edition of the National Fire Protection Association's (NFPA) Electrical Safety Requirements for Employee Workplaces (NFPA 70E), and the 2002 edition of the National Electrical Code (NEC), are reasonably necessary to provide protection from these hazards. This proposed rule focuses on safety in the design and installation of electric equipment in the workplace. This revision will provide the first update of the installation requirements in the general industry electrical installation standard since 1981.
OSHA is also proposing to replace the reference to the 1971 National Electrical Code in the mandatory appendix to the powered platform standard with a reference to OSHA's electrical installation standard.
DATES: Submit written hearing requests and comments regarding this proposal, including comments on the information-collection determination described in Section XI. of the preamble (OMB Review under the Paperwork Reduction Act of 1995), by the following dates:
Hard Copy: Your hearing requests and comments must be submitted (postmarked or sent) by June 4, 2004.
Facsimile and electronic transmission: Your hearing requests and comments must be sent by June 4, 2004.
Please see the section entitled SUPPLEMENTARY INFORMATION for additional information on submitting written comments and hearing requests.
ADDRESSES: Regular mail, express delivery, hand-delivery, and messenger service: Submit three copies of hearing requests, comments, and attachments to the OSHA Docket Office, Docket No. S-108C, Room N-2625, U.S. Department of Labor, 200 Constitution Avenue, NW, Washington, DC 20210; telephone (202) 693-2350. OSHA Docket Office and Department of Labor hours of operation are 8:15 a.m. to 4:45 p.m., e.s.t.
Please note that security-related problems may result in significant delays in receiving comments and other materials by regular mail. Telephone the OSHA Docket Office at (202) 693-2350 for information regarding security procedures concerning delivery of materials by express delivery, hand delivery, and messenger service.
Facsimile: Transmit hearing requests and comments (including attachments) consisting of 10 or fewer pages by facsimile to the OSHA Docket Office at (202) 693-1648. You must include the docket number of this notice, Docket No. S-108C, in your comments.
Electronic: Submit comments electronically through the Internet at http://ecomments.osha.gov.
All comments and submissions will be available for inspection and copying in the OSHA Docket Office at the address above. Most comments and submissions will be posted on OSHA's Web page (http://www.osha.gov). Contact the OSHA Docket Office at (202) 693-2350 for information about materials not available on the OSHA Web page and for assistance in using this Web page to locate docket submissions. Because comments sent to the docket or to OSHA's Web page are available for public inspection, the Agency cautions interested parties against including in these comments personal information such as social security numbers and birth dates.
FOR FURTHER INFORMATION CONTACT: For general information and press inquiries, contact Mr. George Shaw, Office of Communications, Room N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue, NW., Washington, DC 20210; telephone (202) 693-1999. For technical inquiries, contact Ms. Belinda Cannon, Directorate of Standards and Guidance, Room N-3609, OSHA, U.S. Department of Labor, 200 Constitution Avenue, NW., Washington, DC 20210; telephone (202) 693-2083.
For additional copies of this Federal Register notice, contact OSHA, Office of Publications, U.S. Department of Labor, Room N-3101, 200 Constitution Avenue, NW., Washington, DC 20210; telephone (202) 693-1888. Electronic copies of this Federal Register notice, as well as news releases and other relevant documents, are available at OSHA's web page on the Internet at http://www.osha.gov.
This proposed rule would revise OSHA's existing standard for electrical installations, which is contained in § § 1910.302 through 1910.308 of Subpart S, with relevant definitions in § 1910.399. It would apply, as the existing standard does, to employers in general industry and in maritime employment.
OSHA undertook the project to revise Subpart S for two major reasons. First, the Agency wanted the rule to reflect the most current practice and technology in the industry. The current rule is based on a national consensus standard, the 1979 edition of Part I of NFPA 70E, entitled Standard for Electrical Safety Requirements for Employee Workplaces. That consensus standard has been updated several times since OSHA last revised its electrical installation requirements in 1981. The proposed rule being published today relies heavily on the 2000 edition of NFPA 70E. Second, in proposing this rule, OSHA is responding to requests from stakeholders that the Agency revise Subpart S so that it conforms with the most recent editions of NFPA 70E and the National Electrical Code.(1) These stakeholders argued that interested members of the public have had substantial input into the content of NFPA 70E, and that industry is complying with that standard in its current form. The revised regulation will be more flexible and efficient for stakeholders and small businesses, while maintaining needed protections for workers.
OSHA's existing electrical standard in § § 1910.302 through 1910.308 is based on the 1979 edition of NFPA 70E, which is a national consensus standard developed by a cross section of industry, labor, and other allied interests. Consensus standards like the National Electrical Code (NEC) and NFPA 70E provide nationally recognized safe electrical installation requirements. Additionally, the consensus process used in developing NFPA 70E, Part 1 of which is based on the NEC, ensures that requirements contained in that standard are current and at the forefront of electrical safety technology. Because the primary objective of this revision of Subpart S is to update the standard to recognize, and in some cases require, the most current electrical safety technology, OSHA believes that the 2000 edition of NFPA 70E should be the foundation of the proposal.
The remainder of the preamble discusses the background of the proposal; the history of Subpart S and the development of this proposal; the statutory considerations; a summary and explanation of the proposed standard; the Preliminary Economic and Regulatory Flexibility Analysis; the information collections associated with the rule; and other miscellaneous topics. The outline of the preamble is as follows:
III. History of the Rule
IV. Legal Authority
V. Summary and Explanation of the Proposed Rule
VI. Preliminary Economic and Regulatory Screening Analysis
VII. State Plan Standards
VIII. Environmental Impact Analysis
IX. Unfunded Mandates
X. Federalism
XI. OMB Review under the Paperwork Reduction Act of 1995
XII. Public Participation
XIII. List of Subjects
XIV. Authority and Signature
A. Hazards Associated With Electricity
Electricity is widely recognized as a serious workplace hazard, exposing employees to electric shock, burns, fires, and explosions. According to the Bureau of Labor Statistics, 289 employees were killed by contact with electric current in 2002.(2) Other employees have been killed or injured in fires and explosions caused by electricity.
It is well known that the human body will conduct electricity. If direct body contact is made with an electrically energized part while a similar contact is made simultaneously with another conductive surface that is maintained at a different electrical potential, a current will flow, entering the body at one contact point, traversing the body, and then exiting at the other contact point, usually the ground. Each year many workers suffer pain, injuries and death from such electric shocks.
Burns suffered in electrical accidents can be very serious. These burns may be of three basic types: electrical burns, arc burns, and thermal contact burns. Electrical burns are the result of the electric current flowing in the tissues, and may be either skin deep or may affect deeper layers (such as muscles and bones) or both. Tissue damage is caused by the heat generated from the current flow; if the energy delivered by the electric shock is high, the body cannot dissipate the heat and the tissue is burned. Typically, such electrical burns are slow to heal. Arc burns are the result of high temperatures produced by electric arcs or by explosions close to the body. If the current involved is great enough, these arcs can cause injury or can start a fire. Fires can also be created by overheating equipment or by conductors carrying too much current. Extremely high-energy arcs can damage equipment, causing fragmented metal to fly in all directions. In atmospheres which contain explosive gases or vapors or combustible dusts, even low-energy arcs can cause violent explosions. These burns are similar to burns and blisters produced by any high temperature source. Finally, thermal contact burns are those normally experienced from the skin contacting hot surfaces of overheated electric conductors, conduits, or other energized equipment. All types of burns may be produced simultaneously.
Current through the body, even at levels as low as 3 milliamperes, can also cause injuries of an indirect or secondary nature in which involuntary muscular reaction from the electric shock can cause bruises, bone fractures and even death resulting from collisions or falls.
B. Nature of Electrical Accidents
Electrical accidents, when initially studied, often appear to be caused by circumstances that are varied and peculiar to the particular incidents involved. However, further consideration usually reveals the underlying cause to be a combination of three possible factors: work involving unsafe equipment and installations; workplaces made unsafe by the environment; and unsafe work performance (unsafe acts). The first two factors are sometimes combined and simply referred to as unsafe conditions. Thus, electrical accidents can be generally considered as being caused by unsafe conditions, unsafe acts, or, in what is usually the case, combinations of the two. It should also be noted that inadequate maintenance can cause equipment or installations which were originally considered safe to deteriorate, resulting in an unsafe condition.
Some unsafe electric equipment and installations can be identified, for example, by the presence of faulty insulation, improper grounding, loose connections, defective parts, ground faults in equipment, unguarded live parts, and underrated equipment. The environment can also be a contributory factor to electrical accidents in a number of ways. Environments containing flammable vapors, liquids or gases; areas containing corrosive atmospheres; and wet and damp locations are some unsafe environments affecting electrical safety. Finally, unsafe acts include the failure to deenergize electric equipment when it is being repaired or inspected, the use of obviously defective and unsafe tools, or the use of tools or equipment too close to energized parts.
C. Protective Measures
There are various general ways of protecting employees from the hazards of electric shock, including insulation and guarding of live parts. Insulation provides an electrical barrier to the flow of current. To be effective, the insulation must be appropriate for the voltage, and the insulating material must be undamaged, clean, and dry. Guarding prevents the employee from coming too close to energized parts. It can be in the form of a physical barricade, or it can be provided by installing the live parts out of reach from the working surface. (This technique is known as "guarding by location.")
Grounding is another method of protecting employees from electric shock; however, it is normally a secondary protective measure. To keep guards or enclosures at a common potential with earth, they are connected, by means of a grounding conductor, to ground. In addition, grounding provides a path of low impedance and of ample capacity back to the source to pass enough current to operate the overcurrent devices in the circuit. If a live part accidentally comes in contact with a grounded enclosure, current flow is directed back to earth, and the circuit protective devices (for example, fuses and circuit breakers) can interrupt the circuit.
If it draws too much current, electric equipment can overheat, which can result in fires.(3) Protecting electric equipment from overcurrent helps prevent this from happening.
Designing and installing equipment to protect against dangerous arcing and overheating is also important in preventing unsafe conditions that can lead to fires, high energy electric arcs, and explosions. Employers and employees cannot usually detect improperly designed or rated equipment. Thus, OSHA relies on third- party testing and certification of electric equipment to ensure proper electrical design. This helps ensure, for example, that equipment will not overheat during normal operation and that equipment designed for use in a hazardous location will not cause a fire or explosion. It also helps ensure that equipment is appropriately rated and marked, allowing employees designing electrical installations and installing electric equipment to select equipment and size conductors in accordance with those ratings.(4) Many of the requirements in OSHA's electrical standards in turn depend on accurate ratings on equipment.
These protective measures help ensure the safe installation of electric equipment and are prescribed by the requirements presently contained in 29 CFR Part 1910, Subpart S. Addressing common unsafe conditions, these rules cover such safety considerations as guarding and insulation of live parts, grounding of equipment enclosures, and protection of circuits from overcurrent. This rulemaking would update those requirements to make them consistent with the latest edition of NFPA 70E. This revision would better protect employees by recognizing the latest techniques in electrical safety and by requiring installations to incorporate those techniques whenever necessary.
On February 16, 1972, OSHA incorporated the 1971 edition of the National Fire Protection Association's (NFPA) National Electrical Code (NEC), NFPA 70-1971, by reference as its electrical standard for general industry (37 FR 3431). The Agency followed the procedures outlined in Section 6(a) of the Occupational Safety and Health Act of 1970 (29 U.S.C. 655), which directed the Secretary to adopt existing national consensus standards as OSHA standards within 2 years of the effective date of the Occupational Safety and Health Act (OSH Act). In incorporating the 1971 NEC by reference, OSHA made the entire 1971 NEC applicable to all covered electrical installations made after March 15, 1972. For covered installations made before that date, OSHA listed about 20 provisions from the 1971 NEC that applied. No other provisions of the 1971 NEC applied to these older installations. Thus, older installations were "grandfathered" so that they did not need to meet most of the requirements in the consensus standard.
On January 16, 1981, OSHA revised its electrical installation standard for general industry (46 FR 4034). This revision replaced the incorporation by reference of the 1971 National Electrical Code with relevant requirements from Part I of the 1979 edition of NFPA 70E.(5) The revision simplified and clarified the electrical standard and updated its provisions to match the 1978 NEC (the latest edition available at the time). The standard was written to reduce the need for frequent revision and to avoid technological obsolescence. These goals were achieved--NFPA 70E had only minor changes over its initial 15 years of existence. The first substantial changes were introduced in the 1995 edition of NFPA 70E.
The latest edition of NFPA 70E, the 2000 edition, contains a number of significant revisions, including a new, alternative method for classifying and installing equipment in Class I hazardous locations (see preamble Section V. F. "Zone Classification," below). NFPA has recommended that OSHA revise its general industry electrical standards to reflect the latest edition of NFPA 70E, arguing that such a revision would provide a needed update to the OSHA standards and would better protect employees. The present proposal responds to NFPA's recommendations with regard to installation safety. It also reflects the Agency's commitment to update its electrical standards, keep them consistent with NFPA standards, and ensure that they appropriately protect employees. The Agency intends to extend this commitment by using NFPA 70E as the basis for future revisions to its electrical safety-related work practice requirements and new requirements for electrical maintenance and special equipment.
The purpose of the Occupational Safety and Health Act of 1970 (OSH Act), 29 U.S.C. 651 et seq., is "to assure so far as possible every working man and woman in the nation safe and healthful working conditions and to preserve our human resources." 29 U.S.C. 651(b). To achieve this goal, Congress authorized the Secretary of Labor to promulgate and enforce occupational safety and health standards. 29 U.S.C. 655(b) and 654(b).
A safety or health standard "requires conditions, or the adoption or use of one or more practices, means, methods, operations, or processes, reasonably necessary or appropriate to provide safe or healthful employment or places of employment." 29 U.S.C. 652(8). A standard is reasonably necessary or appropriate within the meaning of Section 652(8) if:
A significant risk of material harm exists in the workplace and the proposed standard would substantially reduce or eliminate that workplace risk;
It is technologically and economically feasible;
It is cost effective;
It is consistent with prior Agency action or supported by a reasoned justification for departing from prior Agency action;
It is supported by substantial evidence; and
In the event the standard is preceded by a consensus standard, it is better able to effectuate the purposes of the OSH Act than the standard it supersedes.
International Union, UAW v. OSHA (LOTO II), 37 F.3d 655 (D.C. Cir. 1994).
OSHA has generally considered an excess risk of 1 death per 1000 employees over a 45-year working lifetime as clearly representing a significant risk. Industrial Union Dept. v. American Petroleum Institute (Benzene), 448 U.S. 607, 646 (1980); International Union v. Pendergrass (Formaldehyde), 878 F.2d 389, 393 (D.C. Cir. 1989); Building and Construction Trades Dept., AFL-CIO v. Brock (Asbestos), 838 F.2d 1258, 1264-65 (D.C. Cir. 1988).
A standard is considered technologically feasible if the protective measures it requires already exist, can be brought into existence with available technology, or can be created with technology that can reasonably be expected to be developed. American Textile Mfrs. Institute v. OSHA (Cotton Dust), 452 U.S. 490, 513 (1981), American Iron and Steel Institute v. OSHA (Lead II), 939 F.2d 975, 980 (D.C. Cir. 1991).
OSHA generally considers a standard to be cost effective if the protective measures it requires are the least costly of the available alternatives that achieve the same level of protection. Cotton Dust, 453 U.S. at 514, n.32; International Union, UAW v. OSHA (LOTO III), 37 F.3d 655, 668 (D.C. Cir. 1994).
All OSHA standards must be highly protective, and, where practical, "expressed in terms of objective criteria and of the performance desired." LOTO III, 37 F.3d at 669. Finally, the OSH Act requires that when promulgating a rule that differs substantially from a national consensus standard, OSHA must explain why the promulgated rule is a better method for effectuating the purpose of the Act. 29 U.S.C. 655(b)(8). As discussed earlier, OSHA is using NFPA 70E as the basis for its proposed rule, with some modifications as necessary for regulatory and enforcement purposes.
Electricity has long been recognized as a serious workplace hazard exposing employees to dangers such as electric shock, electrocution, fires, and explosions. The 100-year-long history of the National Electrical Code, originally formulated and periodically updated by industry consensus, attests to this fact. The NEC has represented the continuing efforts of experts in electrical safety to address these hazards and provide standards for limiting exposure in all electrical installations, including workplaces. OSHA has determined that electrical hazards in the workplace pose a significant risk of injury or death to employees, and that this proposed standard, which draws heavily on the experience of the NEC, is reasonably necessary to provide protection from these hazards.
According to the U.S. Bureau of Labor Statistics, between 1992 and 2002, an average of 295 workers died per year from contact with electric current, and, between 1992 and 2001, an average of 4,309 workers lost time away from work because of electrical injuries.(6) Overall, there has been a downward trend in injuries and illnesses, but the percentage of decline has varied from year to year. From 1992 to 2001, the number of injuries involving days away from work decreased by 29 percent. From 1992 to 2002, the number of deaths decreased by 9 percent. This downward trend is due, in major part, to 30 years of highly protective OSHA regulation in the area of electrical installation, based on the NEC and NFPA 70E standards. The proposal would carry forward most of the existing requirements for electrical installations, with the new and revised requirements intended as fine tuning, introducing new technology along with other improvements in safety. If employers comply with the proposal, they will prevent unsafe electrical conditions from occurring. Thus, OSHA expects this downward trend in injuries to continue.
While the number of deaths and injuries associated with electrical hazards has declined, contact with electric current still poses a significant risk to employees in the workplace. This proposed rule will help further reduce the number of deaths and injuries associated with electrical hazards by providing additional requirements for installation safety and by recognizing alternative means of compliance.
A. Scope
Existing § § 1910.302 through 1910.308 of Subpart S apply to electrical installations and utilization equipment used and installed in workplaces in general industry and in shipyard employment, longshoring, and marine terminals. These sections do not apply to the following types of installations:
(1) Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles;
(2) Installations underground in mines; (7)
(3) Installations of railways for generation, transformation, transmission, or distribution of power used exclusively for operation of rolling stock or installations used exclusively for signaling and communication purposes;
(4) Installations of communication equipment under the exclusive control of communication utilities, located outdoors or in building spaces used exclusively for such installations; and
(5) Installations under the exclusive control of electric utilities for the purpose of communication or metering; or for the generation, control, transformation, transmission, and distribution of electric energy. These exempted installations must be located in buildings used exclusively by utilities for such purposes or located outdoors on property owned or leased by the utility or on public highways, streets, roads, etc., or outdoors by established rights on private property.
These exempted installations present special design considerations that are not adequately addressed in Subpart S. For example, electric power transmission and distribution installations are typically installed where unqualified persons will not have access to them, and the only employees working on them are highly trained and skilled. Additionally, public safety considerations demand that these installations be capable of quick repair when weather or equipment failure disrupt electrical service. The National Electrical Safety Code (ANSI/IEEE C2), which is developed by experts in electric power generation, transmission, and distribution, contains design and installation requirements applicable to electric power transmission and distribution systems. Section 1910.269 contains OSHA's standard for the maintenance of electric power generation, transmission, and distribution installations. While it consists mostly of work-practice requirements, it does contain several installation requirements. For example, § 1910.269(u)(4) and (v)(4) cover guarding of rooms containing electric supply equipment in electric power generating stations and substations, respectively. OSHA believes that any installation requirements for electric power generation, transmission, and distribution systems belong in § 1910.269 rather than in Subpart S.
Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles (other than mobile homes and recreational vehicles) are designed to be transportable.(8) These transportability considerations make many of the design requirements in Subpart S irrelevant, at best, or infeasible, at worst. For example, attaching the grounded circuit conductor and the equipment grounding conductor to a permanent grounding electrode on a transportable wiring system is generally not feasible. Thus, the provisions of proposed § 1910.304(g)(1), which contains requirements for grounding electrical systems, are inappropriate for the wiring of ships, watercraft, railway rolling stock, aircraft, or automotive vehicles. By contrast, however, wiring that is not a part of the wiring of the ship, watercraft, railway rolling stock, aircraft, or automotive vehicle would be covered by Subpart S, as appropriate. For example, a portable electric drill carried into the cargo area of a truck would be covered by Subpart S if it is plugged into the wiring of a service station.
In regard to ships, there has been some confusion about whether the "exemption" applies to all wiring or electrical installations brought on board a vessel during construction, overhaul, or repair, even when the wiring is supplied by shore-based electric power -- or whether it only applies to the ships' own wiring. OSHA is hereby clarifying its position.
The "exempted" types of installations in both the current and proposed standards are identical to those "exempted" by the National Electrical Code and NFPA 70E, which form the basis of both. Installations covered under the existing standard would continue to be covered under the proposal. For example, in longshoring operations and related employments, this proposal would apply to electrical installations aboard vessels only if they are shore-based as stated in § 1918.1(b)(3). Electrical installations in marine terminals are covered under Subpart S, as noted in § 1917.1(a)(2)(iv). (The marine terminals standard in Part 1917 applies to the loading, unloading, movement or other handling of cargo, ship's stores or gear within the terminal or into or out of any land carrier, holding or consolidation area, and any other activity within and associated with the overall operation and function of the terminal. This includes the use and routine maintenance of facilities and equipment and cargo transfer accomplished with the use of shore-based material handling devices. See § 1917.1(a).)
Section 1910.5 governs how the general industry electrical standards apply to shipyard employment. According to § 1910.5(c)(2), the general standards in Part 1910 apply to the extent that no industry-specific standard (such as Subpart K of Part 1926 for construction) applies to the "same condition, practice, means, method, operation, or process." Part 1915 contains few requirements related to electrical safety. Paragraph (b) of § 1915.93 contains four such requirements, for grounding of vessels, the safety of the vessel's wiring, overcurrent protection, and guarding of infrared heat lamps. Section 1915.92 contains provisions on electric lighting, and § 1915.132 contains requirements on portable electric tools. Section 1915.181 contains electrical safety-related work practices for deenergizing electric circuits and protecting employees against contact with live parts during electrical work. In addition, Part 1915 contains several other miscellaneous electrical safety-related work practices and electrical design requirements. These provisions continue to apply in lieu of any corresponding requirements in Subpart S of Part 1910. Conversely, where there is no specific standard for shipyard employment in Part 1915, Subpart S of Part 1910 applies.(9)
As noted earlier, Subpart S does not cover installations in ships, but it does cover installations used on ships if the installation is shore-based (that is, not part of the vessel's internal electrical system). Thus, § 1910.303(g)(2) (guarding live parts) applies to the wiring of the shipyard and to any wiring taken onto the ship when it is supplied by the shipyard wiring. It does not apply to the ship's wiring. The proposed rule does not change this scope of coverage. However, OSHA invites comments on whether it needs to clarify this coverage further.
B. Grandfather Clause
The proposal, as does the current rule, exempts older electrical installations from meeting some of the provisions of the Design Safety Standards for Electrical Systems (that is, § § 1910.302 through 1910.308). The extent to which OSHA's electrical installation standard applies depends on the date the installation was made. Older installations must meet fewer requirements than newer ones. The proposal's grandfathering of older installations, contained in paragraph (b) of proposed § 1910.302, is patterned after the current standard's grandfather provisions in existing § 1910.302(b). Most of the new provisions contained in the proposed rule would only apply prospectively, to installations made after the effective date of the final rule.
The following paragraphs explain proposed § 1910.302(b) in the following order: paragraph (b)(1), requirements applicable to all installations; paragraph (b)(4), requirements applicable only to installations made after the effective date of the revised standard; paragraph (b)(3), requirements applicable only to installations made after April 16, 1981; and paragraph (b)(2), requirements applicable only to installations made after March 15, 1972.
Requirements applicable to all installations. Paragraph (b)(1) of proposed § 1910.302 contains a list of provisions that would apply to all installations, regardless of when they were designed or installed. The few requirements in this short list are so essential to employee safety that even the oldest electrical installations must be modified, if necessary, to meet them. The list is unchanged from the current standard, except for the addition of the zone classification system and a documentation requirement from proposed § 1910.307. As discussed in more detail later in this section of the preamble, the only substantial new provisions being proposed in § 1910.307 are: (1) New requirements in § 1910.307(g) pertaining to electric equipment installed in Class I hazardous locations if the employer chooses to use the zone classification system and (2) a new requirement in § 1910.307(b) for employers to document the extent of each hazardous location. This second provision applies to older installations only if the employer is using the zone classification system.
The new requirements pertaining to zone classification in proposed § 1910.307(g) provide employers with an alternative installation method that the current standard does not permit.(10) Thus, applying these provisions to older installations would give employers greater flexibility without imposing any new costs.
Paragraph (b) of § 1910.307 proposes a new requirement that employers document areas designated as hazardous (classified) locations. This requirement would ensure that the employer has records of the extent and classification of each such area. The documentation would help employers determine what type of equipment was needed in these locations and would inform employees of the need for special care in the maintenance of the electric equipment installed there. OSHA has carefully considered the need to document these areas and has tried to balance that need with the extensive burden that would be placed on employers who would have to survey and document their existing hazardous locations.
The current standard's division classification system has been in place for many years, and most employers and inspection authorities are familiar with the boundaries for Class I, Division 1 and Class I, Division 2 locations. An employee servicing equipment in a Class I, Division 1 or 2 location can obtain this information relatively easily even if the employer has not documented the boundaries. Accordingly, OSHA believes that the benefit of documenting existing hazardous locations installed using the division classification system would be minimal. Therefore, for employers using the division system, OSHA is proposing to require documentation of boundaries only for new installations made after the effective date of the standard. Employers would not need to document existing division-classified systems.
On the other hand, the zone classification system is relatively new. Most employers are not familiar with this system and have little experience determining how to draw the boundaries between the three zones. Relatively few NFPA or industry standards provide specifications for placing those boundaries. Furthermore, the existing OSHA electrical standard recognizes only installations made in accordance with the division classification system, not the zone classification system. Any existing installation made under the zone system is technically out of compliance with OSHA's existing standard. However, because the NEC represents standard industry practice, existing zone system installations will almost certainly have been installed in accordance with an edition of the NEC that recognizes the zone classification system (the 1999 and 2002 editions). These editions of the NEC explicitly require documentation of hazardous locations. Thus, an employer with an existing installation made under the zone classification system should already have the documentation required by § 1910.307(b). Therefore, OSHA believes that the benefits of having documentation for existing zone-classified installations justify the small burden that would be placed on employers. For these reasons, OSHA is proposing to apply the documentation requirement to all hazardous location installations made under the zone classification system. This will provide employers, employees, and OSHA with information critical for determining which equipment is suitable in a given hazardous location.
Requirements applicable only to installations made after the effective date of the final rule. Paragraph (b)(4) of proposed § 1910.302 would make the following provisions applicable only to installations made or overhauled (11) after the effective date of the final rule:
§ 1910.303(f)(4) -- Disconnecting means and circuits -- Capable of accepting a lock
§ 1910.303(f)(5) -- Disconnecting means and circuits -- Marking for series combination ratings
§ 1910.303(g)(1)(iv) and (g)(1)(vii) -- 600 Volts, nominal, or less -- Space about electric equipment
§ 1910.303(h)(5)(vi) -- Over 600 volts, nominal -- Working space and guarding
§ 1910.304(b)(1) -- Branch circuits -- Identification of multiwire branch circuits
§ 1910.304(b)(3) -- Branch circuits -- Identification of ungrounded conductors
§ 1910.304(b)(4)(i) -- Branch circuits -- Ground-fault circuit interrupter protection for personnel
§ 1910.304(f)(2)(i)(A), (f)(2)(i)(B) (but not the introductory text to § 1910.304(f)(2)(i), and (f)(2)(iv)(A) -- Overcurrent protection -- Overcurrent protection, feeders and branch circuits for over 600 volts, nominal
§ 1910.305(a)(3)(v) -- Wiring methods -- Cable trays
§ 1910.305(c)(3)(ii) -- Switches -- Connection of switches
§ 1910.305(c)(5) -- Switches -- Grounding
§ 1910.306(a)(1)(ii) -- Electric signs and outline lighting -- Disconnecting means
§ 1910.306(c)(4) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Operation
§ 1910.306(c)(5) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Location
§ 1910.306(c)(6) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Identification and signs
§ 1910.306(c)(7) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Single-car and multicar installations
§ 1910.306(j)(1)(iii) -- Swimming pools, fountains, and similar installations -- Receptacles
§ 1910.306(k) -- Carnivals, circuses, fairs, and similar events
§ 1910.308(a)(5)(v) and (a)(5)(vi)(B) -- Systems over 600 volts, nominal -- Interrupting and isolating devices
§ 1910.308(a)(7)(vi) -- Systems over 600 volts, nominal -- Tunnel installations
§ 1910.308(b)(3) -- Emergency power systems -- Signs
§ 1910.308(c)(3) -- Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits -- Separation from conductors of other circuits
§ 1910.308(f) -- Solar photovoltaic systems
These provisions are based on requirements that have been added to the National Electrical Code since the 1978 edition. OSHA has never required employers to comply with these requirements, and the Agency believes that the modest increase in employee protection that would result from compliance with them would not be worth the substantial expense that employers would incur if existing installations had to be retrofitted to conform to those provisions. On the other hand, employers would incur minimal costs to achieve this increase in protection if they only needed to assure that new installations comply with the listed provisions. In local jurisdictions requiring compliance with the NEC, there should be no additional costs involved, because the installations would already conform to the new OSHA requirements. The Agency believes that even in other jurisdictions, the vast majority of installations already comply with the latest edition of the NEC, because compliance with the latest Code is standard industry practice.
OSHA is considering making the new requirements in revised Subpart S effective 90 days after the final rule is published in the Federal Register. The Agency requests comments on whether this provides sufficient time to implement the changes required by the revised standard. It should be noted that applying new provisions only to new installations is the same approach that OSHA took in promulgating the current version of Subpart S in 1981. The Agency found that this approach was successful and has no indication that it was unduly burdensome or insufficiently protective.
There are also many provisions in proposed Subpart S that are not contained in the existing standard but cannot be considered totally "new" provisions. Most of these "new" requirements were actually contained in the 1971 NEC. Table 1 lists these "new" provisions and denotes their counterparts in the 1971 NEC. From March 15, 1972, until April 16, 1981, Subpart S incorporated the 1971 NEC by reference in its entirety. Accordingly, OSHA required employers to comply with every requirement in the 1971 NEC for any new installation made between those dates and for any replacement, modification, repair, or rehabilitation made during that period. The current standard, which became effective on April 16, 1981, omitted many of the detailed provisions of the NEC because they were already addressed by the more general requirements that were contained in the OSHA standard. For example, OSHA did not carry forward 1971 NEC Section 110-11, which required equipment to be suitable for the environment if it is installed where the environment could cause deterioration. However, the requirement for equipment to be suitable for the location in which it was installed is implicit in the more general requirements in existing § 1910.303(a) that equipment be approved and in existing § 1910.303(b)(2) that equipment be installed in accordance with any instructions included in its listing or labeling. (Equipment that is not suitable for installation in deteriorating environments, such as wet or damp locations, will include instructions warning against such installation. These instructions are required by the nationally recognized laboratory listing or labeling the product.)
Even though OSHA has not required employers to maintain their installations in compliance with these older provisions, the Agency believes that employers' installations actually do comply with those requirements. The vast majority of employers are following the entire National Electrical Code applicable to their installations, as noted in the Economic Analysis section of this preamble.(12) For these reasons, OSHA is not proposing to exempt installations made after March 15, 1972, from meeting any provision listed in Table 1 and is not including any of these provisions in § 1910.302(b)(4) (the list of provisions that apply only to new installations). The Agency invites public comment on whether this approach is reasonable.
Table 1.--"New" Provisions Contained in 1971 NEC(13)
Proposed provision Equivalent 1971 NEC section Subject
§ 1910.303(b)(3)
(b)(4)
(c)(1)
(e)(1)(iv)
(f)(1)(ix)
(f)(2), except for
(f)(2)(i)(A), (f)(2)(i)(B),
and (f)(2)(iv)(A)
§ 190.305(a)(4)(ii)
(b)(1)(iii)
(b)(2)(ii)
(e)(1)
(h)(3)
(j)(2)(i)
(j)(2)(iv) through (j)(2)(vii)
(j)(3)(ii)
(j)(3)(iii)
(j)(3)(iv)
(j)(6)(ii)(A)
(j)(6)(ii)(B)
§ 1910.306(c)(3)
(c)(10)
(d)(1)
(g)(1)(iii)
(g)(1)(vi)
§ 1910.308(a)(2)
(a)(3)(i)
(a)(4)
(a)(5)(ii)
(a)(5)(iii) and (a)(5)(iv)
(a)(5)(vi), but not (a)(5)(vi)(B)
(a)(5)(vii)
(b)(2) 110-20
110-4(a) and (d)
210-21(b)
230-70(c)
410-52(d)
422-30(a)
460-8(c)(4)
680-20(a)(4)
700-14 Insulation integrity.
Interrupting rating.
Circuit impedance and other characteristics.
Deteriorating agents.
Mechanical execution of work.
Mounting and cooling of equipment.
Electrical connections, general.
Branch circuits, receptacles and cord connectors.
Branch circuits, outlet devices.
Branch circuits, cord connections.
Services, disconnecting means.
Overcurrent protection, 600 volts, nominal, or less, circuit breaker ratings.
Overcurrent protection, feeders and branch circuits over 600 volts, nominal.
Open wiring on insulators, support.
Conductors entering cabinets, boxes, and fittings, securing conductors.
Fixture canopy or pan installed in a combustible wall or ceiling.
Airspace for enclosures installed in wet or damp locations.
Portable cables, grounding conductors.
Receptacles, cord connectors, and attachment plugs; no exposed energized parts.
Receptacles installed in wet or damp locations.
Appliances, disconnecting means.
Appliances, nameplates.
Appliances, marking to be visible after installation.
Capacitor switches.
Capacitor disconnecting means.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts; type of disconnecting means.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts; motor controllers.
Arc welders, disconnecting means.
Induction and dielectric heating equipment, detachable panels used for access to live parts.
Induction and dielectric heating equipment, ampere rating of disconnecting means.
Swimming pools, fountains, and similar installations, underwater fixtures facing upwards.
Systems over 600 volts, nominal; open installations of braid- covered insulated conductors.
Systems over 600 volts, nominal; insulation shielding terminations.
Systems over 600 volts, nominal; moisture or mechanical protection for metal-sheathed cables.
Systems over 600 volts, nominal; interrupting and isolating devices; guarding and indicating.
Systems over 600 volts, nominal; interrupting and isolating devices; fuses.
Systems over 600 volts, nominal; interrupting and isolating devices; fused cutouts.
Systems over 600 volts, nominal; interrupting and isolating devices; load interrupter switches.
Systems over 600 volts, nominal; interrupting and isolating devices; means for isolating equipment.
Emergency systems, emergency illumination.
In addition, OSHA is not including in the list of new provisions in proposed § 1910.302(b)(4) any proposed provision that merely provides an alternative means of compliance for an existing requirement. For example, as noted earlier, § 1910.307(g) provides alternative requirements for installations in hazardous (classified) locations based on the zone classification system rather than the division classification system that is required under the existing standard. Such requirements accept alternative installation techniques recognized as being equally protective by the NEC and NFPA 70E, and there is no need to limit them to new installations.
OSHA also believes that there is no need to grandfather requirements that apply only to temporarily installed equipment and wiring.(14) The few new requirements applying to temporarily installed equipment and wiring have been in the National Electrical Code since at least 1999 and, in most cases, since before that. Employers should already be in compliance with such requirements since the temporary installations almost certainly were put into place well after 1999. For example, proposed § 1910.304(b)(4)(ii) contains requirements for providing ground-fault circuit interrupter protection for temporary wiring installations that are used during maintenance, remodeling, or repair of buildings, structures, or equipment or during similar activities. Temporary wiring installations used for any of these purposes were likely to have been installed well after 1999. An employer who is complying with the 1999 or later edition of the NEC will already be complying with this provision of the proposal. Even employers who are not complying with recent versions of the NEC for temporary wiring will face only the minimal cost of providing ground-fault circuit interrupters; no changes would need to be made to any existing permanent wiring, which might involve considerably more costs. The Agency requests comments on whether any new requirements applying only to temporarily installed equipment or wiring should also be listed in § 1910.302(b)(4), and why.
Additionally, OSHA recognizes that, in a proposed standard this extensive, some new requirements might have been overlooked and some subtle changes in existing requirements might have unanticipated consequences. Therefore, the Agency requests comments on whether there are any other new or revised requirements in the proposal that should not apply to existing installations.
Requirements applicable only to installations made after April 16, 1981. Paragraph (b)(3) of § 1910.302 lists requirements that apply only to installations made after April 16, 1981. This proposed paragraph carries forward essentially the same list as is currently in § 1910.302(b)(3). No provisions have been added to or removed from the list.
Requirements applicable only to installations made after March 15, 1972. Paragraph (b)(2) of existing § 1910.302 requires all installations made after March 15, 1972, and every major replacement, modification, repair, or rehabilitation made after that date to meet all the installation requirements in Subpart S except for those listed in § 1910.302(b)(3) and (b)(4). A note following existing § 1910.302(b)(2) indicates that "major replacements, modifications, repairs, or rehabilitations" include work similar to that involved when a new building or facility is built, a new wing is added, or an entire floor is renovated.
Paragraph (b)(2) of proposed § 1910.302 would require all installations built or overhauled after March 15, 1972, to comply with all of the requirements of § § 1910.302 through 1910.308, except as provided in § 1910.302(b)(3) and (b)(4). As discussed earlier, these latter two paragraphs limit the application of newer provisions of Subpart S to installations made during later periods.
In the proposal, OSHA is introducing the term "overhaul" to include the types of activities that would trigger compliance with the otherwise grandfathered provisions of Subpart S for older installations. "Overhaul" is defined as follows:
Overhaul means to perform a major replacement, modification, repair, or rehabilitation similar to that involved when a new building or facility is built, a new wing is added, or an entire floor is renovated.
Thus, this new term, which is based on language in current Subpart S, incorporates all the elements of "major replacement, modification, or rehabilitation" in the text of existing § 1910.302(b)(2) and in the note following that provision. OSHA believes that the proposed language will simplify the standard without making any substantive change to the way in which Subpart S applies to older installations.
C. Summary of Changes in § § 1910.303 Through 1910.308 The Distribution Table for Subpart S lists all the provisions and sections from § § 1910.303 through 1910.308 of the electrical standard. This table summarizes any proposed changes being made to the standard that involve grammatical edits, additions, removals, and paragraph numbers. There are places in the standard where no substantial change is made. Most of the changes are editorial in nature. Some of the requirements would be removed because the material is considered outdated. However, the substantive changes to be made to the standard will be discussed in further detail following this section.
Distribution Table
OLD -- section NEW -- section Description of changes and rationale
See the note at the end of the table
§ 1910.303 General
1910.303(a)
1910.303(b)(1), introductory text.
1910.303(b)(1)(i)
1910.303(b)(1)(ii)
1910.303(b)(1)(iii)
1910.303(b)(1)(iv)
1910.303(b)(1)(v)
1910.303(b)(1)(vi)
1910.303(b)(1)(vii)
1910.303(b)(2)
1910.303(c)
1910.303(d)
1910.303(e)
1910.303(f)
1910.303(g)(1), introductory text.
1910.303(g)(1)(i)
1910.303(g)(1)(ii)
1910.303(g)(1)(iii)
1910.303(g)(1)(iv)
1910.303(g)(1)(v)
1910.303(g)(1)(vi)
1910.303(h)(1)
1910.303(h)(2), introductory text.
1910.303(h)(2)(i)
1910.303(h)(2)(ii)
1910.303(h)(3)(iii)
§ 1910.304 Wiring design and protection.
1910.304(a)(1)
1910.304(c), introductory text.
1910.304(c)(1)
1910.304(d)(1)(i)
1910.304(d)(1)(ii)
1910.304(d)(2)
1910.304(e)(1), introductory text
1910.304(e)(1)(i)
1910.304(e)(1)(ii)
1910.304(e)(1)(iii)
1910.304(e)(1)(iv)
1910.304(e)(1)(v)
1910.304(e)(1)(vi)(A)
1910.304(e)(1)(vi)(B)
1910.304(e)(1)(vi)(C)
1910.304(e)(2)
1910.304(f), introductory text.
1910.304(f)(1), introductory text.
1910.304(f)(1)(i)
1910.304(f)(1)(ii)
1910.304(f)(1)(iii)
1910.304(f)(1)(iv)
1910.304(f)(1)(v)
1910.304(f)(2)
1910.304(f)(5)(vi)
§ 1910.305 Wiring methods, components, and equipment for general use.
1910.305(a), introductory text. 1910.305(a)(1)(i)
1910.305(a)(1)(ii)
1910.305(a)(2), introductory text.
1910.305(a)(2)(i), introductory text. 1910.305(a)(2)(i)(A)
1910.305(a)(2)(i)(B
1910.305(a)(2)(i)(C) 1910.305(a)(2)(ii)
1910.305(a)(2)(iii)(A)
1910.305(a)(2)(iii)(B)
1910.305(a)(2)(iii)(C) 1910.305(a)(2)(iii)(D)
1910.305(a)(2)(iii)(E)
1910.305(a)(2)(iii)(F)
1910.305(a)(2)(iii)(G)
1910.305(a)(3)(i)(A) 1910.305(a)(3)(i)(B)
1910.305(a)(3)(i)(C)
1910.305(a)(4)(i)
1910.305(a)(4)(iii)
1910.305(a)(4)(iv)
1910.305(a)(4)(v)
1910.305(h)
1910305(i)(1)
1910.305(i)(2)
1910.305(j)(1)(i)
1910.305(j)(1)(ii)
1910.305(j)(1)(iii)
1910.305(j)(1)(iv)
1910.305(j)(4)
1910.305(j)(4)(ii)(A)
1910.305(j)(4)(ii)(B)
1910.305(j)(4)(ii)(C)
1910.305(j)(4)(ii)(D)
1910.305(j)(4)(ii)(E)
1910.305(j)(4)(ii)(F)
1910.305(j)(4)(iv)(A)
1910.305(j)(4)(iv)(B)
1910.305(j)(5)(i)(iv)
1910.305(j)(5)(i)(v)
1910.305(j)(5)(i)(vi)
1910.306(g)(3)
1910.306(h)(7)(iv)
§ 1910.307 Hazardous (classified) locations
§ 1910.307(a)
1910.307(b), introductory text.
1910.307(b)(2)(i)(ii), introductory text.
1910.307(b)(2)(ii)(A)
1910.307(b)(2)(ii)(B)
1910.307(b)(2)(ii)(C)
1910.307(b)(2)(ii)(D)
1910.307(b)(3), Note.
§ 1910.308 Special systems.
1910.308(a), introductory text.
1910.308(c)(1), introductory text.
1910.308(c)(1)(i)
1910.308(c)(1)(ii)
1910.308(c)(1)(iii)
1910.308(d)(2), introductory text.
1910.308(e)(5)(iii) § 1910.303 General 1910.303(a)
1910.303(b)(1)(i) 1910.303(b)(1)(ii) 1910.303(b)(1)(iii)
1910.303(b)(1)(iv) 1910.303(b)(1)(v) 1910.303(b)(1)(vi) 1910.303(b)(1)(vii 1910.303(b)(1)(viii) 1910.303(b)(2) 1910.303(b)(3)
1910.303(c)(3)(i) 1910.303(c)(3)(ii)
1910.303(f)(1) 1910.303(f)(2) 1910.303(f)(3)
1910.303(g)(1), introductory text. 1910.303(g)(1)(i)
Table S-1, Note 3.
1910.303(g)(1)(ii) 1910.303(g)(1)(iii) 1910.303(g)(1)(iv)
1910.303(g)(1)(i)(B)
1910.303(g)(1)(vii)
1910.303(g)(2)(i) 1910.303(g)(2)(ii) 1910.303(g)(2)(iii) 1910.303(h)(1) 1910.303(h)(2)(i) 1910.303(h)(2)(ii)
1910.303(h)(2)(iii) 1910.303(h)(2)(iv) 1910.303(h)(2)(v) 1910.303(h)(5)(iii)
1910.303(h)(3) 1910.303(h)(5)(i) Table S-2, Note 3.
1910.303(h)(5)(iv) 1910.303(h)(5)(v)
1910.303(h)(4)(ii) 1910.303(h)(5)(ii)
1910.303(h)(5)(vi)
§ 1910.304 Wiring design and protection
1910.304(a)(2) 1910.304(a)(3) 1910.304(b)(1)
1910.304(d) 1910.304(e)(1)(i) 1910.304(e)(1)(ii) 1910.304(e)(1)(iii)
1910.304(e)(2) 1910.304(f)(1), introductory text.
1910.304(f)(1)(i) 1910.304(f)(1)(ii) 1910.304(f)(1)(iii)
1910.304(f)(1)(iv) 1910.304(f)(1)(v)
1910.304(f)(1)(vi) 1910.304(f)(1)(vii) 1910.304(f)(1)(viii)
1910.304(f)(1)(ix)
1910.304(g), introductory text.
1910.304(g)(1)(i) 1910.304(g)(1)(ii) 1910.304(g)(1)(iii) 1910.304(g)(1)(iv)
1910.304(g)(3) 1910.304(g)(4) 1910.304(g)(5)(i) 1910.304(g)(5)(ii) 1910.304(g)(5)(iii) 1910.304(g)(5)(iv) 1910.304(g)(5)(v)
1910.304(g)(5)(vi) 1910.304(g)(5)(vii)
1910.304(g)(7) 1910.304(g)(8), introductory text.
1910.304(g)(8)(i) 1910.304(g)(8)(ii)
1910.305(a)(1)(iii) 1910.305(a)(2), introductory text.
1910.305(a)(2)(i), introductory text.
1910.305(a)(2)(i)(A)
1910.305(a)(2)(i)(B) 1910.305(a)(2)(ii)
1910.305(a)(2)(vi) 1910.305(a)(2)(vii) 1910.305(a)(2)(viii)
1910.305(a)(2)(ix)
1910.305(a)(2)(x) 1910.305(a)(2)(xi)
1910.305(a)(3)(i) 1910.305(a)(3)(ii)
1910.305(a)(3)(iv) 1910.305(a)(3)(v)
1910.305(a)(3)(vi) 1910.305(a)(4)(i) 1910.305(a)(4)(ii)
1910.305(a)(4)(iii) 1910.305(a)(4)(iv) 1910.305(a)(4)(v) 1910.305(b)(1)(i)
1910.305(b)(2)(i) 1910.305(b)(2)(ii)
1910.305(c)(1) 1910.305(c)(2) 1910.305(c)(3)(i) 1910.305(c)(3)(ii)
1910.305(d)(1) 1910.305(d)(2) 1910.305(d)(3) 1910.305(e)(1)
1910.305(g)(2)(iii) 1910.305(h)
1910.305(h)(1) 1910.305(h)(2) 1910.305(h)(3) 1910.305(h)(6) 1910.305(h)(7) 1910.305(h)(8) 1910.305(h)(4)
1910.305(i)(2) 1910.305(i)(3)
1910.305(j)(1)(i) 1910.305(j)(1)(ii)
1910.305(j)(1)(iv) 1910.305(j)(2)(i)
1910.305(j)(2)(ii) 1910.305(j)(2)(iii)
1910.305(j)(2)(iv) 1910.305(j)(2)(v)
1910.305(j)(2)(vi) 1910.305(j)(2)(vii)
1910.305(j)(4)(v)
1910.305(j)(4)(vi)
1910.305(j)(4)(vii)
1910.305(j)(4)(viii) 1910.305(j)(5)(i) 1910.305(j)(5)(ii) 1910.305(j)(5)(iii) 1910.305(j)(5)(i)(iv)
1910.306(h), introductory text.
1910.306(h)(2) 1910.306(h)(3)
1910.306(j), introductory text.
1910.306(j)(2)(ii) 1910.306(j)(3) 1910.306(j)(4)(i) 1910.306(j)(4)(ii) 1910.306(j)(4)(iii)
1910.306(k)
§ 1910.307 Hazardous (classified) locations 1910.307(a)
1910.307(b)
1910.307(c)(2)(ii), introductory text. 1910.307(c)(2)(ii)(A)
1910.307(c)(2)(ii)(B)
1910.307(c)(2)(ii)(C)
1910.307(c)(2)(ii)(D)
1910.307(c)(2)(ii)(E)
1910.307(c)(3), Note
1910.307(g)
§ 1910.308 Special systems
1910.308(a)(5)(vi)
1910.308(a)(5)(vii)
1910.308(a)(6)(ii) 1910.308(a)(7), introductory text
1910.308(a)(7)(vii) 1910.308(a)(7)(viii) 1910.308(b), introductory text.
1910.308(b)(1) 1910.308(b)(2)
1910.308(c)(1)(i) 1910.308(c)(1)(ii) 1910.308(c)(1)(iii 1910.308(c)(2) 1910.308(c)(3)
1910.308(d)(2)(i) 1910.308(d)(2)(ii)
1910.308(d)(3)(i) 1910.308(d)(3)(ii) 1910.308(d)(3)(iii) 1910.308(d)(3)(iv)
1910.308(e), introductory text.
1910.308(e)(2)(i) 1910.308(e)(2)(ii) 1910.308(e)(2)(iii) 1910.308(e)(2)(iv) 1910.308(e)(3) 1910.308(e)(4)(i) 1910.308(e)(4)(ii) 1910.308(e)(4)(iii) 1910.308(f)
No substantive change. A reference to the § 1910.399 definition of "approved" is added for clarification.
No substantive change.
**Adds wire-bending and connection space to the list of things to consider when judging equipment.
**Adds a requirement for completed wiring to be free from short circuits and grounds other than those required in the standard.
**Adds requirements for equipment intended to interrupt current to have adequate interrupting ratings.
**Adds requirements for the coordination of overcurrent protection for circuits and equipment.
**Adds a requirement for conductors and equipment to be identified for the purpose when installed in an environment containing deteriorating agents.
**Adds requirements for installing electric equipment in a neat and workmanlike manner.
**Adds requirements for equipment to be mounted securely and to allow for proper cooling.
**Adds requirements to ensure that electrical connections are secure and electrically safe.
**Adds requirements for connections at terminals.
**Adds requirements for the identification of terminals intended for connection to more than one conductor or to aluminum.
**Adds a requirement that wire connectors or splicing means installed on directly buried conductors be listed for such use.
No substantive change. (Individual requirements are placed in separate paragraphs.)
Adds a requirement for disconnecting means required by Subpart S to be capable of accepting a lock. This provision is added to make the Subpart S requirements on disconnecting means consistent with § 1910.147(c)(2)(iii) , which requires energy isolating devices (a generic term, which includes electrical disconnecting means) to be designed to accept a lockout device.
**Adds marking requirements for series combination ratings of circuit breakers or fuses.
**The proposal revises the language to clarify how wide and high the clear space must be.
**Adds a requirement for a second entrance on equipment rated 1200 amperes under certain conditions.
**Reduced the minimum width of the clear space to 762 mm.
**Adds a prohibition against controlling illumination for working spaces by automatic means only.
**Increased the minimum height of the working space from 1.91m to 1.98m for new installations.
** Adds requirements for switchboards, panelboards, and distribution boards installed for the control of light and power circuits, and motor control centers to be installed in dedicated space and to be protected against damage.
**The minimum height of fences restricting access to electrical installations over 600 V is reduced from 2.44 m to 2.13 m.
**1. The proposal organizes these requirements on the basis of whether the installations are indoors or outdoors. (The existing standard organizes them on the basis of whether or not the installations are accessible to unqualified employees.)
2. Adds requirements intended to prevent tampering by the general public.
3. Removes requirement to lock underground box covers weighing more than 45.4 kg.
**The distances in Table S-2 for the depth of working space in front of electric equipment are increased for new installations to match the distances in NFPA 70E-2000.
**The distances in Table S-3 for the elevations of unguarded live parts are increased for new installations to match the distances in NFPA 70E-2000.
**The existing standard requires a second entrance to give access to the working space about switchboards and control panels over 600 V if the equipment exceed 1.22 m in width if it is practical to install a second entrance. The proposal requires an entrance on each end of switchboards and panelboards exceeding 1.83 m unless the working space permits a continuous and unobstructed way of travel or the working space is doubled. In addition, the proposal requires the lone entrance permitted under either of these exceptions to be at least the distance specified in Table S-2 from exposed live parts.
**Adds requirements for equipment operating at 600 V or less installed in rooms or enclosures containing exposed live parts or exposed wiring operating at more than 600 V.
**Adds requirements limiting the installation of pipes or ducts that are foreign to electrical installation operating at more than 600 V.
**Adds requirements for the identification of multiwire branch circuits.
**Adds requirements that receptacles installed on 15- and 20-ampere circuits be of the grounding type and that grounding-type receptacles be installed in circuits within their rating.
**Adds a requirement for grounding contacts on receptacles to be effectively grounded.
**Adds requirements on the methods used to ground receptacles and cord connectors.
**Adds requirements on the replacement of receptacles.
**Adds a requirement that receptacles installed on branch circuits having different voltages, frequencies, or types of current be noninterchangeable.
**Adds requirements on identification of ungrounded conductors on different systems.
**Adds requirements for ground fault circuit interrupter protection.
No significant change.
**Adds requirements for ratings of lampholders.
**Adds requirements for ratings of receptacles.
**Adds requirements for receptacles to be installed wherever cords with attachment plugs are used.
No significant change. (The requirements in existing paragraph (c)(5) are placed in a separate paragraph (d).)
**Adds a requirement for the separation of conductors on poles.
Increases the minimum clearances for new installations of open conductors and service drops to match those in NFPA 70E-2000.
No substantive change. (The proposal clarifies that paragraph (c)(2) applies to platforms, projections, or surfaces from which runs of open conductors can be reached.)
**Adds restrictions for installing overhead service conductors near building openings through which materials may be moved.
**Adds an exception to the minimum clearance requirement for conductors attached to the side of a building. (The proposal also clarifies that paragraph (c)(2) applies to roof surfaces that are subject to pedestrian or vehicular traffic.)
**Adds a requirement for service disconnecting means to be suitable for the prevailing conditions.
**The types of circuits that are allowed to have a single switch disconnect for multiple fuses are now specified in the standard.
**Adds a requirement to clarify that handles of circuit breakers and similar moving parts also need to be guarded so that they do not injure employees.
**Adds circuit breakers used on 277-volt fluorescent lighting circuits to the types of breakers required to be marked "SWD."
**Adds a requirement to clarify ratings of circuit breakers.
**Adds specific requirements on how to protect feeders and branch circuits energized at more than 600 volts.
No substantive change. (The specific voltage ratings in existing paragraphs (g)(1)(iv)(B) and (g)(1)(iv)(C) are being removed. However, this is not a substantive change as those are the voltages used in the described systems.)
**Adds an exception to the requirement to ground systems for high-impedance grounded systems of 480 V to 1000 V under certain conditions.
**Removed. The hazard is addressed in proposed § 1910.304(a)(1)(i), which requires conductors used as grounded conductors to be identifiable and distinguishable from other conductors.
**Relaxes requirements for grounding portable and vehicle mounted generators so that the requirements match those in OSHA's Construction Standards (§ 1926.404(f)(3)
**The exceptions for grounding fixed equipment operating at more than 150 V are extended to all fixed electric equipment regardless of voltage. Also, the proposal includes a new exception for double-insulated equipment.
**Adds the following equipment to the list of cord- and plug-connected equipment required to be grounded: stationary and fixed motor- operated tools and light industrial motor-operated tools.
**Adds frames and tracks of electrically operated hoists to the list of nonelectrical equipment required to be grounded.
**Adds a requirement that equipment be bonded so as to provide adequate fault-current- carrying capability. Also, clarifies that nonconductive coatings need to be removed unless the fittings make this unnecessary.
**Adds an exception to the bonding requirement for the reduction of electrical noise.
No substantive change. Removes the provision allowing temporary wiring to be of a class less than permanent wiring per the 2002 NEC. The change has no substantive effect because temporary wiring is required to meet the same requirements regardless of the deleted language. (Both the proposal and the existing standard contain the following requirement: "Except as specifically modified in this paragraph, all other requirements of this subpart for permanent wiring shall apply to temporary wiring installations.")
Removes demolition from the list of activities for which temporary wiring is permitted . Demolition is one form of construction work, which is not covered by the Subpart S installation requirements.
**Adds emergencies to the list of activities for which temporary wiring is permitted.
**Clarifies that temporary wiring must be removed when the project or purpose for which it was used has been completed.
**Feeders may now only be run as single insulated conductors when accessible to qualified employees only and used for experiments, development work, or emergencies. (Individual requirements are placed in separate paragraphs.)
**Adds a requirement that disconnecting means for a multiwire circuit simultaneously disconnect all ungrounded conductors of the circuit.
**This provision no longer allows installing fixtures or lampholders more than 2.1 meters above the working surface as a means of guarding. Also, the proposal adds a requirement for grounding metal- case sockets.
**Adds requirements for cable assemblies and flexible cords and cables to be adequately supported.
**Adds several types of cables and single insulated conductors to the list of types permitted in industrial establishments.
**Adds a requirement limiting the use of metallic cable trays as an equipment grounding conductor.
**Adds a requirement limiting the use of nonmetallic cable trays.
**Adds specific support requirements for conductors smaller than No. 8.
**Adds requirements for supporting cables entering cabinets, cutout boxes, and meter sockets.
**Adds a requirement for any exposed edge of a combustible ceiling finish at a fixture canopy or pan to be covered with noncombustible material.
**Adds a requirement for load terminals on switches to be deenergized when the switches are open except under limited circumstances.
**Adds a specific requirement for flush-mounted switches to have faceplates that completely cover the opening and that seat against the finished surface.
**Adds a requirement to ground faceplates for snap switches.
**Adds a requirement for metallic cabinets, cutout boxes, fittings, boxes, and panelboard enclosures installed in damp or wet locations to have an air space between the enclosure and the mounting surface.
**Adds the following to the types of connections permitted for flexible cords and cables: portable and mobile signs and connection of moving parts. The proposal also clarifies that flexible cords and cables may be used for temporary wiring as permitted in § 1910.305(a)(2)
No substantive change. (Clarifies that flexible cords and cables may not be installed inside raceways.)
**Permits additional cord types to be used in show windows and show cases.
**Adds new types of cords to the list of those that must be marked with their type designation.
**Changed the minimum size of hard service and junior hard service cords that may be spliced from No. 12 to 14.
**Permits the minimum size of the insulated ground- check conductor of Type G-GC cables to be No. 10 rather than No. 8.
**Adds a requirement for shields to be grounded.
**Adds minimum bending radii requirements for portable cables.
**Also permits fixture wire to be used in fire alarm circuits.
No substantive change. (Clarifies that metal-shell paper-lined lampholders may not be used for handlamps.)
**Adds a requirement that the grounded circuit conductor, where present, be connected to the screw shell.
**Adds requirements to ensure that attachment plugs and connectors have no exposed live parts.
**Clarifies that nongrounding-type receptacles may not be used with grounding-type attachment plugs.
**Adds requirements for receptacles outdoors to be installed in weatherproof enclosures appropriate for the use of the receptacle and for the location.
**Adds a requirement to group and identify disconnecting means for appliances supplied by more than one source.
**Adds requirements for marking frequency and required external overload protection for appliances.
**Clarifies that markings must be visible or easily accessible after installation.
Removed. All disconnecting means must be capable of being locked in the open position by § § 1910.302(c) and 1910.303(f)(4)
Removed. Covered by § 1910.303(g)(2), (h)(2), and (h)(5).
No substantive change. (Oil- insulated transformers installed indoors are presumed to present a hazard to employees, and lack of employee exposure to a hazard is an affirmative defense.)
**Adds a requirement to ensure adequate rating of disconnecting means. The proposal also clarifies when the supply circuit disconnecting means may be used as the disconnecting means for induction and dielectric heating equipment.
**Adds requirements limiting primary and secondary voltage on isolating transformers supplying receptacles for ungrounded cord- and plug-connected equipment. Also, adds requirement for overcurrent protection for circuits supplied by these transformers.
**Allows the disconnecting means for a center pivot irrigation machine to be located not more than 15.2 m (50 ft) from the machine if the disconnecting means is visible from the machine. (Individual requirements are placed in separate paragraphs.)
**Clarifies that hydro-massage bathtubs are covered by this paragraph.
**Extends the boundary within which receptacles require GFCI protection from 4.57 m (15 ft) to 6.08 m (20 ft) for new installations.
**Adds requirements for the installation of at least one receptacle near permanently installed pools at dwelling units.
**Clarifies that ceiling suspended (paddle) fans are covered by this requirement.
**Adds a requirement to guard lighting fixtures facing upward.
**Adds requirements for carnivals, circuses, fairs, and similar events.
**Adds the Zone classification system for Class I locations. (See detailed discussion later in this section of the preamble.)
**Adds documentation requirements for hazardous locations classified using either the division or zone classification system.
**Also permits fixtures approved for Class II, Division 2 locations to omit the group marking.
**Adds a requirement that electric equipment suitable for an ambient temperature exceeding 40EC (104EF) be marked with the maximum ambient temperature.
The last sentence of the note is removed to make it clear that the OSHA standard does not incorporate the National Electrical Code by reference. The NEC continues to be a guideline that employers may follow in determining the type and design of equipment and installations that will meet the OSHA standard.
**The proposal lists the specific protective techniques for electrical installations in hazardous locations classified under the division classification system.
**Adds the zone classification system as an alternative method of installing electric equipment in hazardous locations. This paragraph sets the protective techniques and other requirements necessary for safe installation of electric equipment in hazardous locations classified under the zone classification system. (See detailed discussion later in this section of the preamble.)
**Adds the following wiring methods to those acceptable for installations operating at more than 600 V: electrical metallic tubing, rigid nonmetallic conduit, busways, and cable bus. The proposal also removes the specific requirement to support cables having a bare lead sheath or a braided outer covering in a manner to prevent damage to the braid or sheath. This hazard is covered by § 1910.303(b)(1) and (b)(8)(i) and new § 1910.308(a)(4)
**Adds requirements to ensure that high- voltage cables can adequately handle the voltage stresses placed upon them and to ensure that any coverings are flame retardant.
**Adds requirements for the protection of high-voltage cables against moisture and physical damage where the cable conductors emerge from a metal sheath.
**Adds requirements for fuses to protect each ungrounded conductor, for adequate ratings of fuses installed in parallel, and for the protection of employees from power fuses of the vented type.
**Clarifies that distribution cutouts are not suitable for installation in buildings or transformer vaults.
**Adds requirements for fused cutouts to either be capable of interrupting load current or be supplemented by a means of interrupting load current. In addition, a warning sign would be required for fused cutouts that cannot interrupt load current.
**Adds a requirement for guarding nonshielded cables and energized parts of oil-filled cutouts.
**Adds requirements to ensure that load interrupting switches will be protected against interrupting fault current and to provide for warning signs for backfed switches.
**Clarifies that multiconductor portable cable may supply mobile equipment.
**Limits the conditions under which switch or contactor enclosures may be used as junction boxes or raceways.
**Clarifies that emergency illumination includes all required means of egress lighting, illuminated exit signs, and all other lights necessary to provide required illumination.
**Adds requirements to provide signs indicating the presence and location of on-site emergency power sources under certain conditions.
**Clarifies the definitions of Class 1, 2, and 3 remote control, signaling, and power-limited circuits based on equipment listing.
**Adds requirements for the separation of cables and conductors of Class 2 and Class 3 circuits from cables and conductors of other types of circuits.
**Adds a requirement for power-limited fire alarm circuit power sources to be listed and marked as such.
**Clarifies the requirements for installing power- limited fire- protective signaling circuits with other types of circuits. (Individual requirements are placed in separate paragraphs.)
**Clarifies the requirement for listed primary protectors to make it clear that circuits confined within a block do not need protectors.
**Adds requirements to separate conductors of solar photovoltaic systems from conductors of other systems and to provide a disconnecting means for solar photovoltaic systems.
**Adds an exception to the provisions on the location of overcurrent protective devices for integrated electrical systems.
Note to table:
**These new and revised provisions are included in the 2000 edition of NFPA 70E standard. The NFPA 70E Committee believes that these provisions, which were taken from the 1999 NEC, are essential to employee safety. OSHA agrees with the consensus of NFPA's expert opinion that these requirements are reasonably necessary to protect employees and has included them in the proposed rule. On occasion, OSHA has rewritten the provision to lend greater clarity to its requirements. However, these editorial changes to the language of NFPA 70E do not represent substantive differences. NFPA's handling of these provisions and the rationale underpinning them is a matter of public record for the NEC and NFPA 70E. OSHA agrees with the rationale in this record as it pertains to the new and revised provisions the Agency is proposing. OSHA has placed the public record on all editions of the NEC and NFPA 70E after 1978 into the public docket for this rulemaking.
D. Branch Circuits-Ground Fault Circuit Interrupters for Employees
Introduction. Each year many employees suffer electric shocks while using portable electric tools and equipment. The nature of the injuries ranges from minor burns to electrocution. Electric shocks produced by alternating currents of power line frequency passing through the body of an average adult from hand to foot for 1 second can cause various effects, starting from a condition of being barely perceptible at 1 milliampere to loss of voluntary muscular control from 9 to 25 milliamperes. The passage of still higher currents can produce ventricular fibrillation of the heart from 75 milliamperes to 4 amperes and, finally, immediate cardiac arrest at over 4 amperes. These injuries occur when employees contact electrically energized parts. Typically, the frame of a tool becomes accidentally energized because of an electrical fault that provides a conductive path to the tool casing. When the employee contacts the tool casing, the fault current flows through the employee to ground. The amount of current that flows through an employee depends, primarily, upon the resistance of the fault within the tool, the resistance of the employee, and the resistance of the path from the employee back to the electric power supply. Moisture in the atmosphere can contribute to the electrical fault by intensifying both the conductive path within the tool and the external path back to the electric power supply. Dry skin can have a resistance range of about 500 to 500,000 ohms and wet skin can have a resistance range of about 200 to 20,000, depending on several factors, such as the weight of the employee. Thus, more current will flow if the employee is perspiring or becomes wet because of environmental conditions.
One method of protection against injuries from electric shock is the ground-fault circuit interrupter (GFCI). This device continually monitors the current flow to and from electric equipment. If the current going out of the equipment differs by 0.005 amperes from the current returning, then the GFCI will deenergize the equipment within as little as 25 milliseconds, quickly enough to prevent electrocution.
GFCI requirements. Proposed § 1910.304(b)(4) would set new requirements for ground-fault circuit interrupter protection of receptacles and cord connectors used in general industry. As noted earlier, this provision would only apply to installations made after the effective date of the final rule. Paragraph (b)(4)(i) would require ground-fault circuit protection for 125-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms and on rooftops. Cord- and plug-connected equipment in these locations can get wet and expose employees to severe ground-fault hazards. The NFPA 70E Committee believes, and OSHA agrees, that using 125-volt, 15- and 20-ampere cord-and plug-connected equipment in these locations exposes employees to a risk of electrocution great enough to warrant the protection afforded by ground-fault circuit interrupters.
Paragraph (b)(4)(ii) would require ground-fault circuit interrupter protection for receptacles on temporary wiring installations that are used during maintenance, remodeling, or repair of buildings, structures, or equipment, or during similar activities. However, receptacles on a 2-wire, single-phase portable or vehicle-mounted generator rated not more than 5 kW would be permitted without ground-fault circuit-interrupter protection if the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces.
OSHA currently requires GFCI protection for 120-volt, 15- and 20-ampere temporary receptacle outlets used on construction sites (§ 1926.404(b)(1)). In the 26 years that this requirement has been in effect, the Agency estimates that between 500 and 750 lives have been saved because of it.(15) Temporary wiring associated with construction-like activities exposes employees to the same ground-fault hazards as those associated with temporary receptacle outlets on construction sites. In § 1910.304(b)(4)(ii), OSHA is proposing to extend this requirement to temporary receptacles used in construction-like activity performed in general industry. The proposal would extend protection to receptacles of higher voltage and current ratings. This will better protect employees from ground-fault hazards than the construction rule because it covers other equipment that is just as subject to damage as 120-volt, 15- and 20-ampere equipment and that is more prevalent today than when the construction rule was promulgated.
The Agency is not proposing to permit the NFPA 70E assured grounding program as an alternative to GFCIs in general industry and maritime employment. NFPA 70E's assured grounding program differs in several important respects from the assured grounding program in OSHA's construction standards. For example, NFPA 70E permits the assured grounding program as an alternative to GFCIs only (1) for industrial establishments with conditions of maintenance and supervision that ensure that only qualified personnel are involved and (2) for receptacle outlets rated other than 125 volts and 15, 20, or 30 amperes. The OSHA construction rule recognizes the assured grounding program as an alternative to GFCIs without restriction. Additionally, under the assured grounding program, NFPA 70E requires electric equipment to be tested only when there is evidence of damage. This is in contrast to the assured grounding program required by OSHA's construction standard, which requires electric equipment to be tested after any incident that can reasonably be suspected to have caused damage. OSHA believes that these differences would be confusing for employers who are subject to both standards and would offer less protection for employees.
OSHA also considered including the assured grounding program requirements from the construction standard as an alternative to GFCIs in this proposed rule. However, the Agency believes that GFCIs alone, without the assured grounding program as an alternative will provide better protection for employees. The construction standard's assured grounding program demands constant vigilance on the part of employees to provide them with the same level of protection as GFCIs. Under that program, employers must test cord- and plug-connected equipment generally at 3-month intervals, and employees must inspect them daily. In contrast, GFCIs constantly monitor the circuit for ground faults and open the circuit when ground-fault current becomes excessive without the need for either the employer or the employee to take. Considering that three fourths of all electrical accidents are caused by poor work practices (55 FR 31986), OSHA believes that GFCIs are a much more reliable method of protecting employees.
For these reasons, OSHA believes that this proposal would afford better protection for employees than NFPA 70E. However, OSHA requests comments on whether the assured grounding program required by the electrical standards for construction in § 1926.404(b)(1)(iii) provides equal or better protection for employees than GFCIs, and whether it should be added as an alternative to GFCIs in the general industry electrical installation standard.
E. Carnivals, Circuses, Fairs, and Similar Events
The proposed standard has new requirements for carnivals, circuses, exhibitions, fairs, traveling attractions, and similar events. These requirements, which are based on corresponding requirements in NFPA 70E, would cover the installation of portable wiring and equipment for these temporary attractions. From 1991 to 2002, OSHA received reports of 46 serious accidents (16) associated with carnivals, circuses, exhibitions, fairs, and similar events. Eleven of these accidents, resulting in 10 fatalities and 5 injuries, involved electric shock. Eight of those 11 cases (8 fatalities and 1 injury) involved electric wiring and equipment covered by the installation requirements in Subpart S. OSHA believes that the new electrical requirements for these events will prevent similar accidents in the future.
In paragraph (k) of § 1910.306, mechanical protection of electric equipment and wiring methods would be required in and around rides, concessions, or other units subject to physical damage. Inside tents and concession stands, the electrical wiring for temporary lighting would need to be secured and protected from physical damage. These new provisions would provide more electrical safety for employees working in and around this equipment.
The disconnecting means would need to be readily accessible to the operator; that is, the fused disconnect switch or circuit breaker would have to be located within sight and within 6 feet of the operator for concession stands and rides. This provision would provide protection by enabling the operator to stop the equipment in an emergency. The disconnecting means would also have to be lockable if it is exposed to unqualified persons, to prevent such persons from operating it.
F. Zone Classification
Introduction. Section 1910.307 contains OSHA's electrical safety requirements for locations that can be hazardous because of the presence of flammable or combustible substances. Hazardous locations are currently classified according to the properties of flammable vapors, liquids or gases, or combustible dusts or fibers that may be present. These locations are designated in the NEC and § 1910.307 as one of six types: Class I, Division 1; Class I, Division 2; Class II, Division 1; Class II, Division 2; Class III, Division 1; and Class III, Division 2. This system is called the "division classification system," or the "division system." The NEC first addressed this system in 1920. The OSHA website has a short but informative paper on this topic, which is available at http://www.osha.gov/doc/outreachtraining/htmlfiles/hazloc.html.
The latest version of NFPA 70E incorporates an alternative system (in addition to the division classification system) for installing electric equipment in Class I locations. (Class II locations continue under the division system.) This system is called the "zone classification system," or the "zone system." The zone system designates three classifications: Class I, Zone 0; Class I, Zone 1; and Class I, Zone 2. The zone system is based on various European standards that were developed by the International Electrotechnical Commission (IEC).(17) A modified version of this system was first adopted into the NEC in the 1996 edition. Although the zone and division classification systems differ in concept, individual equipment can be approved for use under both systems when the equipment incorporates protective techniques for both systems (as determined by the nationally recognized testing laboratory that lists or labels the equipment).
The zone system is an alternative method to the division system; employers may use either system for installations of electric equipment in Class I hazardous locations. OSHA proposes to permit the use of the zone system under § 1910.307 and any other OSHA standard that references § 1910.307.
As noted earlier, OSHA is proposing in § 1910.307(b) to require employers to document the designation of hazardous locations within their facilities. The documentation must denote the boundaries of each division or zone so that employees who install, inspect, maintain, or operate equipment in these areas will be able to determine whether the equipment is safe for the location. As noted earlier, OSHA is proposing to require documentation for the division system only for new installations that use that system. It would apply to all installations made under the zone system.
Proposed changes to OSHA's existing requirements for the division classification system. The term "hazardous concentrations" is currently used in various definitions of specific hazardous locations in § 1910.399. For example, § 1910.399 defines "Class I, Division 1," in part, as follows:
A Class I, Division 1 location is a location: (a) in which hazardous concentrations of flammable gases or vapors may exist under normal operating conditions * * *
The proposal would change the term "hazardous concentrations" to "ignitable concentrations" in each of the definitions. This change would reflect changes already incorporated into the 1999 NEC and the 2000 edition of NFPA 70E to make the definition more specific about the hazard being addressed. The changes will make these definitions clearer in addition to making the OSHA standard consistent with the latest editions of NEC and NFPA 70E.
OSHA is also proposing to add a new paragraph (f) to § 1910.307 that sets acceptable protection techniques under the division system. These requirements address design features that must be used to protect employees who are using equipment in a hazardous location classified under the division system. Neither the current Subpart S nor NFPA 70E explicitly require specific protection techniques that may be used in the division classification system; however, the NEC does require specific protection techniques for installations made under the division classification system in various requirements spread throughout the Articles covering hazardous locations. OSHA has listed these techniques in one paragraph in the proposal to make the standard easier to use and to provide parallel requirements for both the division classification system and the zone classification system. Protective techniques other than those listed in paragraph (f) are acceptable if the equipment is: (1) Intrinsically safe as specified in § 1910.307(c)(1); approved for the specific hazardous location as specified in § 1910.307(c)(2); or (3) of a type and design that the employer demonstrates is safe for the specific hazardous location as specified in § 1910.307(c)(3). New paragraph (f) is intended to clarify the existing OSHA requirements for hazardous locations by explicitly listing the types of protective techniques used under the division classification system. (The protection techniques are required implicitly under the existing standard through the requirements for approval and listing or labeling by a nationally recognized testing laboratory and through the reference to the National Electrical Code in the note following § 1910.307(b)(3).)
Brief background and description of the zone system. The zone system stemmed from the independent efforts of countries in Europe and elsewhere to develop an area classification system to address safety in locations containing hazardous substances. The IEC formalized these efforts into the zone system, which is now used to classify the majority of the world's hazardous location systems.(18)
Article 505 of the 1996 NEC included requirements for the U.S. version of the zone system for the first time. The current version of NFPA 70E (NFPA 70E-2000) includes requirements for the zone system based on the 1999 version of the NEC. OSHA is proposing to adopt zone system rules that are based on these NFPA 70E provisions. This will permit electric equipment approved for use in hazardous locations to be used in U.S. workplaces, under either the division or zone system.
Major differences between the division classification system and the zone classification system. The zone system can best be described by comparing it with the division system. Both systems characterize locations by the likelihood and circumstances under which flammable gases or vapors exist. The systems both define the types of gases or vapors that may exist and categorize them under a number of groups. Each system specifies an allowable range of operating temperature, and corresponding requirements, for electric equipment used in a particular division or zone.
In contrast to the division system, however, the zone system is only used to classify areas that are hazardous because of the presence of flammable gases or vapors (Class I locations). The division system must be used to classify areas that may contain combustible dusts or easily ignitable fibers or flyings (Class II and III locations, respectively).
The zone system defines three types of Class I locations (Zones 0, 1, and 2) rather than two locations under the division system (Divisions 1 and 2). Zones 0 and 1 equate to Division 1, whereas Zone 2 equates to Division 2. In a Class I, Division 1 location, flammable gases or vapors are or may be present in the air in ignitable concentrations. In a Class I, Zone 1 location, ignitable concentrations of flammable gases or vapors are not always present, but such concentrations may exist periodically even under normal conditions. By contrast, in a Class I, Zone 0 location, such gases or vapors are present either continuously or for long periods of time. (See Table 2.) Thus, a Class I, Zone 0 location is, in essence, a worst-case Class I, Division 1 location.
Each system classifies flammable gases and vapors into a number of groups. The division system has four such groups, designated A, B, C, and D, with group A containing the most volatile substances, and groups B, C, and D containing gases or vapors that are progressively less volatile. The zone system has three such groups, designated IIA, IIB, and IIC, with group IIC containing the most volatile gases, and groups IIA and IIB containing gases or vapors that are progressively less volatile. Substances classified under Groups A and B in the division system generally fall under Group IIC of the zone system. However, some differences exist between the groups in the two systems. Thus, regardless of the classification system being used, equipment intended for use in a Class I hazardous location must indicate the groups for which it is approved, as required by proposed § 1910.307(c)(2)(ii) and (g)(5)(ii). Table 2 summarizes the similarities and differences between the two systems.
The other major differences concern the allowable protection schemes and the maximum allowable surface temperature of equipment under each system. The protection schemes acceptable for each division and zone are listed in Table 3, and the remainder of this paragraph discusses the differences in maximum allowable temperature. According to the NEC, equipment is acceptable for a hazardous location only if its surface temperatures will not approach the ignition temperature, or more specifically the autoignition temperature, of the particular gases and vapors that might be present in that location. There are 14 temperature limits, and corresponding identification codes, under the division system. Each limit specifies the maximum surface temperature for equipment labeled with the matching code. There are six such temperature limits and corresponding identification codes under the zone system. The six zone system limits correspond directly to 6 of the 14 division system temperature limits. However, as shown in Table 2, the remaining eight division temperature limits have values intermediate to the six zone system temperature limits. For example, the division system has 4 intermediate temperature limits, 215°C, 230°C, 260°C, and 280°C (T2D, T2C, T2B, and T2A, respectively), between the zone system's temperature limits of 200°C (T3) and 300°C (T2). Equipment approved for one of these intermediate values may be used under the zone system only for the higher (in temperature) of the two closest zone system values. For example, equipment marked T2A under the division system, which has a maximum surface temperature of 280°C, could only be used in locations where the ignition temperature of the substance is greater than or equal to the T2 value, which is 300°C. In essence, T2A equipment becomes derated to T2 equipment when it is installed using the zone classification system. It could not be used in zone-classified locations where the ignition temperature of the substance is less than or equal to the T3 value, which is 200°C, because the equipment could become hot enough to cause ignition.
More details on the differences in gas groups. In the 1999 NEC, the definitions for each of the division system gas and vapor groups, except Group A,(19) were changed to make them comparable to the definitions of the zone system groups. A gas or vapor is classified in the division system's Group B, C, or D or the zone systems Group IIC, IIB, or IIA based on the gas's or vapor's maximum experimental safe gap (MESG) (20) or its minimum igniting current ratio (MIC ratio).(21) These values are established under standard experimental conditions for each gas and vapor.
The 1999 NEC indicates two factors that may affect MESG and MIC values: (1) Lower ambient temperatures (lower than minus 25°C or minus 13°F), and (2) oxygen enriched atmospheres. The 1999 NEC Handbook states that the latter factor can drastically change the explosion characteristics of materials. Such an atmosphere lowers the minimum ignition energy, increases the explosion pressure, and can reduce the maximum experimental safe gap. These factors would make it unsafe to use otherwise approved "intrinsically safe" and "explosion-proof" equipment, unless the equipment has been tested for the specific conditions involved. Employers must ensure that the equipment approval is valid for the actual conditions present where the equipment is installed. This is required generally for all electric equipment. However, it is essential in hazardous locations because of the dire consequences that may result.
Rationale for adopting the zone system requirements. As stated earlier, the zone system has been accepted in many countries. Such international acceptance has meant that U.S. manufacturers of electric equipment suitable for installation in hazardous locations have had to ensure that their equipment met the zone system requirements if they wished to sell such equipment in zone-system countries in addition to meeting the U.S. division system requirements. Also, U.S. employers that had hazardous locations in their workplaces have sought to use equipment approved for use only in zone-classified locations in this country. This, in turn, led NFPA to incorporate the zone system in the NEC starting in the 1996 edition.
OSHA has determined that employees can be protected from the hazards of explosion in Class I hazardous locations by the installation of electric equipment following the latest NEC requirements for the zone classification system (Article 505 of the 2002 NEC). Therefore, the Agency is incorporating the zone system in this proposed revision of the electrical installation requirements in Subpart S. Under the proposed standard, employers would be able to comply with either the zone classification system or the division system for Class 1 hazardous locations.
New § 1910.307(g) and related definitions. OSHA is proposing to add a new paragraph (g) to § 1910.307 to cover the zone classification system. This new paragraph addresses the following topics: scope; location and general requirements; protection techniques; special precaution; and listing and marking. A brief description of the contents of each paragraph follows.
Paragraph (g)(1) permits employers to use the zone classification system as an alternative to the division classification system. This paragraph also explains that the requirements in § 1910.307 that are specific to installations built under the division classification do not apply to installations built under the zone classification system. Thus, paragraph (c), electrical installations; paragraph (d), conduits; paragraph (e), equipment in Division 2 locations; and paragraph (f), protection techniques do not apply to installations built under the zone system. Paragraph (g) contains counterparts to each of these requirements.
Paragraphs (g)(2)(i) and (ii) describe how hazardous locations are classified under the zone system. The employer must consider each individual room, section, or area separately and must designate locations according to the specific properties of the flammable gases, liquids, or vapors that might be present. The same requirements apply to the division system. (See § 1910.307(a).)
Paragraphs (g)(2)(iii) and (g)(2)(iv) require that conduit threads be of certain types and that connections be made wrench tight. These provisions ensure that there is no arcing across conduit connections in the event that they have to carry fault current. Paragraph (d) contains similar requirements for division system installations.
Paragraph (g)(3) presents the protection techniques that are acceptable in zone-classified hazardous locations. Electric equipment in these locations must incorporate at least one of these protection techniques, and the equipment must be approved for the specific hazardous location. The protection techniques listed in the proposal have been taken directly from NFPA 70E-2000.
Paragraph (g)(4) sets special precautions that must be taken with respect to hazardous locations classified under the zone system. First, the classification of areas and the selection of equipment and wiring must be under the supervision of a qualified professional engineer. This provision is contained in NFPA 70E-2000 and in the 1999 NEC. Because the zone system has been permitted in the U.S. only since 1997,(22) employers and installers in this country have relatively little experience with installations made using the zone classification system. The experts that developed NFPA 70E and the NEC have determined that, for the zone system, it is essential for competent persons to classify the hazardous locations and select equipment for those locations. OSHA agrees with these experts. Paragraph (g)(4) also indicates when it is safe to have locations classified using the division system on the same premises as locations classified under the zone system and vice versa. These provisions are also taken from NFPA 70E-2000.
Paragraph (g)(5) contains requirements for marking equipment that is approved for hazardous locations classified under the zone system. These provisions are comparable to the corresponding marking requirements under the division system, but reflect the need to provide information necessary for safely installing equipment in a zone-classified location.
Equivalence of systems and permitted protection techniques. Table 2 shows the general equivalence between the two classification systems. It should be noted, however, that a given area classified under one system is not permitted to overlap an area classified under the other system. For example, although Division 2 and Zone 2 are basically equivalent classifications, under the proposed standard a Zone 2 location is permitted to touch a Division 2 location, but the two locations are not permitted to overlap. This ensures that equipment installed and maintenance performed in these locations are appropriate for the conditions in each location.(23)
Table 2.--Equivalence of Hazardous (Classified) Location Systems, Class I Locations Only (1) (2)
Category Division system Zone system
Gas Groups (see Table 3 since systems are not fully equivalent)
Temperature Codes. Division 1
T1 (<450°C)
T2A, T2B, T2C, T2D (<280, <260, <230, <215°C)
T3A, T3B, T3C (<180, <165, <160°C).
T4A (<120°C)
T4 T5 (<100°C)
T6 (<85°C) Zone 0, Zone 1.
Zone 2.
IIC (not fully equivalent to Groups A and B).
IIB (not fully equivalent to Group C).
IIA (not fully equivalent to Group D).
T2 (effectively)(3)
T6 (<85°C).
Notes to Table 2:
1 Use of the equivalence shown in the table above must be done only as permitted by § 1910.307.
2 The zone classification system described in this preamble does not cover Class II or Class III locations.
3 See the discussion of maximum allowable surface temperatures earlier in the preamble.
Table 3 describes which protection techniques may be used in which classified locations.
Table 3.--Permitted Protection Techniques (Design Criteria) in Class I Locations
Division 1:
--explosion-proof
--purged and pressurized (Type X or Y)
--intrinsically safe
--purged and pressurized (Type Z)
--nonincendive
--oil immersion
--hermetically sealed
--any Class I, Division 1 method
--any Class I, Zone 0, Zone 1, or Zone 2 method Zone 0:
--intrinsically safe "ia"
--Class I, Division 1 intrinsically safe
--flameproof "d"
--purged and pressurized
--intrinsically safe "ib"
--oil immersion "o"
--increased safety "e"
--encapsulation "m"
--powder filling "q"
--any Class I, Zone 0 method
--non-sparking "nA"
--protected sparking "nC"
--restricted breathing "nR"
--any Class I, Division 1 or 2 method
--any Class I, Zone 0 or 1 method
Listing and labeling by NRTLs. Paragraph (a) of proposed § 1910.303 would continue the existing requirement that all electric equipment be approved. While OSHA believes that approval is necessary for all electric equipment, the need for third-party approval of electric equipment in hazardous locations is crucial in most circumstances. The techniques for ensuring safety in hazardous locations require careful manufacturing and testing of products because tolerances are tight and the margin for error is slim. Thus, OSHA's general industry electrical installation standard has always called for equipment approval, which generally requires listing or labeling by a nationally recognized testing laboratory (NRTL) of equipment installed in hazardous locations.(24) Under 29 CFR 1910.7, OSHA recognizes testing organizations that are capable of performing third-party testing for safety and designates them as NRTLs. Employers may use products listed by NRTLs to meet OSHA standards that require testing and certification. NRTLs test and certify equipment to demonstrate conformance to appropriate test standards. Many of these test standards cover equipment used in hazardous locations.
OSHA's existing requirements for hazardous locations in Subpart S only address locations classified under the division system, and NRTLs perform testing based on that system. However, test standards currently used by NRTLs to test equipment in hazardous locations classified by division are not automatically appropriate for testing such equipment for use under the zone system. These current test standards are based on protective techniques used for equipment designed for use under the division system and do not contain criteria for protective techniques used in the zone system. Electric equipment that has been approved by a NRTL for use in division-classified hazardous locations may be capable of igniting flammable gases or vapors when used inappropriately in zone-classified locations. Such hazardous equipment can cause a catastrophic explosion and the deaths of and injuries to many employees. In recognizing laboratories under § 1910.7 to test products designed for installation in zone-classified locations, OSHA will ensure that the proper test standards are used and look closely at the capability of the laboratory to perform testing under those standards.
Effects and changes to other Part 1910 standards (§ § 1910.103, 1910.106, 1910.107, 1910.110, 1910.178, and 1910.253). A number of other OSHA standards under 29 CFR Part 1910 contain references to or requirements related to § 1910.307. Some of these standards refer only to hazardous locations classified under the division system. The standards particularly affected are as follows:
§ 1910.103(b)(3)(ii)(e) and (b)(3)(iii)(e), (c)(1)(ix)(a), and (c)(1)(ix)(b);
§ 1910.106(d)(4)(iii), (e)(7)(i)(b), (e)(7)(i)(c), (e)(7)(i)(d), (g)(1)(i)(g), (g)(4)(iii)(a), (h)(7)(iii)(b), and (h)(7)(iii)(c);
§ 1910.107(c)(6), (c)(8), (j)(4)(iv);
§ 1910.110(b)(17)(v);
§ 1910.178(c)(2)(iv) and (q)(2); and
§ 1910.253(f)(4)(iv)(B) and (f)(6)(v).
OSHA is not proposing to modify any of these standards in this rulemaking. Several of these requirements call for designating particular locations as Class I, Division 1 or Division 2 locations, and OSHA does not believe that revising them would be a straightforward or transparent process. For example, § 1910.103(c)(1)(ix)(a) requires electric wiring and equipment "located within 3 feet of a point where connections are regularly made and disconnected, shall be in accordance with subpart S of this part, for Class I, Group B, Division 1 locations." Under the zone system this location would likely be partly a Zone 0 location and partly a Zone 1 location. Thus, this requirement cannot be revised by a straightforward substitution of "Zone" for "Division." Similar problems exist in revising the other requirements. OSHA requests comments on whether these provisions should be modified to recognize installations made using the zone system and, if so, on what specific changes should be made to accomplish this.
G. Definitions
The definitions for Subpart S are located in § 1910.399. The proposed changes in these definitions reflect the provisions of the 1999 National Electrical Code and NFPA 70E-2000.
OSHA is proposing to remove several definitions from the standard. "Identified," as used in reference to a conductor or its terminal, would be removed because the proposal would discontinue the current standard's use of the word "identified" in this manner. The proposal does define "identified" to refer to equipment suitable for a specific purpose, function, use, environment, or application. "Special permission," "permanently installed swimming pools, wading and therapeutic pools," and "storable swimming and wading pools" would be removed because these terms are not used in Subpart S. Lastly, the definitions of "electric sign" and "may" would be removed. The existing Subpart S definitions of these terms are not substantially different from the commonly accepted dictionary definitions. Thus, their removal would not change the meaning of the standard.
OSHA is proposing to add fifteen definitions to § 1910.399. These definitions, all but one of which are based on NFPA 70E-2000, will help clarify the requirements in Subpart S. Other modifications made to the definitions are grammatical, and no substantive change is being made in the meaning of the terms. Table 4 summarizes the changes to the definitions.
Table 4.--Summary of Changes to the Definitions
Old definition New definition Rationale
Electric sign
Permanently installed swimming pools, wading and therapeutic pools.
Special permission
Storable swimming or wading pool.
Utilization system Barrier
Class I, Zone 0
Deenergized
Energized
Live parts
Unqualified Person
[Removed] OSHA would add this definition to § 1910.399 from NFPA 70E- 2000.
OSHA would add this definition to § 1910.399 from NFPA 70E-2000.
OSHA would add this definition to § 1910.399 from NFPA 70E- 2000 to support the new section on Zone Classification in § 1910.307.
OSHA would add this definition to § 1910.399 from NFPA 70E- 2000.
No substantive change. The definition adds nothing to the dictionary definition of this term.
This term is used in a different manner in the proposed revision. The new use and definition are taken from NFPA 70E- 2000.
No substantive change. adds nothing to the dictionary definition of this term.
OSHA would use this term in the standard in place of "major replacement, modification, repair, or rehabilitation," which is used in the existing standard to delineate when an electrical installation must meet new requirements in the standard. See the explanation of the definition and related changes under the summary and explanation of the grandfather clause earlier in this preamble.
This term is not used in Subpart S.
This definition would be removed. The existing definition appears to conflict with the scope of Subpart S. See the detailed explanation earlier in this section of the preamble.
A few terms warrant additional explanation: "identified," "labeled," and "listed." The existing standard requires certain electric equipment to be "approved for the purpose," and current § 1910.399 defines this term as follows:
Approved for a specific purpose, environment, or application described in a particular standard requirement.
Suitability of equipment or materials for a specific purpose, environment or application may be determined by a nationally recognized testing laboratory, inspection agency or other organization concerned with product evaluation as part of its listing and labeling program. (See "Labeled" or "Listed.")
In the proposal, OSHA is replacing the word "approved," when used in this sense, with "identified." The proposed definition of "identified," which is based on the definition of this term in NFPA 70E,(25) reads as follows:
Identified (as applied to equipment). Approved as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular requirement.
Note to the definition of "identified:" Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a nationally recognized testing laboratory (through listing and labeling), and inspection agency, or other organization recognized under the definition of "acceptable."
The proposed definition of "identified" as it applies to equipment is intended to be equivalent to the existing definition of "approved for the purpose." (26)
In the proposal, OSHA uses the terms "listed" and "labeled" to refer to electric equipment determined to be safe by a nationally recognized testing laboratory (NRTL). When equipment has been listed and labeled, this means that the equipment has been tested and found safe for use by a nationally recognized testing laboratory. The laboratories mark the equipment with a symbol identifying their trademark. The equipment is then considered by OSHA to be safe for its intended use. If the equipment is altered or used for other purposes, then the equipment is not acceptable under Subpart S. The laboratories typically require the equipment to be marked with such information as: the standards under which the equipment has been tested; the current rating in amperes; and the frequency. OSHA evaluates and recognizes "nationally recognized testing laboratories" under § 1910.7 to test equipment for safety and label or list it. It should be noted that the proposed rule would continue the existing § 1910.399 definitions of "labeled" and "listed" without substantive change.
H. Appendices
Appendices B and C of current Subpart S contain no material; they are reserved for future use. OSHA is proposing to remove these "empty" appendices because neither the Agency nor NFPA 70E currently have material to include there. NFPA 70E does have substantial appendix material relating to safety-related work practices, but not installations, in Part II of that standard. OSHA will consider whether to include or use the NFPA 70E appendices when the Agency revises its electrical safety-related work practices standard (§ § 1910.331 through 1910.335) in the future.
Existing Appendix A contains a list of references. OSHA is proposing to revise and update the references in this appendix to reflect the most recent editions of various national consensus standards. These nonmandatory references can assist employers who desire additional information that will help them to comply with the performance standard in Subpart S. For example, if an employer complies with the detailed specifications of the 1999 National Electrical Code, the employer will be considered as being in compliance with the more performance-oriented requirements found in Subpart S. In addition, OSHA is proposing to remove various reference standards from the appendix because the documents are no longer in print and because the information can be found in other listed sources. The references that would be removed are:
ANSI B9.1-71 Safety Code for Mechanical Refrigeration;
ANSI B30.7-77 Base Mounted Drum Hoists;
ANSI B30.15-73 Safety Code for Mobile Hydraulic Cranes;
ANSI C33.27-74 Safety Standard for Outlet Boxes Fittings for Use in Hazardous Locations, Class I, Groups A, B, C, and D, and Class II, Groups E, F, and G;
ASTM D2155-66 Test Method for Autoignition Temperature of Liquid Petroleum Products;
IEEE 463-77 Standard for Electrical Safety Practices in Electrolytic Cell Line Working Zones;
NFPA 56A-73 Standard for the Use of Inhalation Anesthetics (Flammable Nonflammable);
NFPA 56F-74 Standard for Nonflammable Medical Gas Systems;
NFPA 70C-74 Hazardous Locations Classification;
NFPA 71-77 Standard for the Installation, Maintenance, and Use of Central Station Signaling Systems;
NFPA 72A-75 Standard for the Installation, Maintenance, and Use of Local Protective Signaling Systems for Watchman, Fire Alarm, and Supervisory Service;
NFPA 72B-75 Standard for the Installation, Maintenance, and Use of Auxiliary Protective Signaling Systems for Fire Alarms Service;
NFPA 72C-75 Standards for Installation, Maintenance, and Use of Remote Station Protective Signaling Systems;
NFPA 72D-75 Standard for the Installation, Maintenance and Use of Proprietary Protective Signaling Systems for Watchman, Fire Alarm, and Supervisory Service;
NFPA 72E-74 Standard for Automatic Fire Detectors;
NFPA 74-75 Standard for Installation, Maintenance, and Use of Household Fire Warning Equipment;
NFPA 76A-73 Standard for Essential Electrical Systems for Health Care Facilities;
NFPA 86A-73 Standard for Ovens and Furnaces; Design, Location and Equipment;
NFPA 88B-73 Standard for Repair Garages;
NFPA 325M-69 Fire-Hazard Properties of Flammable Liquids, Gases, and Volatile Solids; and
NFPA 493-75 Standard for Intrinsically Safe Apparatus for Use in Class I Hazardous Locations and Its Associated Apparatus.
OSHA is proposing to add five national consensus standards to the list. All of these documents refer to hazardous (classified) locations.
ANSI/UL 913-2002 Intrinsically Safe Apparatus and Associated Apparatus for Use in Class I, II, and III, Division 1, Hazardous (Classified) Locations;
ANSI/UL 2279-1997 Electrical Equipment for Use in Class I, Zone 0, 1 and 2 Hazardous (Classified) Locations;
ANSI/API RP 500-1998 (2002) Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I Division 1 and Division 2;
ANSI/API RP 505-1998 (2002) Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1 and Zone 2; and
NFPA 820-1999 Standard for Fire Protection in Wastewater Treatment and Collection Facilities.
I. Powered Platforms for Building Maintenance
Mandatory Appendix D to § 1910.66, powered platforms for building maintenance, applies to powered platforms installed between August 28, 1971, and July 23, 1990. Paragraphs (c)(22)(i) and (c)(22)(vii) in that appendix incorporate the 1971 National Electrical Code by reference. OSHA is proposing to reference Subpart S instead. The proposal, which would replace the highly specification-oriented NEC with the performance-oriented Subpart S, would make the standard more flexible for employers maintaining these platforms but would retain the protection currently afforded employees.(27) In addition, employers would no longer need to refer to the NEC to determine how to comply with OSHA's standard for powered platforms. The Agency requests comments on whether replacing the reference to the NEC with one to Subpart S is reasonable and appropriate.
A. Existing Versus Proposed Standard
The proposed rule would revise and update the provisions contained in Sections 1910.302-1910.308 and 1910.399 of the existing Subpart S electrical installation standard. The original version of Subpart S, adopted under section 6(a) of the OSH Act, incorporated the 1971 National Electrical Code (NEC) by reference. In 1981, OSHA replaced the incorporation by reference with updated provisions based on the 1979 National Fire Protection Association (NFPA) 70E committee recommendations. The 1981 version relied on the 1978 NEC. The proposed rulemaking will revise and update the OSHA electrical installation standard to be consistent with most of the NFPA 70E recommendations developed in 2000, which are based on the 1999 NEC, and to update requirements for new electrical installations.
OSHA has conducted a detailed comparison of the existing and proposed rules in order to determine which provisions are expected to increase compliance costs. Table 5 summarizes the changes associated with the provisions of the proposed rule and their implications for compliance costs. The OSHA comparative analysis indicates that the changes in the proposed rule fall into four categories: (1) Changes in hardware specifications that are consistent with NEC requirements; (2) changes in installation practices that are consistent with current, normal and customary installation practices routinely followed by licensed electricians; (3) clarifications of existing requirements that do not add additional obligations and/or allow greater flexibility for achieving compliance; and (4) requirements that may require significant changes in electrical system and equipment installation practices.
The first three categories of changes introduced by the proposed standard are not expected to result in any additional costs. Category 1 changes are not expected to increase costs because most equipment manufacturers routinely follow current NEC requirements regarding hardware specifications. Category 2 changes are not expected to result in any increase in compliance costs since most licensed electricians routinely follow NEC requirements for installing electrical systems and equipment. Category 3 changes do not add any new installation or work practice requirements, but simply restate or eliminate existing requirements.
Regarding Category 4, a number of changes indicated by the proposed rule correspond to revisions to the NEC made prior to 1999. Because these changes have been in the NEC since 1996,(28) they are believed to represent widespread current industry practice. Therefore, the changes are not expected to result in increased compliance costs. Moreover, construction requirements usually imposed by mortgage lenders and insurance carriers, as well as installation practices routinely followed by licensed electricians (given their formal training), are generally consistent with the NEC requirements. In sum, there is a subset of Category 4 changes that can be assumed to be equivalent to the Category 2 changes described above. Only those Category 4 changes that represent additions or revisions to the 1999 NEC are expected to potentially result in any increase in compliance costs.
As noted, many Category 4 changes are not expected to increase compliance costs. In order to avoid having employers incur the costs of retrofitting the existing electrical systems and equipment in their buildings and facilities, OSHA has identified (in § 1910.302(b)(4)) the substantive new provisions in the proposed standard, and then excluded (grandfathered) all existing electrical systems and equipment installations from having to comply with these new requirements. These provisions will only apply to new installations (that is, electrical systems and equipment installed for the first time, as well as installations that represent a major replacement, modification, repair, or rehabilitation of an existing electrical system) made after the effective date of the standard. Of the new provisions identified in § 1910.302(b)(4), there are 14 provisions (or sets of related provisions) in Category 4 that were added or last revised in the 1999 NEC. A number of these provisions represent changes in design and/or operating practices. OSHA believes that with the appropriate lead time (that is, sufficient delay in the effective date of the proposed standard), these provisions should not result in any incremental costs because these requirements can be reviewed and considered, and the electrical installation practices altered as necessary, prior to any work being performed.
In addition to the provisions identified in § 1910.302(b)(4), there are also new provisions identified in § 1910.302(b)(2) and (b)(3) of the proposed standard that apply to: (1) Electrical system and equipment installations (either first time or major replacement, modification, repair, or rehabilitation) made after March 15, 1972; and (2) electrical system and equipment installations (either first time or major replacement, modification, repair, or rehabilitation) made after April 16, 1981, respectively. Reviewing the provisions identified in § 1910.302(b)(2) and (b)(3) of the proposed rule, there are 12 new provisions (or sets of related provisions) in Category 4 that were added or last revised in the 1999 NEC. Table 5 lists the provisions with cost implications. Again, a number of these provisions represent changes in design or operating practice rather than new equipment requirements, and as discussed earlier, are not expected to result in any incremental costs as long as there is sufficient delay in the effective date of the proposed standard.
OSHA has examined other new provisions for possible cost impacts. First, § 1910.302(b)(1) of the existing and proposed standards identifies those provisions (that is, specific sections in the standards) that all new and existing electrical system and equipment installations must meet regardless of the installation date. For these provisions in the existing and proposed standards, there is no grandfathering of older, existing electrical system and equipment installations. However, OSHA has concluded that proposed § 1910.302(b)(1) imposes no new, substantive Category 4 requirements for existing electrical systems and equipment installations. Further, while § 1910.302(b)(1) does add new coverage from § 1910.307, only documentation of hazardous locations is a totally new requirement. The rest of the new provisions in § 1910.307 allow employers to continue using the division system or to implement an alternative zone system for classifying hazardous locations containing flammable gases or vapors. They should not result in any additional costs unless employers voluntarily choose to abandon their present division system in favor of the alternative zone system. Finally, there are new proposed provisions not contained in the existing OSHA electrical installation standard that were originally in the 1971 NEC and were enforced by OSHA between March 15, 1972, and April 16, 1981. The latest version of NFPA 70E reincorporated these provisions. OSHA believes that these provisions represent widespread current industry practices, because they have been part of every version of the NEC since 1971, including the 1999 and 2002 editions, and will not impose any additional cost.
B. Potentially Affected Establishments
The proposed electrical safety standard is based primarily upon the 2000 NFPA 70E recommendations, which in turn, are based on the 1999 NEC. Consequently, companies that are installing electrical systems and equipment in their facilities in locations where the 1999 (or 2002) NEC is currently being followed will not be further impacted by OSHA's proposed rulemaking with respect to new installations. Further, given that there are no new, substantive Category 4 provisions in the proposed standard that are mandatory for all existing electrical system and equipment installations (see above discussion), these provisions will not result in any economic impact for existing installations, until they are replaced, repaired, and/or renovated.
In order to estimate the number of employers potentially impacted by the proposed rulemaking, OSHA has identified the States and municipalities that currently mandate the 1999 (or 2002) National Electrical Code (NEC), that currently mandate using an earlier NEC, or that have no mandated statewide electrical code pertaining to new installations.(29) These states were identified using information contained in the Directory of Building Codes and Regulations, by City and State (National Conference of States on Building Codes and Standards, NCSBCS, 2002). In sum, 34 of the 50 States have already passed mandatory minimum building or fire codes specifying that new construction (including new electrical installations) must meet or exceed the requirements of the 1999 (or 2002) National Electrical Code (NEC).(30) Thus, OSHA assumes that employers in the covered industries in all locations in these 38 States (except for Baltimore, MD) will be unaffected by OSHA's proposed rulemaking with respect to new installations. These States (with the particular NEC indicated) are listed below:
Alaska (1999)
Arkansas (1999)
Connecticut (1999)
Delaware (1999)
Idaho (2002)
Indiana (1999)
Kentucky (2002)
Maine (1999)
Minnesota (1999)
Montana (1999)
New Hampshire (1999)
New Mexico (1999)
North Carolina (1999)
North Dakota (2002)
Oklahoma (1999)
Oregon (1999)
Rhode Island (2002)
South Carolina (1999)
South Dakota (2002)
Tennessee (1999)
Utah (1999)
Vermont (1999)
West Virginia (1999)
Wyoming (1999)
Moreover, 16 large cities in other States have also adopted the 1999 NEC. Therefore, employers in the covered industries in these municipalities are also expected to be unaffected by OSHA's proposed rulemaking with respect to new installations. These cities are listed below:
Forth Worth, Texas
Further, the State of Alabama has adopted a limited mandatory minimum code, which requires that a number of industries follow 1999 NEC. These industries include hotels, schools, and movie theaters. Therefore, in this analysis, these identified industries in Alabama have been included with the group of 38 States and 16 large cities (described above) that currently follow the 1999 NEC.
The remaining 12 States (or portions of these States) that would likely be affected by OSHA's proposed rulemaking can be separated into two subgroups: (1) States or municipal jurisdictions that have adopted the 1996 version of the NEC; and (2) States that have not adopted any statewide electrical code covering all non-government-owned buildings or facilities (that is, private sector installations). For group 1, it is likely that these jurisdictions will adopt a later version of the NEC at some point in the future. This will likely result in lower annual compliance costs than estimated below.
Five States and three cities fall into the first of the two subgroups described above. These include all locations in Louisiana and Virginia, as well as portions of Arizona, Iowa, and Nevada (that is, all locations in these three States excluding the four large cities in these States that have adopted the 1999 NEC, as indicated in the list above). The three large cities in the first subgroup include Baltimore MD, Birmingham AL (excluding hotels, schools, and movie theaters), and Washington DC. Employers in these locations may be affected to the extent that the 1999 NEC, which is the basis for the proposed rulemaking, differs from the 1996 NEC.
Many of the new provisions in the proposed rule, including those in Category 4 that have potential cost implications for new electrical systems and equipment installations, date back to the 1996 NEC or to an NEC prior to 1996. Thus, for these provisions, employers in locations now requiring that the 1996 NEC be followed, will not be affected by OSHA's proposed rulemaking with respect to new installations.
Seven States have not yet adopted any statewide electrical code that applies to all private sector employers. These States include: Alabama (excluding hotels, schools, and movie theaters), Hawaii, Illinois, Kansas, Mississippi, Missouri, and Texas. Employers in these States are expected to be the most affected (of the three subgroups) by OSHA's proposed rulemaking, since no Statewide electrical code is currently required. For these seven States, OSHA's existing electrical installation standard, which is primarily based on the 1971 and 1978 NECs, are the governing regulations.(31) Below the Statewide level, it is not clear to what extent local jurisdictions have passed local electrical ordinances that exceed the 1971 and 1978 NECs and are consistent with the 1999 NEC. While it is likely that some local jurisdictions within these states enforce the 1999 (or 2002) NEC, OSHA's analysis treats these States as though they are not in compliance with either the 1999 or 2002 NEC for purposes of analysis. As a consequence, the estimated compliance costs are likely to be overstated.
Using data from the U.S. Department of Commerce's 1997 County Business Patterns (CBP) database, OSHA has estimated the total number of affected establishments and employment in those establishments for the 58 two-digit SICs covered by general industry electrical safety installation standard.(32) In addition, the number of establishments and employment that are already subject to the 1999 NEC, the 1996 NEC, the 1990 NEC, and no statewide electrical code, are also estimated. For those cities (identified above) that are currently following a particular electrical code, OSHA has estimated the number of establishments and employment in these cities using, as a surrogate, the data for the county in which the cities are located.
The data indicate that there are an estimated 5.6 million establishments with 89.8 million employees in the industries covered by the general industry electrical safety installation standard. About 84.7 percent of the establishments, employing about 85.3 percent of the workers, are in States or cities that have adopted the 1999 (or 2002) NEC. Approximately 6.3 percent of both the establishments and employees are in States or cities that have adopted the 1996 NEC. The remaining approximately 9.0 percent of the establishments, employing about 8.4 percent of the workers, are in States (excluding certain cities in these States) that have not adopted a statewide electrical code applicable to private sector employers. Table 6 summarizes these findings.
C. Benefits
Occupational fatalities associated with electrical accidents remain a significant and ongoing problem. The proposed standard would benefit workers by reducing their exposure to electrical hazards thereby reducing both fatal and nonfatal injuries.
Table 7 presents data from the Survey of Occupational Injuries and Illnesses and the Census of Fatal Occupational Injuries on the number of work-related injuries and deaths in private industry attributed to contact with electrical current for 1992-2002. While the numbers of both injuries and deaths appear to have declined, this decline has not been consistent throughout the time for which data are available. Electrical-related injuries increased between 1992 and 1994, then declined for 1995 to 1997. For 1998 and 1999, injuries again increased. ote that the percentage of occupational injuries associated with electrical hazards has remained essentially constant throughout 1992 to 2001. The number of deaths associated with contact with electrical current declined in 1993, but rose during 1994 and 1995. Deaths dropped in 1996, but rose again in 1997 and 1998. As a percentage of total occupational fatalities, death due to electrocution appears to have remained constant or declined slightly. However, contact with electrical current remains a significant source of occupational fatality, accounting for 5.2 percent of total occupational fatalities in 2002.
For more than 30 years, electrical hazards have been a target of OSHA regulations. The proposed standard will help to further reduce the number of deaths and injuries associated with electrical accidents, and ensure that a downward trend in these incidents is sustained.
To determine the extent to which the proposed standard may reduce the number of deaths attributable to electrical accidents, OSHA examined its accident investigation reports for the States without any statewide electrical code.(33) The most recent and complete reports cover 1990-1996, and provide detailed information on the cause of fatal electrical accidents. The accident cause can be used to ascertain whether the death would have been prevented by compliance with the proposed standard. As an initial screen, OSHA reviewed the reports for accidents that could have been prevented through the use of a GFCI. While OSHA expects that other provisions of the revised standard potentially will reduce deaths due to electrical accidents, this initial screen focused on GFCI-related accidents since they are relatively easy to isolate using a key word search through all reports. Thus, the accident report analysis is conservative in the sense that it likely understates the number of deaths preventable under the proposed revision to Subpart S.
OSHA found that there were at least nine deaths in these seven States during 1990-1996, or an average of 1.3 per year, that could have been prevented with the use of a GFCI. Based on EPA's estimate of a value of $6.1 million for a statistical life, the estimated 1.3 lives saved per year (that is, between 1 and 2 lives saved per year) under the proposed standard would translate to an annual benefit of $6.1 million to $12.2 million.(34) As noted above, the monetized benefits understate total benefits since they do cover all potentially preventable deaths. Moreover, they do not account for any preventable nonfatal injuries.
In addition to quantifiable potential benefits, this update to OSHA's electrical standards yields important unquantified benefits. The revised standard potentially reduces industry confusion and inefficiency associated with the current standard, which is out of date with today's technology. While OSHA has a long standing policy of permitting employers to comply with more current versions of national consensus standards to the extent the more current version is as protective as the older version, this does not address all the concerns with the outdated standard. The older electrical standards may not address the hazards associated with newer equipment and machinery, leaving employers unsure which requirements presently apply. For example, the proposal contains requirements for electric equipment installed in hazardous locations classified under the zone classification system, which is not addressed in the existing standard. (See the summary and explanation of zone classification in section V. F. earlier in the preamble.) The proposed update to Subpart S will reduce or eliminate these problems.
D. Estimation of Compliance Costs
OSHA adopted a conservative approach to estimating compliance costs, and consequently, the estimates reported below are likely to overstate actual compliance costs. In sum, OSHA did not estimate any cost savings associated with the proposed standard, even though many new, potentially less costly alternative compliance methods are being proposed. For example, as noted above, the proposal would permit electric equipment in Class I hazardous locations to be installed under the zone classification system, which is not addressed in the existing standard. Because the hazardous locations provision potentially reduces industry confusion and inefficiency associated with the current standard, costs savings are likely.
For all provisions with the exception of § 1910.304(b)(4)(ii)(A) and (B), cost estimates were developed on a project-level basis. This involved obtaining data on the number of construction and other major renovation, addition, and alteration projects performed annually in States and local jurisdictions that do not now mandate the 1999 NEC (or equivalent).(35) Table 8 summarizes the data on the number of projects potentially impacted by the proposed rule. In States and local jurisdictions that do not now mandate the 1999 NEC (or equivalent), the data indicate that there were a total of 29,306 project starts in 2001, consisting primarily (91 percent) of small projects under $3 million. Less than 0.5 percent of the projects were large projects over $25 million.
For § 1910.304(b)(4)(ii)(A) and (B), compliance costs were estimated on an establishment-level rather than project-level basis. As Table 6 suggests, it is estimated that approximately 861,400 establishments are in locations that either are currently following the 1996 NEC or have not adopted a statewide electrical code applicable to private sector employers. These employers potentially are impacted by the proposed rule. Costs per provision were computed according to establishment size: establishments with fewer than 99 employees, establishments with 100-499 employees, and establishments with more than 500 employees.
All potentially impacted projects/establishments would not necessarily be affected by each and every provision, and some would not be affected at all in any given year. Thus, it was necessary to estimate the percentage of projects/establishments affected by each provision annually. This percentage, when multiplied by the number of potentially impacted projects/establishments yields the number of projects/establishments subject to each provision annually without considering baseline levels of compliance. Table 9 presents the estimated percentage of projects/establishments that actually would be affected by each provision annually. These estimates were based on experience and technical knowledge of electrical practices. OSHA seeks comment on the accuracy of these estimates.
Baseline levels of compliance associated with each of the new provisions also were considered. Baseline levels of compliance were estimated for each provision by considering construction requirements imposed by mortgage lenders and insurance carriers and installation practices routinely followed by licensed electricians (given their formal training). These requirements and installation practices are generally consistent with the current NEC requirements. Moreover, it is expected that these requirements and practices generally become more prevalent as the size of the establishment or project increases. Table 10 presents the estimated percentages for baseline compliance rates. These estimates were based on experience and technical knowledge of electrical practices. OSHA seeks comment on the accuracy of the stimated levels of baseline compliance.
For each provision, estimates of labor and material costs were developed on a project level basis. Labor costs are based on an hourly wage rate of $20.44 for an electrician in the construction sector (SICs 15-17) to perform the work (plus fringe benefits at 37%).(36) Costs for materials, which consist of labels, GFCIs, conduits, connectors, and outlets, are based on data in the Maintenance Direct Catalog of Lab Supply, Inc. (2001). Equipment costs were annualized assuming the useful life of the equipment is two years and an interest rate of 7 percent. Table 11 summarizes the key data and bases for the cost estimates.
Table 12 presents the estimates. The total annual incremental compliance costs associated with the new provisions in the proposed standard, for new electrical system and equipment installations, are estimated to be $9.8 million. The overwhelmingly majority of costs, 81.9 percent, are associated with § 1910.304(b)(4)(ii)(A) and (B). Since these provisions apply to temporary wiring installations, some of the costs and exposures to temporary wiring could potentially be incurred by construction employers instead of general industry employers. This could occur if general industry employers bring in construction companies to make changes in their electrical installations. Temporary wiring requirements for construction work are already covered under Subpart K of Part 1926; and, consequently, this analysis likely overestimates the incremental costs associated with the proposed revisions to Subpart S.
E. Technological and Economic Feasibility
As noted previously, the proposed rule incorporates the NFPA 70E recommendations developed in 2000, which are based on the 1999 NEC. The NFPA 70E Committee has updated the document in accordance with revisions to the NEC, which periodically recodifies acceptable electrical practices as a national consensus standard. As noted earlier, more than 80 percent of establishments covered by the proposed rule are located in areas that currently mandate adherence to these recommendations or the 1999 or more stringent version of the NEC. Moreover, a number of employers comply with the NFPA 70E recommendations in the absence of any legal obligation.(37) Thus, most potentially affected parties already are in compliance with the proposed rule, which clearly demonstrates that it is both technologically and economically feasible.
F. Regulatory Flexibility Screening Analysis and Regulatory Flexibility Certification
In order to determine whether a regulatory flexibility analysis is required under the Regulatory Flexibility Act, OSHA has evaluated the potential economic impacts of this action on small entities. Table 13 presents the data used in this analysis to determine whether this regulation would have a significant impact on a substantial number of small entities.
First, compliance costs were computed on a per establishment basis, which required consideration of the number of establishments potentially impacted. The analysis of CBP data discussed above indicated that approximately 861,400 establishments are in local jurisdictions in the 12 States that are either currently requiring compliance with the 1996 NEC or have not adopted a statewide electrical code applicable to private sector employers. Regarding the documentation provisions for new installations in hazardous locations (§ 1910.307(b) in Table 12), only those industries that handle flammable and/or combustible liquids, vapors, gases, dusts, and/or fibers will be impacted. OSHA identified these industries by reviewing data on § 1910.307 citations issued between October 2000 and September 2001 (available on the OSHA Web site at http://www.osha.gov/oshstats/) and IMIS accident data from 1994 to 2001 indicating § 1910.307 citations (OSHA, 2001). OSHA estimated that approximately 441,400 establishments with hazardous locations are in local jurisdictions in the 12 States that either are currently following the 1996 NEC or have not adopted a statewide electrical code applicable to private sector employers. These are the establishments potentially impacted by the hazardous locations provision. The remaining provisions potentially affect all 861,400 establishments in the 12 States as noted above.
OSHA assumed for purposes of conducting the regulatory flexibility screening analysis, that small firms, on average, will conduct the same type and size of projects as larger establishments. This is a conservative assumption, since it is more likely that smaller establishments will tend to perform small sized, less costly projects. Consequently, OSHA applied average cost per establishment in analyzing effect on small entities. The average cost per establishment was computed by dividing the total costs reported in Table 12 by the number of affected establishments reported in Table 6. For Provisions 1 to 5 and 7, the cost per establishment is $10.44 and for Provision 6, the cost per establishment is $1.92. Thus, for industries that handle flammable and/or combustible liquids, vapors, gases, dusts, and/or fibers, the total cost per establishment is estimated to be $12.36.
OSHA guidelines for determining the need for regulatory flexibility analysis require determining the regulatory costs as a percentage of the revenues and profits of small entities. OSHA derived estimates of the profits and revenues using data from U.S. Census and Dun and Bradstreet. In defining a small business, OSHA followed Small Business Administration (SBA) criteria for each sector. For many of the affected industries, the SBA small business criteria are determined directly by the number of employees. But, for those industries where the SBA small business criteria are not determined by the number of employees (but rather by annual sales), the sales-based criteria were converted to employment-based criteria. Specifically, an employment-based firm size standard was determined by first calculating an employment level, based on the industry average annual receipts per employee, which would be sufficient to produce a total sales amount per firm consistent with the SBA sales-based firm size standard.
As shown in Table 13, at worst, compliance costs represent 0.01 percent of the revenues (for SIC 72, Personal Services) and 0.15 percent of profits (for SIC 56, apparel and Accessory Stores). On average (computed by weighting by number of establishments), compliance costs constitute 0.002 percent of revenues and 0.048 percent of profits. Based on this evaluation, OSHA certifies that this proposed regulation will not have a significant economic impact on a substantial number of small entities.(38)
Table 5.--Proposed Changes to Existing Standard With Cost Implications
Proposed standard Comments on cost impact Types of establishments/projects affected Basis for estimating costs Provisions identified in proposed § 1910.302(b)(4)1
1910.303(h)(5)(iii)(B)
1910.304(b)(4)(ii)(A-B)
1910.308(a)(5)(vi)(B)
910.308(e)(1)(i),
1910.308(e)(1)(ii),
1910.308(e)(1)(iii) Requires the purchase and installation of labels.
Requires the purchase and installation of signs.
Requires the purchase and installation of labels and identification of branch circuits.
Requires the purchase and installation of GFCI in place of standard outlets.
Requires that facility purchase GFCI equipment (power stations or extension cords) for use by maintenance personnel.
Change in design impacts construction cost (near universal compliance assumed).
Facility owner must develop documentation.
Requires the purchase and installation of labels and identification.
Change in facility design and additional materials and installation cost. All Establishments All Projects
All Establishments All Projects
Real Estate Development and Dwelling Projects
Industrial Establishments
All Establishments Large Projects Projects
1 Note: Provisions listed in § 1910.302(b)(4) only apply to new installations.
Table 6. -- Establishments and Employment by Version of NEC Adopted
Applicable version of NEC Establishments Employment
(million) Percent of total Number
(million) Percent of
1999 or 2002
Total 0.4
5.6 100 89.8 100
Source: Compiled from 1997 County Business Patterns database.
Table 7.--Fatal and Nonfatal Occupational Injuries Attributable to Contact With Electric Current
Year Number of injuries involving days away from work Percent of total nonfatal occupational injuries Number of deaths Percent of total fatal occupational injuries
N/A 0.2
N/A=not available.
Source: U.S. Bureau of Labor Statistics, Survey of Occupational Injuries and Illnesses and the Census of Fatal Occupational Injuries (http://www.bls.gov/iif/home.htm).
Table 8.--Construction Project Starts in 2001 for States That Have Adopted the 1996 NEC or Do Not Have a Statewide Electrical Code
Building type Size of project (contract value) Total
Less than $3 million (small) $3-25 million (medium) More than $25 million (large)
Commercial and Public Buildings
Health Facilities and Laboratories
Funeral and Interment Facilities
Athletic and Entertainment Facilities
Auto, Bus, and Truck Service
Apartments, Hotels and Dormitories
Natural Gas Plants
Gas, Water, and Sewer Lines
26562 2618 126 29306
Source: William R. Schriver (2002), The University of Tennessee, Knoxville, Construction Industry Research and Policy Center, based on F.W. Dodge data on construction project starts for 2001.
Table 9.--Estimated Percentages of Potentially Affected Projects/Establishments Actually Affected by Provision and Project/Establishment Size
Provision No. Proposed standard Description of requirement Project/establishment
size (in percent)
7 1910.303(c)(2)(ii)
1910.303(h)(5)(ii)(B)
1910.308(e)(1)(i-iii) Electrical Connections--Terminals
Working Space and Guarding -- Posting of Warning Signs
Branch Circuits -- Identification of Multiwire Branch Circuits
Branch Circuits -- Ground-Fault Circuit Interrupter Protection For Personnel
Temporary Wiring Installations
Swimming Pools, Fountains, and Similar Installations --Receptacles
Hazardous (Classified) Locations--Documentation
Systems Over 600 Volts, Nominal -- Interrupting and Isolating Devices
Fire Alarm Systems-- Power Sources
Communication Systems-- Protective Devices 50
Source: OSHA estimates, based on experience and knowledge of electrical practices.
Table 10.--Estimated Percentages for Baseline Compliance by Provision and Project/Establishment Size
Provision No. Proposed standard Description of requirement Project/establishment size (in percent)
1910.308(e)(1)(i-iii) Electrical Connections -- Terminals
Working Space and Guarding -- Posting of Warning Signs.
Swimming Pools, Fountains, and Similar Installations -- Receptacles
Hazardous (Classified) Locations --Documentation
Fire Alarm Systems -- Power Sources.
Communication Systems -- Protective Devices 25
Table 11.--Data and Bases for Cost Analysis
Provision No. Proposed standard Labor costs Material costs
1910.304(b)(4)(ii)(A)and(B)
1910.308(e)(1)(i),(ii) 1 minute of labor to install label at $28/hour ($20.44 x 1.37)
1 minute of labor to install label at $28/hour ($20.44 x 1.37)
3 hours at $28/hour ($20.44 x 1.37)
1 minute of labor to install . (iii label at $28/hour ($20.44 x 1.37). Cost of label: $1
Cost of label: $1
GFCI: $5
GFCI power station or cord: $55 each, annualized over 2- year useful life
Various conduit, connectors, outlets: $75
Note: The wage rate data are for 2000, taken from the BLS (2001) 2000 National Occupational Employment Statistics (OES) Survey. Fringe benefit rate data are from BLS (2000) Employer Costs for Employee Compensation, March. USDL: 00-186.
Table 12.--Annual Incremental Compliance Costs for Proposed Changes to Subpart S Electrical Standard
Provision No. Proposed
standard Description of requirement Annual costs for projects/establishments 1
Total Small Medium Large
Total 1910.303(c)(2)(ii)
1910.308(e)(1)(i-iii)
.......... Electrical Connections--Terminals
Working Space and Guarding--Posting of Warning Signs
Branch Circuits-- Identification of Multiwire Branch Circuits
Branch Circuits-- Ground-Fault Circuit Interrupter Protection For Personnel
Swimming Pools, Fountains, and Similar Installations- Receptacles
Systems Over 600 Volts, Nominal-- Interrupting and Isolating Devices
Fire Alarm Systems--Power Sources
Systems-Protective Devices
.......... 639,881
Included in Provision 1
756,479 6,545
51,044 8,172 37,593 5,280
9,839,204 9,029,982 588,343 220,879
1 The total cost per establishment is estimated to be $12.36 for industries that handle flammable and/or combustible liquids, vapors, gases, dusts, and/or fibers and $10.44 for all other industries. Source: OSHA estimates
(a) Compliance costs for all provisions except 4 are based on projects. Compliance costs for provision 4 are based on establishments (small establishments have 1-99 employees medium establishments have 100-499 employees, and large establishments have 500+ employees).
(b) Represents the number of projects (or establishments) incurring costs. Factors in both the percentage of projects (or establishments) for which each provision would be applicable, as well as voluntary compliance with each provision.
Table 13.--Impacts on Small Businesses
SIC Industry description Number
of SBA
establishments SBA revenues Revenue
establishment Profit rate (%) Profit
establishment Cost as a percent of revenue Cost as a percent of Profit (in percent)
8900 Agricultural services
General building contractors
Heavy construction, except building
Food And Kindred Products
Textile Mill Products
Apparel And Other Textile Products
Lumber And Wood Products
Paper And Allied Products
Chemicals And Allied Products
Rubber And Misc. Plastics Products
Stone, Clay, And Glass Products
Primary Metal Industries
Fabricated Metal Products
Electronic & Other Electric Equipment
Transportation Equipment
Instruments And Related Products
Miscellaneous Manufacturing Industries
Local and interurban passenger transit
Trucking And Warehousing
Transportation by air
Pipelines, Except Natural Gas
Electric, Gas, And Sanitary Services
Wholesale Trade--Durable Goods
Wholesale Trade--Nondurable Goods
Building Materials & Garden Supplies
Automotive Dealers & Service Stations
Furniture And Homefurnishings Stores
Nondepository Institutions
Insurance Agents, Brokers, & Service
Hotels And Other Lodging Places
Auto Repair, Services, and Parking
Miscellaneous Repair Services
Amusement & Recreation Services
Museums, Botanical, Zoological Gardens
Engineering and management services
Services, n.e.c. 109,663
16,395 $38,501,047
8,169,059 $351,085
498,265 6.02
6.80 $21,130
33,882 0.0030
The 26 States or territories with OSHA-approved occupational safety and health plans must adopt an equivalent amendment or one that is at least as protective to employees within 6 months of the publication date of the final standard. These are: Alaska, Arizona, California, Connecticut (for State and local government employees only), Hawaii, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Nevada, New Mexico, New Jersey (for State and local government employees only), New York (for State and local government employees only), North Carolina, Oregon, Puerto Rico, South Carolina, Tennessee, Utah, Vermont, Virginia, Virgin Islands, Washington, and Wyoming.
The proposed standard's provisions have been reviewed in accordance with the requirements of the National Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321, et seq.), the regulations of the Council on Environmental Quality (40 CFR Part 1502), and the Department of Labor's NEPA procedures (29 CFR Part 11). As a result of this review, OSHA has determined that these provisions will have no significant effect on air, water or soil quality, plant or animal life, on the use of land, or other aspects of the environment.
This proposed rule has been reviewed in accordance with the Unfunded Mandates Reform Act of 1995 (UMRA) (2 U.S.C. 1501 et seq.). For the purposes of the UMRA, the Agency certifies that this proposed rule does not impose any Federal mandate that may result in increased expenditures by State, local, or tribal governments, or increased expenditures by the private sector, of more than $100 million in any year.
OSHA has reviewed this proposed rule in accordance with the Executive Order on Federalism (Executive Order 13132, 64 FR 43255, August 10, 1999), which requires that agencies, to the extent possible, refrain from limiting State policy options, consult with States prior to taking any actions that would restrict State policy options, and take such actions only when there is clear constitutional authority and the presence of a problem of national scope. The Order provides for preemption of State law only if there is a clear Congressional intent for the Agency to do so. Any such preemption is to be limited to the extent possible.
Section 18 of the OSH Act expresses Congress's intent to preempt State laws where OSHA has promulgated occupational safety and health standards. A State can avoid preemption on issues covered by Federal standards only if it submits, and obtains Federal approval of, a plan for the development of such standards and their enforcement. 29 U.S.C. 667, Gade v. National Solid Wastes Management Association, 505 U.S. 88 (1992). Occupational safety and health standards developed by such Plan States must, among other things, be at least as effective in providing safe and healthful employment and places of employment as the Federal standards. Subject to the statutory limitations of the OSH Act, State-Plan States are free to develop and enforce their own requirements for occupational safety and health protections related to electrical installation.
Although OSHA has a clear statutory mandate to preempt state occupational safety and health laws, the proposed standard would introduce few new requirements that are not already mandated by applicable State and local law. As discussed above in the Economic Analysis, most States and municipalities require compliance with the NEC, which is consistent with the proposed rule.
The proposed Electrical Standard contains collection-of-information (paperwork) requirements that are subject to review by the Office of Management and Budget (OMB) under the Paperwork Reduction Act of 1995 (PRA-95), 44 U.S.C. 3501 et seq., and OMB's regulations at 5 CFR part 1320. The Paperwork Reduction Act defines "collection of information" as "the obtaining, causing to be obtained, soliciting, or requiring the disclosure to third parties or the public of facts or opinions by or for an agency regardless of form or format * * *" (44 U.S.C. 3502(3)(A)). OMB is currently reviewing OSHA's request for approval of the proposed collections. OSHA solicits comments on the collection-of-information requirements and the estimated burden hours associated with these collections, including comments on the following:
Whether the proposed information-collection requirements are necessary for the proper performance of the Agency's functions, including whether the information is useful;
The accuracy of OSHA's estimate of the burden (time and cost) of the information-collection requirements, including the validity of the methodology and assumptions used;
The quality, utility, and clarity of the information collected; and
Ways to minimize the burden on employers who must comply, for example, by using automated or other technological techniques for collecting and transmitting information.
The title, description of the need for and proposed use of the information, description of the respondents, and frequency of response of the information collections are described below with an estimate of the annual reporting burden and cost as required by § 1320.5(a)(1)(iv) and § 1320.8(d)(2).
Title: Design Safety Standards for Electrical Systems (§ § 1910.302 through 1910.308).
Description and Proposed use of the collections of information: The proposed standard would impose new information collection requirements for purposes of the PRA. These collection of information requirements in the proposal (§ § 1910.303(f)(5)(i), 1910.303(f)(5)(ii), 1910.304(b)(1), 1910.304(b)(3), 1910.306(c)(6)(i), 1910.306(c)(6)(ii), 1910.306(k)(4)(iv)(B), 1910.307(b), 1910.308(b)(3)(i), and 1910.308(b)(3)(ii)) have not been approved by the Office of Budget and Management (OMB). These provisions are needed to provide electrical safety to employees against the electric shock hazards that might be present in the workplace. The marking of electrical equipment with the proper ratings, identifying the phase and system of each ungrounded conductor, identifying the disconnecting means with a sign for the location, or documenting hazardous classified areas are all ways of reducing the electrical hazards pose on employees. OSHA will use the records developed in response to this standard to determine compliance. The employer's failure to generate and disclose the information required in this Standard will affect significantly OSHA's effort to control and reduce injuries and fatalities related to electrical hazards in the workplace.
Summary of the Collections of Information: The following are new collections of information contained in the Design Safety Standards for Electrical Systems (§ § 1910.302 through 1910.308).
Section 1910.303 Marking Requirements for Series Combination Ratings
Paragraphs (f)(5)(i) and (ii) of this section require the employer to mark in the indicated field the circuit breakers' and fuses' series combination ratings of the equipment given by the manufacture. The wording shall state "Caution -- Series Combination System Rated ---- Amperes. Identified Replacement Component Required." The employer has to legibly mark in the blank to indicate the rating.
Section 1910.304 Wiring Design and Protection
Paragraph (b)(1) of this section requires the employer to identify the phase and system of each ungrounded conductor of a multiwire branch circuit in a building containing more than one nominal voltage system. This marking is required to be permanently posted on each panelboard.
Paragraph (b)(3) requires the employer to identify the phase and system of each ungrounded system conductor in a building where there is more than one nominal voltage system. The identification is required to be permanently posted at each branch circuit panelboard.
Section 1910.306 Specific Purpose Equipment and Installations
Paragraph (c)(6)(i) requires the employer to identify the disconnecting means with the number that corresponds to the driving machine number that it controls where there is more than one driving machine in the machine room.
Paragraph (c)(6)(ii) requires the employer to provide the disconnecting means with a sign to identify the location of the supply-side overcurrent protective device.
Paragraph (k)(4)(iv)(B) requires the employer to mark the systems to which single-pole separable connectors used in portable professional motion picture and television equipment are connected if the connectors are interchangeable for ac or dc use or for different current ratings on the same premises.
Section 1910.307 Hazardous (Classified) Locations
Paragraph (b) requires the employer to properly document all areas designated as hazardous (classified) locations. This documentation shall be available to those authorized to design, install, inspect, maintain, or operate electric equipment at the location.
Section 1910.308 Special Systems
Paragraph (b)(3)(i) requires the employer to place a sign at the service entrance equipment indicating the type and location of on-site emergency power sources. A sign is not required for individual unit equipment.
Paragraph (b)(3)(ii) requires a sign at the grounding location that identifies all emergency and normal sources connected at the location.
Respondents: Employers who design, install, or use electrical installations and utilization equipment within or on buildings, structures, and other premises.
Frequency of Response: On occasion. Most of the collections of information are markings, labels or signs that provide information to protect employees against the electric shock hazards that might be present in the workplace. The collections of information are completed at the time electrical work is being performed.
Average Time per Response: Time per response varies from one minute for an engineering manager to brief the technician on the type and location of on-site emergency power sources to 4 hours for an electrical certified electrical engineer to determine and document all areas designated as hazardous (classified) location.
Total Burden Hours: 8,157.
Estimated Costs (Operating and Maintenance): -0-.
Interested parties who wish to comment on the paperwork requirements in this proposal must send their written comments to the OSHA Docket Office, Docket No. S-108C, Occupational Safety and Health, Room N-2625, 200 Constitution Avenue, NW., Washington, DC 20210, and to the Office of Information and Regulatory Affairs, New Executive Office Building, Office of Management and Budget, Room 10235, 725 17th Street, NW., Washington, DC 20503, Attn: OSHA Desk Officer (RIN 1218-AB95)). The Agency also encourages commenters to include their comments on paperwork requirements with their other comments on the proposed rule submitted to OSHA.
The Agency requests members of the public to submit written comments and other information concerning this proposal. These comments may include objections to the proposal with or without a hearing request, as well as comments that endorse or support the proposed amendment set forth in this notice. OSHA welcomes such comments and information so that the record of this rulemaking will represent a balanced public response on the issues involved. OSHA is particularly interested in receiving comments that address provisions of the proposed rule that differ from those in existing Subpart S. See the sections above titled DATES and ADDRESSES for information on submitting these comments and information to the Agency. Submissions received within the specified comment period will become part of the record, and will be available for public inspection and copying in the OSHA Docket Office.
Under section 6(b)(3) of the OSH Act and 29 CFR 1911.11, members of the public may request an informal hearing by following the instructions under the section of this Federal Register notice titled ADDRESSES. These requests must include the objections to the proposal that warrant a hearing. The party making objections that are part of a hearing request must:
Include their name and address;
Ensure that the request is sent or postmarked no later than June 4, 2004;
Number each objection separately;
Specify with particularity the grounds for each objection;
Include a detailed summary of the evidence supporting each objection which they plan to offer at the requested hearing.
This document was prepared under the direction of John Henshaw, Assistant Secretary of Labor for Occupational Safety and Health, 200 Constitution Avenue, NW., Washington, DC 20210.
This action is taken pursuant to sections 4, 6, and 8 of the Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 657), Secretary of Labor's Order No. 5-2002 (67 FR 65008), and 29 CFR Part 1911.
Signed at Washington, DC, this 23rd day of March, 2004.
John Henshaw,
Assistant Secretary of Labor.
It is proposed to amend Part 1910 of Title 29 of the Code of Federal Regulations as follows:
Subpart F--[Amended]
1. The authority citation for Subpart F would be revised to read as follows:
Authority: Secs. 4, 6, and 8 of the Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), or 5-2002 (67 FR 65008), as applicable; and 29 CFR part 1911.
Appendix D to § 1910.66 [Amended]
2. Appendix D to § 1910.66 would be amended as follows:
a. The words "the National Electrical Code, NFPA 70-1971; ANSI C1-1971 (Rev. of C1-1968)" would be revised to read "subpart S of this part" in paragraph (c)(22)(i).
b. The words "Article 610 of the National Electrical Code, NFPA 70-1971; ANSI C1--1971 (Rev. of C1-1968)" would be revised to read "subpart S of this part" in paragraph (c)(22)(vii).
Subpart S--[Amended]
3. The authority citation for Subpart S would be revised to read as follows:
Authority: Secs. 4, 6, 8, Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 657); Secretary of Labor's Order No. 8-76 (41 FR 25059), 1-90 (55 FR 9033), or 5-2002 (67 FR 65008), as applicable; 29 CFR part 1911.
4. Sections 1910.302 through 1910.308 would be revised to read as follows:
Design Safety Standards for Electrical Systems
§ 1910.302 Electric utilization systems.
Sections 1910.302 through 1910.308 contain design safety standards for electric utilization systems.
(a) Scope -- (1) Covered. The provisions of § § 1910.302 through 1910.308 of this subpart cover electrical installations and utilization equipment installed or used within or on buildings, structures, and other premises including:
(i) Yards,
(ii) Carnivals,
(iii) Parking and other lots,
(iv) Mobile homes,
(v) Recreational vehicles,
(vi) Industrial substations,
(vii) Conductors that connect the installations to a supply of electricity, and
(viii) Other outside conductors on the premises.
(2) Not covered. The provisions of § § 1910.302 through 1910.308 of this subpart do not cover:
(i) Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles.
(ii) Installations underground in mines.
(iii) Installations of railways for generation, transformation, transmission, or distribution of power used exclusively for operation of rolling stock or installations used exclusively for signaling and communication purposes.
(iv) Installations of communication equipment under the exclusive control of communication utilities, located outdoors or in building spaces used exclusively for such installations.
(v) Installations under the exclusive control of electric utilities for the purpose of communication or metering; or for the generation, control, transformation, transmission, and distribution of electric energy located in buildings used exclusively by utilities for such purposes or located outdoors on property owned or leased by the utility or on public highways, streets, roads, etc., or outdoors by established rights on private property.
(b) Extent of application -- (1) Requirements applicable to all installations. The following requirements apply to all electrical installations and utilization equipment, regardless of when they were designed or installed:
§ 1910.303(b)
§ 1910.303(d)
§ 1910.303(e)
§ 1910.303(f), except (f)(4)and (f)(5)
§ 1910.303(g)(2)
§ 1910.304(f)(1)(i), (f)(1)(iv), and(f)(1)(v)
§ 1910.304(g)(1)(ii), (g)(1)(iii), (g)(1)(iv), and (g)(1)(v)
§ 1910.304(g)(5)(iv)(A) through (g)(5)(iv)(D), and (g)(5)(vi)
§ 1910.304(g)(7)(i)
§ 1910.305(g)(2)(ii) and (g)(2)(iii)
§ 1910.307 Examination, installation, and use of equipment.
Electrical connections -- Splices.
Arcing parts.
Marking.
Disconnecting means and circuits.
600 volts or less--Guarding of live parts.
Overcurrent protection--600volts, nominal, or less.
Grounding--Systems to be grounded.
Grounding--Grounding connections.
Grounding--Grounding path.
Grounding--Supports enclosures, and equipment to be grounded.
Grounding--Nonelectrical equipment.
Grounding--Methods of grounding fixed equipment.
Flexible cords and cables--Use of flexible cords and cables.
Flexible cords and cables-- Identification, splices, and terminations.
Hazardous (classified) locations.
(2)Requirements applicable to installations made after March 15, 1972. Every electrical installation and all utilization equipment installed or overhauled after March 15, 1972, shall comply with the provisions of § § 1910.302 through 1910.308, except as noted in paragraphs (b)(3) and (b)(4) of this section.
(3) Requirements applicable only to installations made after April 16, 1981. The following requirements apply only to electrical installations and utilization equipment installed after April 16, 1981:
§ 1910.303(h)(4)
§ 1910.304(f)(1)(vii) and (f)(1)(viii)
§ 1910.305(j)(6)(ii)(D
§ 1910.306(i)
§ 1910.306(j)(5)
§ 1910.308(a)(1)(ii)
§ 1910.308(d) Over 600 volts, nominal-- Entrance and access to work space.
Overcurrent protection--600 volts, nominal, or less.
Grounding--Grounding of systems and circuits of 1000 volts and over (high voltage).
Equipment for general use-- Capacitors.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts--Interconnection between multicar controllers.
Electrically driven or controlled irrigation machines.
Swimming pools, fountains, and similar installations-- Fountains.
Systems over 600 volts, nominal--Aboveground wiring methods.
Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits-- Marking.
Fire alarm systems.
(4) Requirements applicable only to installations made after the effective date of the final rule. The following requirements apply only to electrical installations and utilization equipment installed after the effective date of the final rule:
§ 1910.303(f)(4)
§ 1910.303(g)(1)(iv) and (g)(1)(vii)
§ 1910.303(h)(5)(vi)
§ 1910.304(b)(4)(i)
§ 1910.304(f)(2)(i)(A), (f)(2)(i)(B) (but not the introductorytext to § 1910.304(f)(2)(i)), and (f)(2)(iv)(A).
§ 1910.305(a)(3)(v)
§ 1910.305(c)(3)(ii)
§ 1910.306(j)(1)(iii)
§ 1910.306(k)
§ 1910.308(a)(5)(v) and (a)(5)(vi)(B)
§ 1910.308(a)(7)(vi)
§ 1910.308(f) Disconnecting means and circuits--Capable of accepting a lock.
Disconnecting means and circuits--Marking for series combination ratings.
600 Volts, nominal, or less-- Space about electric equipment.
Over 600 volts, nominal-- Working space and guarding.
Branch circuits--Identification of multiwire branch circuits.
Branch circuits--Identification of ungrounded conductors.
Branch circuits--Ground-fault circuit interrupter protection for personnel.
Overcurrent protection--Feeders and branch circuits over 600 volts, nominal.
Wiring methods--Cable trays.
Switches--Connection of switches.
Switches--Grounding.
Electric signs and outline lighting--Disconnecting means.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts--Operation.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts--Location.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts--Identification and signs.
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts--Single-car and multicar installations.
Swimming pools, fountains, and similar installations-- Receptacles.
Carnivals, circuses, fairs, and similar events.
Systems over 600 volts, nominal--Interrupting and isolating devices.
Systems over 600 volts, nominal--Tunnel installations.
Emergency power systems--Signs.
Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits-- Separation from conductors of other circuits.
Solar photovoltaic systems.
(c) Applicability of requirements for disconnecting means. The requirement in § 1910.147(c)(2)(iii) that energy isolating devices be capable of accepting a lockout device whenever replacement or major repair, renovation or modification of a machine or equipment is performed, and whenever new machines or equipment are installed after January 2, 1990, applies in addition to any requirements in § 1910.303 through § 1910.308 that disconnecting means be capable of being locked in the open position under certain conditions.
§ 1910.303 General.
(a) Approval. The conductors and equipment required or permitted by this subpart shall be acceptable only if approved, as defined in § 1910.399.
(b) Examination, installation, and use of equipment -- (1) Examination. Electric equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees. Safety of equipment shall be determined using the following considerations:
(i) Suitability for installation and use in conformity with the provisions of this subpart;
Note to paragraph (b)(1)(i) of this section: Suitability of equipment for an identified purpose may be evidenced by listing or labeling for that identified purpose.
(ii) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided;
(iii) Wire-bending and connection space;
(iv) Electrical insulation;
(v) Heating effects under all conditions of use;
(vi) Arcing effects;
(vii) Classification by type, size, voltage, current capacity, and specific use; and
(viii) Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment.
(2) Installation and use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
(3) Insulation integrity. Completed wiring installations shall be free from short circuits and from grounds other than those required or permitted by this subpart.
(4) Interrupting rating. Equipment intended to interrupt current at fault levels shall have an interrupting rating sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment. Equipment intended to interrupt current at other than fault levels shall have an interrupting rating at nominal circuit voltage sufficient for the current that must be interrupted.
(5) Circuit impedance and other characteristics. The overcurrent protective devices, the total impedance, the component short-circuit current ratings, and other characteristics of the circuit to be protected shall be selected and coordinated to permit the circuit protective devices used to clear a fault to do so without the occurrence of extensive damage to the electrical components of the circuit. This fault shall be assumed to be either between two or more of the circuit conductors, or between any circuit conductor and the grounding conductor or enclosing metal raceway.
(6) Deteriorating agents. Unless identified for use in the operating environment, no conductors or equipment shall be located in damp or wet locations; where exposed to gases, fumes, vapors, liquids, or other agents that have a deteriorating effect on the conductors or equipment; or where exposed to excessive temperatures.
(7) Mechanical execution of work. Electric equipment shall be installed in a neat and workmanlike manner.
(i) Unused openings in boxes, raceways, auxiliary gutters, cabinets, equipment cases, or housings shall be effectively closed to afford protection substantially equivalent to the wall of the equipment.
(ii) Conductors shall be racked to provide ready and safe access in underground and subsurface enclosures that persons enter for installation and maintenance.
(iii) Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces may not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues.
(iv) There shall be no damaged parts that may adversely affect safe operation or mechanical strength of the equipment, such as parts that are broken, bent, cut, or deteriorated by corrosion, chemical action, or overheating.
(8) Mounting and cooling of equipment. (i) Electric equipment shall be firmly secured to the surface on which it is mounted.
Note to paragraph (b)(8)(i) of this section: Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials are not considered secure means of fastening electric equipment.
(ii) Electric equipment that depends on the natural circulation of air and convection principles for cooling of exposed surfaces shall be installed so that room airflow over such surfaces is not prevented by walls or by adjacent installed equipment. For equipment designed for floor mounting, clearance between top surfaces and adjacent surfaces shall be provided to dissipate rising warm air.
(iii) Electric equipment provided with ventilating openings shall be installed so that walls or other obstructions do not prevent the free circulation of air through the equipment.
(c) Electrical connections -- (1) General. Because of different characteristics of dissimilar metals:
(i) Devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used.
(ii) Conductors of dissimilar metals may not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum) unless the device is identified for the purpose and conditions of use.
(iii) Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.
(2) Terminals. (i) Connection of conductors to terminal parts shall ensure a good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads. However, No. 10 or smaller conductors may be connected by means of wire binding screws or studs and nuts having upturned lugs or equivalent.
(ii) Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.
(3) Splices. (i) Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined to be mechanically and electrically secure without solder and then soldered. All splices and joints and the free ends of conductors shall be covered with an insulation equivalent to that of the conductors or with an insulating device identified for the purpose.
(ii) Wire connectors or splicing means installed on conductors for direct burial shall be listed for such use.
(d) Arcing parts. Parts of electric equipment that in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from all combustible material.
(e) Marking -- (1) Identification of manufacturer and ratings. Electric equipment may not be used unless the following markings have been placed on the equipment:
(i) The manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the product may be identified; and
(ii) Other markings giving voltage, current, wattage, or other ratings as necessary.
(2) Durability. The marking shall be of sufficient durability to withstand the environment involved.
(f) Disconnecting means and circuits -- (1) Motors and appliances. Each disconnecting means required by this subpart for motors and appliances shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident.
(2) Services, feeders, and branch circuits. Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident.
(3) Durability of markings. The markings required by paragraphs (f)(1) and (f)(2) of this section shall be of sufficient durability to withstand the environment involved.
(4) Capable of accepting a lock. Disconnecting means required by this subpart shall be capable of being locked in the open position.
(5) Marking for series combination ratings. (i) Where circuit breakers or fuses are applied in compliance with the series combination ratings marked on the equipment by the manufacturer, the equipment enclosures shall be legibly marked in the field to indicate that the equipment has been applied with a series combination rating.
(ii) The marking required by paragraph (f)(5)(i) of this section shall be readily visible and shall state "Caution--Series Combination System Rated ______ Amperes. Identified Replacement Component Required."
(g) 600 volts, nominal, or less. The following requirements apply to electric equipment operating at 600 volts, nominal, or less to ground:
(1) Space about electric equipment. Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.
(i) Working space for equipment likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the following dimensions, except as required or permitted elsewhere in this subpart:
(A) The depth of the working space in the direction of access to live parts may not be less than indicated in Table S-1. Distances shall be measured from the live parts if they are exposed or from the enclosure front or opening if they are enclosed.
(B) The width of working space in front of the electric equipment shall be the width of the equipment or 762 mm (30 in.), whichever is greater. In all cases, the working space shall permit at least a 90-degree opening of equipment doors or hinged panels.
(C) The work space shall be clear and extend from the grade, floor or platform to the height required by paragraph (g)(1)(vi) of this section. However, other equipment associated with the electrical installation and located above or below the electric equipment may extend not more than 153 mm (6 in.) beyond the front of the electric equipment.
(ii) Working space required by this standard may not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.
(iii) At least one entrance of sufficient area shall be provided to give access to the working space about electric equipment.
(iv) For equipment rated 1200 amperes or more and over 1.83 m (6.0 ft) wide, containing overcurrent devices, switching devices, or control devices, there shall be one entrance not less than 610 mm (24 in.) wide and 1.98 m (6.5 ft) high at each end of the working space. Where the location permits a continuous and unobstructed way of exit travel, one means of exit is permitted. Where the working space required by paragraph (g)(1)(i) of this section is doubled, only one entrance to the working space is required, and the entrance shall be located so that the edge of the entrance nearest the equipment is the minimum clear distance given in Table S-1 away from such equipment.
(v) Illumination shall be provided for all working spaces about service equipment, switchboards, panelboards, and motor control centers installed indoors. Additional lighting fixtures are not required where the working space is illuminated by an adjacent light source. In electric equipment rooms, the illumination may not be controlled by automatic means only.
(vi) The minimum headroom of working spaces about service equipment, switchboards, panelboards, or motor control centers shall be as follows:
(A) For installations built before the effective date of the final rule, 1.91 m (6.25 ft); and
(B) For installations built on or after the effective date of the final rule, 1.98 m (6.5 ft), except that where the electrical equipment exceeds 1.98 m (6.5 ft) in height, the minimum headroom may not be less than the height of the equipment.
Table S-1.--Minimum Depth of Clear Working Space at Electric Equipment, 600 V or Less
Nominal voltage to ground Minimum clear distance for condition 2 3
Condition A Condition B Condition C
m ft m ft m ft
0--150
151--600 10.9
Notes to Table S-1:
1 Minimum clear distances may be 0.7 m (2.5 ft) for installations built before April 16, 1981.
2 Conditions A, B, and C are as follows:
Condition A--Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating material. Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts.
Condition B--Exposed live parts on one side and grounded parts on the other side.
Condition C--Exposed live parts on both sides of the work space (not guarded as provided in Condition A) with the operator between.
3 Working space is not required in back of assemblies such as dead-front switchboards or motor control centers where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on deenergized parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) horizontally shall be provided.
(vii) Switchboards, panelboards, and distribution boards installed for the control of light and power circuits, and motor control centers shall be located in dedicated spaces and protected from damage.
(A) For indoor installation, the dedicated space shall comply with the following:
(1) The space equal to the width and depth of the equipment and extending from the floor to a height of 1.83 m (6.0 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. Unless isolated from equipment by height or physical enclosures or covers that will afford adequate mechanical protection from vehicular traffic or accidental contact by unauthorized personnel or that complies with paragraph (g)(1)(vii)(A)(2) of this section, piping, ducts, or equipment foreign to the electrical installation may not be located in this area.
(2) The space equal to the width and depth of the equipment shall be kept clear of foreign systems unless protection is provided to avoid damage from condensation, leaks, or breaks in such foreign systems. This area shall extend from the top of the electric equipment to the structural ceiling.
(3) Sprinkler protection is permitted for the dedicated space where the piping complies with this section.
(4) Control equipment that by its very nature or because of other requirements in this subpart must be adjacent to or within sight of its operating machinery is permitted in the dedicated space.
Note to paragraph (g)(1)(vii)(A) of this section: A dropped, suspended, or similar ceiling that does not add strength to the building structure is not considered a structural ceiling.
(B) Outdoor electric equipment shall be installed in suitable enclosures and shall be protected from accidental contact by unauthorized personnel, or by vehicular traffic, or by accidental spillage or leakage from piping systems. No architectural appurtenance or other equipment may be located in the working space required by paragraph (g)(1)(i) of this section.
(2) Guarding of live parts. (i) Except as elsewhere required or permitted by this standard, live parts of electric equipment operating at 50 volts or more shall be guarded against accidental contact by use of approved cabinets or other forms of approved enclosures or by any of the following means:
(A) By location in a room, vault, or similar enclosure that is accessible only to qualified persons.
(B) By suitable permanent, substantial partitions or screens so arranged so that only qualified persons will have access to the space within reach of the live parts. Any openings in such partitions or screens shall be so sized and located that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them.
(C) By placement on a suitable balcony, gallery, or platform so elevated and otherwise located as to prevent access by unqualified persons.
(D) By elevation of 2.44 m (8.0 ft) or more above the floor or other working surface.
(ii) In locations where electric equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.
(iii) Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.
(h) Over 600 volts, nominal -- (1) General. Conductors and equipment used on circuits exceeding 600 volts, nominal, shall comply with all applicable provisions of the paragraphs (a) through (g) of this section and with the following provisions, which supplement or modify the preceding requirements. However, paragraphs (h)(2), (h)(3), and (h)(4) of this section do not apply to the equipment on the supply side of the service point.
(2) Enclosure for electrical installations. (i) Electrical installations in a vault, room, or closet or in an area surrounded by a wall, screen, or fence, access to which is controlled by lock and key or other approved means, are considered to be accessible to qualified persons only. The type of enclosure used in a given case shall be designed and constructed according to the hazards associated with the installation.
(ii) For installations other than equipment described in paragraph (h)(2)(v) of this section, a wall, screen, or fence shall be used to enclose an outdoor electrical installation to deter access by persons who are not qualified. A fence may not be less than 2.13 m (7.0 ft) in height or a combination of 1.80 m (6.0 ft) or more of fence fabric and a 305-mm (1-ft) or more extension utilizing three or more strands of barbed wire or equivalent.
(iii) The following requirements apply to indoor installations that are accessible to other than qualified persons:
(A) The installations shall be made with metal-enclosed equipment or shall be enclosed in a vault or in an area to which access is controlled by a lock.
(B) Metal-enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs.
(C) Openings in ventilated dry-type transformers and similar openings in other equipment shall be designed so that foreign objects inserted through these openings will be deflected from energized parts.
(iv) Outdoor electrical installations having exposed live parts shall be accessible to qualified persons only.
(v) The following requirements apply to outdoor enclosed equipment accessible to unqualified employees:
(A) Ventilating or similar openings in equipment shall be so designed that foreign objects inserted through these openings will be deflected from energized parts.
(B) Where exposed to physical damage from vehicular traffic, suitable guards shall be provided.
(C) Nonmetallic or metal-enclosed equipment located outdoors and accessible to the general public shall be designed so that exposed nuts or bolts cannot be readily removed, permitting access to live parts.
(D) Where nonmetallic or metal-enclosed equipment is accessible to the general public and the bottom of the enclosure is less than 2.44 m (8.0 ft) above the floor or grade level, the enclosure door or hinged cover shall be kept locked.
(E) Except for underground box covers that weigh over 45.4 kg (100 lb), doors and covers of enclosures used solely as pull boxes, splice boxes, or junction boxes shall be locked, bolted, or screwed on.
(3) Work space about equipment. Sufficient space shall be provided and maintained about electric equipment to permit ready and safe operation and maintenance of such equipment. Where energized parts are exposed, the minimum clear work space may not be less than 1.98 m (6.5 ft) high (measured vertically from the floor or platform) or less than 914 mm (3.0 ft) wide (measured parallel to the equipment). The depth shall be as required in paragraph (h)(5)(i) of this section. In all cases, the work space shall be adequate to permit at least a 90-degree opening of doors or hinged panels.
(4) Entrance and access to work space. (i) At least one entrance not less than 610 mm (24 in.) wide and 1.98 m (6.5 ft) high shall be provided to give access to the working space about electric equipment.
(A) On switchboard and control panels exceeding 1.83 m (6.0 ft) in width, there shall be one entrance at each end of such boards unless the location of the switchboards and control panels permits a continuous and unobstructed way of exit travel, or unless the work space required in paragraph (h)(5)(i) of this section is doubled.
(B) Where one entrance to the working space is permitted under the conditions described in paragraph (h)(4)(i)(A) of this section, the entrance shall be located so that the edge of the entrance nearest the switchboards and control panels is the minimum clear distance given in Table S-2 away from such equipment.
(C) Where bare energized parts at any voltage or insulated energized parts above 600 volts, nominal, to ground are located adjacent to such entrance, they shall be suitably guarded.
(ii) Permanent ladders or stairways shall be provided to give safe access to the working space around electric equipment installed on platforms, balconies, mezzanine floors, or in attic or roof rooms or spaces.
(5) Working space and guarding. (i) Except as elsewhere required or permitted in this subpart, the minimum clear working space in the direction of access to live parts of electric equipment may not be less than specified in Table S-2. Distances shall be measured from the live parts, if they are exposed, or from the enclosure front or opening, if they are enclosed.
(ii) If switches, cutouts, or other equipment operating at 600 volts, nominal, or less, are installed in a room or enclosure where there are exposed live parts or exposed wiring operating at over 600 volts, nominal, the high-voltage equipment shall be effectively separated from the space occupied by the low-voltage equipment by a suitable partition, fence, or screen. However, switches or other equipment operating at 600 volts, nominal, or less, and serving only equipment within the high-voltage vault, room, or enclosure may be installed in the high-voltage enclosure, room, or vault if accessible to qualified persons only.
(iii) The following requirements apply to the entrances to all buildings, rooms, or enclosures containing exposed live parts or exposed conductors operating at over 600 volts, nominal:
(A) The entrances shall be kept locked unless they are under the observation of a qualified person at all times.
(B) Permanent and conspicuous warning signs shall be provided, reading substantially as follows:
"DANGER -- HIGH VOLTAGE - KEEP OUT."
(iv) Illumination shall be provided for all working spaces about electric equipment.
(A) The lighting outlets shall be arranged so that persons changing lamps or making repairs on the lighting system will not be endangered by live parts or other equipment.
(B) The points of control shall be located so that persons are prevented from contacting any live part or moving part of the equipment while turning on the lights.
(v) Unguarded live parts above working space shall be maintained at elevations not less than specified in Table S-3.
(vi) Pipes or ducts that are foreign to the electrical installation and that require periodic maintenance or whose malfunction would endanger the operation of the electrical system may not be located in the vicinity of service equipment, metal-enclosed power switchgear, or industrial control assemblies. Protection shall be provided where necessary to avoid damage from condensation leaks and breaks in such foreign systems.
Note to paragraph (h)(5)(vi) of this section: Piping and other facilities are not considered foreign if provided for fire protection of the electrical installation.
Table S-2. -- Minimum Depth of Clear Working Space at Electric Equipment, Over 600 V
601-2500 V
2501-9000 V
9001 V-25 kV
Over 25-75 kV
Above 75 kV 0.9
1 Minimum depth of clear working space in front of electric equipment with a nominal voltage to ground above 25,000 volts may be the same as that for 25,000 volts under Conditions A, B, and C for installations built before April 16, 1981.
Condition B--Exposed live parts on one side and grounded parts on the other side. Concrete, brick, and tile walls are considered as grounded surfaces.
3 Working space is not required in back of equipment such as dead-front switchboards or control assemblies that has no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on the deenergized parts on the back of enclosed equipment, a minimum working space 762 mm (30 in.) horizontally shall be provided.
Table S-3.--Elevation of Unguarded Live Parts Above Working Space
Nominal voltage between phases Elevation
m ft
over 35 kV 2.81
2.8 + 9.5 mm/kV over 35 kV
9.0 + 0.37 in./kV 35 kV
1 The minimum elevation may be 2.6 m (8.5 ft) for installations built before the effective date of the standard.
(a) Use and identification of grounded and grounding conductors -- (1) Identification of conductors. (i) A conductor used as a grounded conductor shall be identifiable and distinguishable from all other conductors.
(ii) A conductor used as an equipment grounding conductor shall be identifiable and distinguishable from all other conductors.
(2) Polarity of connections. No grounded conductor may be attached to any terminal or lead so as to reverse designated polarity.
(3) Use of grounding terminals and devices. A grounding terminal or grounding-type device on a receptacle, cord connector, or attachment plug may not be used for purposes other than grounding.
(b) Branch circuits -- (1) Identification of multiwire branch circuits. Where more than one nominal voltage system exists in a building containing multiwire branch circuits, each ungrounded conductor of a multiwire branch circuit, where accessible, shall be identified by phase and system. The means of identification shall be permanently posted at each branch-circuit panelboard.
(2) Receptacles and cord connectors. (i) Receptacles installed on 15- and 20-ampere branch circuits shall be of the grounding type except as permitted for replacement receptacles in paragraph (b)(2)(iv) of this section. Grounding-type receptacles shall be installed only on circuits of the voltage class and current for which they are rated, except as provided in Table S-4 and Table S-5.
(ii) Receptacles and cord connectors having grounding contacts shall have those contacts effectively grounded except for receptacles mounted on portable and vehicle-mounted generators in accordance with paragraph (g)(2) of this section and replacement receptacles installed in accordance with paragraph (b)(2)(iv) of this section.
(iii) The grounding contacts of receptacles and cord connectors shall be grounded by connection to the equipment grounding conductor of the circuit supplying the receptacle or cord connector. The branch circuit wiring method shall include or provide an equipment grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected.
(iv) Replacement of receptacles shall comply with the following requirements:
(A) Where a grounding means exists in the receptacle enclosure or a grounding conductor is installed, grounding-type receptacles shall be used and shall be connected to the grounding means or conductor.
(B) Ground-fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this subpart.
(C) Where a grounding means does not exist in the receptacle enclosure, the installation shall comply with one of the following provisions:
(1) A nongrounding-type receptacle may be replaced with another nongrounding-type receptacle; or
(2) A nongrounding-type receptacle may be replaced with a ground-fault circuit-interrupter-type of receptacle that is marked "No Equipment Ground;" an equipment grounding conductor may not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle; or
(3) A nongrounding-type receptacle may be replaced with a grounding-type receptacle where supplied through a ground-fault circuit-interrupter; the replacement receptacle shall be marked "GFCI Protected" and "No Equipment Ground;" an equipment grounding conductor may not be connected to such grounding-type receptacles.
(v) Receptacles connected to circuits having different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.
(3) Identification of ungrounded conductors. Where more than one nominal voltage system exists in a building, each ungrounded system conductor shall be identified by phase and system. This means of identification shall be permanently posted at each branch-circuit panelboard.
(4) Ground-fault circuit interrupter protection for personnel. (i) All 125-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms or on rooftops shall have ground-fault circuit-interrupter protection for personnel.
(ii) The following requirements apply to temporary wiring installations that are used during maintenance, remodeling, or repair of buildings, structures, or equipment or during similar activities:
(A) All 125-volt, single-phase, 15- and 20- and 30-ampere receptacle outlets that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel. However, receptacles on a 2-wire, single-phase portable or vehicle-mounted generator rated not more than 5 kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, are permitted without ground-fault circuit-interrupter protection for personnel.
Note 1 to paragraph (b)(4)(ii)(A) of this section: A cord connector on an extension cord set is considered to be a receptacle outlet if the cord set is used for temporary electric power.
Note 2 to paragraph (b)(4)(ii)(A) of this section: Cord sets and devices incorporating listed ground-fault circuit-interrupter protection for personnel are acceptable forms of protection.
(B) Receptacles other than 125 volt, single-phase, 15-, 20-, and 30-ampere receptacles that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel.
(5) Outlet devices. Outlet devices shall have an ampere rating not less than the load to be served and shall comply with the following provisions:
(i) Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-duty lampholder shall have a rating of not less than 660 watts if of the admedium type and not less than 750 watts if of any other type.
(ii) Receptacle outlets shall comply with the following provisions:
(A) A single receptacle installed on an individual branch circuit shall have an ampere rating of not less than that of the branch circuit.
(B) Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle may not supply a total cord- and plug-connected load in excess of the maximum specified in Table S-4.
(C) Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table S-5; or, where larger than 50 amperes, the receptacle rating may not be less than the branch-circuit rating. However, receptacles of cord- and plug-connected arc welders may have ampere ratings not less than the minimum branch-circuit conductor ampacity.
(6) Cord connections. A receptacle outlet shall be installed wherever flexible cords with attachment plugs are used. Where flexible cords are permitted to be permanently connected, receptacles may be omitted.
Table S-4.--Maximum Cord- and Plug-Connected Load to Receptacle
Circuit rating (amperes) Receptacle rating (amperes) Maximum rating load (amperes)
15 or 20
Table S-5.--Receptacle Ratings for Various Size Circuits
Circuit rating (amperes) Receptacle rating (amperes)
50 Not over 15
(c) Outside conductors, 600 volts, nominal, or less. The following requirements apply to branch-circuit, feeder, and service conductors rated 600 volts, nominal, or less and run outdoors as open conductors.
(1) Conductors on poles. Conductors on poles shall have a separation of not less than 305 mm (1.0 ft) where not placed on racks or brackets. Conductors supported on poles shall provide a horizontal climbing space not less than the following:
(i) Power conductors below communication conductors -- 762 mm (30 in.);
(ii) Power conductors alone or above communication conductors:
300 volts or less -- 610 mm (24 in.),
Over 300 volts -- 762 mm (30 in.);
(iii) Communication conductors below power conductors -- same as power conductors;
(iv) Communications conductors alone -- no requirement.
(2) Clearance from ground. Open conductors, open multiconductor cables, and service-drop conductors of not over 600 volts, nominal, shall conform to the minimum clearances specified in Table S-6.
Table S-6.--Clearances From Ground
Distance Installations built before the effective date of the final rule Installations built on or after the effective date of the final rule
Maximum voltage Conditions Voltage to ground Conditions
3.05 m (10.0 ft) < 600 V Above finished grade or sidewalks, or from any platform or projection from which they might be reached. (If these areas are accessible to other than to other than pedestrian traffic, then one of the other conditions applies.) < 150 V Above finished grade or sidewalks, or any platform or projection from they might be reached. (If these areas are accessible to other than pedestrian traffic, then one of the other conditions applies.
3.66 m (12.0 ft) < 600 V Over areas, other than public streets, alleys, roads, and driveways, subject to vehicular traffic other than truck traffic. < 300 V Over residential property and driveways.
Over commercial areas subject to pedestrian trafficor to vehicular traffic other than truck traffic
(This category includes conditions covered under the 3.05-m (10.0-ft) category where the voltage exceeds 150 V.)
4.57 m (15.0 ft) < 600 V Over areas, other than public streets, alleys, roads, and driveways, subject to truck traffic. 301 to 600 V Over residential , property and driveways
Over commercial areas subject to pedestrian traffic or to vehicular traffic other than truck traffic.
5.49 m (18.0 ft) < 600 V Over public streets, alleys, roads, and driveways. < 600 V Over public streets, alleys, roads, and driveways.
Over commercial areas subject to truck traffic.
Other land traversed by vehicles, including land used for cultivating or grazing and forests and orchards.
(3) Clearance from building openings. (i) Service conductors installed as open conductors or multiconductor cable without an overall outer jacket shall have a clearance of not less than 914 mm (3.0 ft) from windows that are designed to be opened, doors, porches, balconies, ladders, stairs, fire escapes, and similar locations. However, conductors that run above the top level of a window may be less than 914 mm (3.0 ft) from the window. Vertical clearance of final spans above, or within 914 mm (3.0 ft) measured horizontally of, platforms, projections, or surfaces from which they might be reached shall be maintained in accordance with paragraph (c)(2) of this section.
(ii) Overhead service conductors may not be installed beneath openings through which materials may be moved, such as openings in farm and commercial buildings, and may not be installed where they will obstruct entrance to these building openings.
(4) Above roofs. Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2.44 m (8.0 ft) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 914 mm (3.0 ft) in all directions from the edge of the roof.
(i) The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of paragraph (c)(2) of this section.
(ii) A reduction in clearance to 914 mm (3.0 ft) is permitted where the voltage between conductors does not exceed 300 and the roof has a slope of 102 mm (4 in.) in 305 mm (12 in.) or greater.
(iii) A reduction in clearance above only the overhanging portion of the roof to not less than 457 mm (18 in.) is permitted where the voltage between conductors does not exceed 300 if (1) the conductors do not pass above the roof overhang for a distance of more than 1.83 m (6.0 ft), 1.22 m (4.0 ft) horizontally, and (2) the conductors are terminated at a through-the-roof raceway or approved support.
(iv) The requirement for maintaining a vertical clearance of 914 mm (3.0 ft) from the edge of the roof does not apply to the final conductor span where the conductors are attached to the side of a building.
(d) Location of outdoor lamps. Lamps for outdoor lighting shall be located below all energized conductors, transformers, or other electric equipment, unless such equipment is controlled by a disconnecting means that can be locked in the open position, or unless adequate clearances or other safeguards are provided for relamping operations.
(e) Services -- (1) Disconnecting means. (i) Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors. The service disconnecting means shall plainly indicate whether it is in the open or closed position and shall be installed at a readily accessible location nearest the point of entrance of the service-entrance conductors.
(ii) Each service disconnecting means shall simultaneously disconnect all ungrounded conductors.
(iii) Each service disconnecting means shall be suitable for the prevailing conditions.
(2) Services over 600 volts, nominal. The following additional requirements apply to services over 600 volts, nominal.
(i) Service-entrance conductors installed as open wires shall be guarded to make them accessible only to qualified persons.
(ii) Signs warning of high voltage shall be posted where unqualified employees might come in contact with live parts.
(f) Overcurrent protection -- (1) 600 volts, nominal, or less. The following requirements apply to overcurrent protection of circuits rated 600 volts, nominal, or less.
(i) Conductors and equipment shall be protected from overcurrent in accordance with their ability to safely conduct current.
(ii) Except for motor running overload protection, overcurrent devices may not interrupt the continuity of the grounded conductor unless all conductors of the circuit are opened simultaneously.
(iii) A disconnecting means shall be provided on the supply side of all fuses in circuits over 150 volts to ground and cartridge fuses in circuits of any voltage where accessible to other than qualified persons so that each individual circuit containing fuses can be independently disconnected from the source of power. However, a current-limiting device without a disconnecting means is permitted on the supply side of the service disconnecting means. In addition, a single disconnecting means is permitted on the supply side of more than one set of fuses as permitted by the exception to § 1910.305(j)(4)(vi), for group operation of motors and for fixed electric space-heating equipment.
(iv) Overcurrent devices shall be readily accessible to each employee or authorized building management personnel. These overcurrent devices may not be located where they will be exposed to physical damage or in the vicinity of easily ignitable material.
(v) Fuses and circuit breakers shall be so located or shielded that employees will not be burned or otherwise injured by their operation. Handles or levers of circuit breakers, and similar parts that may move suddenly in such a way that persons in the vicinity are likely to be injured by being struck by them, shall be guarded or isolated.
(vi) Circuit breakers shall clearly indicate whether they are in the open (off) or closed (on) position.
(vii) Where circuit breaker handles on switchboards are operated vertically rather than horizontally or rotationally, the up position of the handle shall be the closed (on) position.
(viii) Circuit breakers used as switches in 120-volt and 277-volt, fluorescent lighting circuits shall be listed and marked "SWD."
(ix) A circuit breaker with a straight voltage rating, such as 240 V or 480 V, may only be installed in a circuit in which the nominal voltage between any two conductors does not exceed the circuit breaker's voltage rating. A two-pole circuit breaker may not be used for protecting a 3-phase, corner-grounded delta circuit unless the circuit breaker is marked 1[phis]-3[phis] to indicate such suitability. A circuit breaker with a slash rating, such as 120/240 V or 480Y/277 V, may only be installed in a circuit where the nominal voltage of any conductor to ground does not exceed the lower of the two values of the circuit breaker's voltage rating and the nominal voltage between any two conductors does not exceed the higher value of the circuit breaker's voltage rating.
(2) Feeders and branch circuits over 600 volts, nominal. The following requirements apply to feeders and branch circuits energized at more than 600 volts, nominal:
(i) Feeder and branch-circuit conductors shall have overcurrent protection in each ungrounded conductor located at the point where the conductor receives its supply or at a location in the circuit determined under engineering supervision.
(A) Circuit breakers used for overcurrent protection of three-phase circuits shall have a minimum of three overcurrent relays operated from three current transformers. On three-phase, three-wire circuits, an overcurrent relay in the residual circuit of the current transformers may replace one of the phase relays. An overcurrent relay, operated from a current transformer that links all phases of a three-phase, three-wire circuit, may replace the residual relay and one other phase-current transformers. Where the neutral is not grounded on the load side of the circuit, the current transformer may link all three phase conductors and the grounded circuit conductor (neutral).
(B) If fuses are used for overcurrent protection, a fuse shall be connected in series with each ungrounded conductor.
(ii) Each protective device shall be capable of detecting and interrupting all values of current that can occur at its location in excess of its trip setting or melting point.
(iii) The operating time of the protective device, the available short-circuit current, and the conductor used shall be coordinated to prevent damaging or dangerous temperatures in conductors or conductor insulation under short-circuit conditions.
(iv) The following additional requirements apply to feeders only:
(A) The continuous ampere rating of a fuse may not exceed three times the ampacity of the conductors. The long-time trip element setting of a breaker or the minimum trip setting of an electronically actuated fuse may not exceed six times the ampacity of the conductor.
For fire pumps, conductors may be protected for short circuit only.
(B) Conductors tapped to a feeder may be protected by the feeder overcurrent device where that overcurrent device also protects the tap conductor.
(g) Grounding. Paragraphs (g)(1) through (g)(8) of this section contain grounding requirements for systems, circuits, and equipment.
(1) Systems to be grounded. Systems that supply premises wiring shall be grounded as follows:
(i) All 3-wire dc systems shall have their neutral conductor grounded.
(ii) Two-wire dc systems operating at over 50 volts through 300 volts between conductors shall be grounded unless:
(A) They supply only industrial equipment in limited areas and are equipped with a ground detector; or
(B) They are rectifier-derived from an ac system complying with paragraphs (g)(1)(iii), (g)(1)(iv), and (g)(1)(v) of this section; or
(C) They are fire-alarm circuits having a maximum current of 0.030 amperes.
(iii) AC circuits of less than 50 volts shall be grounded if they are installed as overhead conductors outside of buildings or if they are supplied by transformers and the transformer primary supply system is ungrounded or exceeds 150 volts to ground.
(iv) AC systems of 50 volts to 1000 volts shall be grounded under any of the following conditions, unless exempted by paragraph (g)(1)(v) of this section:
(A) If the system can be so grounded that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts;
(B) If the system is nominally rated three-phase, four-wire wye connected in which the neutral is used as a circuit conductor;
(C) If the system is nominally rated three-phase, four-wire delta connected in which the midpoint of one phase is used as a circuit conductor; or
(D) If a service conductor is uninsulated.
(v) AC systems of 50 volts to 1000 volts are not required to be grounded under any of the following conditions:
(A) If the system is used exclusively to supply industrial electric furnaces for melting, refining, tempering, and the like;
(B) If the system is separately derived and is used exclusively for rectifiers supplying only adjustable speed industrial drives;
(C) If the system is separately derived and is supplied by a transformer that has a primary voltage rating less than 1000 volts, provided all of the following conditions are met:
(1) The system is used exclusively for control circuits,
(2) The conditions of maintenance and supervision ensure that only qualified persons will service the installation,
(3) Continuity of control power is required, and
(4) Ground detectors are installed on the control system;
(D) If the system is an isolated power system that supplies circuits in health care facilities; or
(E) If the system is a high-impedance grounded neutral system in which a grounding impedance, usually a resistor, limits the ground-fault current to a low value for 3-phase ac systems of 480 volts to 1000 volts provided all of the following conditions are met:
(2) Continuity of power is required,
(3) Ground detectors are installed on the system, and
(4) Line-to-neutral loads are not served.
(2) Portable and vehicle-mounted generators. (i) The frame of a portable generator need not be grounded and may serve as the grounding electrode for a system supplied by the generator under the following conditions:
(A) The generator supplies only equipment mounted on the generator or cord- and plug-connected equipment through receptacles mounted on the generator, or both; and
(B) The noncurrent-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.
(ii) The frame of a vehicle need not be grounded and may serve as the grounding electrode for a system supplied by a generator located on the vehicle under the following conditions:
(A) The frame of the generator is bonded to the vehicle frame; and
(B) The generator supplies only equipment located on the vehicle and cord- and plug-connected equipment through receptacles mounted on the vehicle; and
(C) The noncurrent-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame; and
(D) The system complies with all other provisions of paragraph (g) of this section.
(iii) A neutral conductor shall be bonded to the generator frame where the generator is a component of a separately derived system.
(3) Grounding connections. (i) For a grounded system, a grounding electrode conductor shall be used to connect both the equipment grounding conductor and the grounded circuit conductor to the grounding electrode. Both the equipment grounding conductor and the grounding electrode conductor shall be connected to the grounded circuit conductor on the supply side of the service disconnecting means or on the supply side of the system disconnecting means or overcurrent devices if the system is separately derived.
(ii) For an ungrounded service-supplied system, the equipment grounding conductor shall be connected to the grounding electrode conductor at the service equipment. For an ungrounded separately derived system, the equipment grounding conductor shall be connected to the grounding electrode conductor at, or ahead of, the system disconnecting means or overcurrent devices.
(iii) On extensions of existing branch circuits that do not have an equipment grounding conductor, grounding-type receptacles may be grounded to a grounded cold water pipe near the equipment.
(4) Grounding path. The path to ground from circuits, equipment, and enclosures shall be permanent and continuous.
(5) Supports, enclosures, and equipment to be grounded. (i) Metal cable trays, metal raceways, and metal enclosures for conductors shall be grounded, except that:
(A) Metal enclosures such as sleeves that are used to protect cable assemblies from physical damage need not be grounded; and
(B) Metal enclosures for conductors added to existing installations of open wire, knob-and-tube wiring, and nonmetallic-sheathed cable need not be grounded if all of the following conditions are met:
(1) Runs are less than 7.62 meters (25.0 ft);
(2) Enclosures are free from probable contact with ground, grounded metal, metal laths, or other conductive materials; and
(3) Enclosures are guarded against employee contact.
(ii) Metal enclosures for service equipment shall be grounded.
(iii) Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and metal outlet or junction boxes that are part of the circuit for these appliances shall be grounded.
(iv) Exposed noncurrent-carrying metal parts of fixed equipment that may become energized shall be grounded under any of the following conditions:
(A) If within 2.44 m (8 ft) vertically or 1.52 m (5 ft) horizontally of ground or grounded metal objects and subject to employee contact;
(B) If located in a wet or damp location and not isolated;
(C) If in electrical contact with metal;
(D) If in a hazardous (classified) location;
(E) If supplied by a metal-clad, metal-sheathed, or grounded metal raceway wiring method; or
(F) If equipment operates with any terminal at over 150 volts to ground.
(v) Notwithstanding the provisions of paragraph (g)(5)(iv) of this section, exposed noncurrent-carrying metal parts of the following types of fixed equipment need not be grounded:
(A) Enclosures for switches or circuit breakers used for other than service equipment and accessible to qualified persons only;
(B) Electrically heated appliances that are permanently and effectively insulated from ground;
(C) Distribution apparatus, such as transformer and capacitor cases, mounted on wooden poles, at a height exceeding 2.44 m (8.0 ft) above ground or grade level; and
(D) Listed equipment protected by a system of double insulation, or its equivalent, and distinctively marked as such.
(vi) Exposed noncurrent-carrying metal parts of cord- and plug-connected equipment that may become energized shall be grounded under any of the following conditions:
(A) If in hazardous (classified) locations (see § 1910.307);
(B) If operated at over 150 volts to ground, except for guarded motors and metal frames of electrically heated appliances if the appliance frames are permanently and effectively insulated from ground;
(C) If the equipment is of the following types:
(1) Refrigerators, freezers, and air conditioners;
(2) Clothes-washing, clothes-drying and dishwashing machines, sump pumps, and electric aquarium equipment;
(3) Hand-held motor-operated tools, stationary and fixed motor-operated tools, and light industrial motor-operated tools;
(4) Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers;
(5) Cord- and plug-connected appliances used in damp or wet locations, or by employees standing on the ground or on metal floors or working inside of metal tanks or boilers;
(6) Portable and mobile X-ray and associated equipment;
(7) Tools likely to be used in wet and conductive locations; and
(8) Portable hand lamps.
(vii) Notwithstanding the provisions of paragraph (g)(5)(vi) of this section, the following equipment need not be grounded:
(A) Tools likely to be used in wet and conductive locations if supplied through an isolating transformer with an ungrounded secondary of not over 50 volts, and
(B) Listed or labeled portable tools and appliances if protected by an approved system of double insulation, or its equivalent, and distinctively marked.
(6) Nonelectrical equipment. The metal parts of the following nonelectrical equipment shall be grounded: Frames and tracks of electrically operated cranes and hoists; frames of nonelectrically driven elevator cars to which electric conductors are attached; hand-operated metal shifting ropes or cables of electric elevators; and metal partitions, grill work, and similar metal enclosures around equipment of over 750 volts between conductors.
(7) Methods of grounding fixed equipment. (i) Noncurrent-carrying metal parts of fixed equipment, if required to be grounded by this subpart, shall be grounded by an equipment grounding conductor that is contained within the same raceway, cable, or cord, or runs with or encloses the circuit conductors. For dc circuits only, the equipment grounding conductor may be run separately from the circuit conductors.
(ii) Electric equipment is considered to be effectively grounded if it is secured to, and in electrical contact with, a metal rack or structure that is provided for its support and the metal rack or structure is grounded by the method specified for the noncurrent-carrying metal parts of fixed equipment in paragraph (g)(7)(i) of this section. Metal car frames supported by metal hoisting cables attached to or running over metal sheaves or drums of grounded elevator machines are also considered to be effectively grounded. For installations made before April 16, 1981, only, electric equipment is also considered to be effectively grounded if it is secured to, and in metallic contact with, the grounded structural metal frame of a building.
(8) Grounding of systems and circuits of 1000 volts and over (high voltage). If high voltage systems are grounded, they shall comply with all applicable provisions of paragraphs (g)(1) through (g)(7) of this section as supplemented and modified by the following requirements:
(i) Systems supplying portable or mobile high voltage equipment, other than substations installed on a temporary basis, shall comply with the following:
(A) The system shall have its neutral grounded through an impedance. If a delta-connected high voltage system is used to supply the equipment, a system neutral shall be derived.
(B) Exposed noncurrent-carrying metal parts of portable and mobile equipment shall be connected by an equipment grounding conductor to the point at which the system neutral impedance is grounded.
(C) Ground-fault detection and relaying shall be provided to automatically deenergize any high voltage system component that has developed a ground fault. The continuity of the equipment grouding conductor shall be continuously monitored so as to deenergize automatically the high voltage feeder to the portable equipment upon loss of continuity of the equipment grounding conductor.
(D) The grounding electrode to which the portable equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 6.1 m (20.0 ft) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, such as buried pipe, fence, and so forth.
(ii) All noncurrent-carrying metal parts of portable equipment and fixed equipment, including their associated fences, housings, enclosures, and supporting structures, shall be grounded. However, equipment that is guarded by location and isolated from ground need not be grounded. Additionally, pole-mounted distribution apparatus at a height exceeding 2.44 m (8.0 ft) above ground or grade level need not be grounded.
(a) Wiring methods. The provisions of this section do not apply to conductors that are an integral part of factory-assembled equipment.
(1) General requirements. (i) Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal noncurrent-carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be effectively bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them. Any nonconductive paint, enamel, or similar coating shall be removed at threads, contact points, and contact surfaces or be connected by means of fittings designed so as to make such removal unnecessary.
(ii) Where necessary for the reduction of electrical noise (electromagnetic interference) of the grounding circuit, an equipment enclosure supplied by a branch circuit may be isolated from a raceway containing circuits supplying only that equipment by one or more listed nonmetallic raceway fittings located at the point of attachment of the raceway to the equipment enclosure. The metal raceway shall be supplemented by an internal insulated equipment grounding conductor installed to ground the equipment enclosure.
(iii) No wiring systems of any type may be installed in ducts used to transport dust, loose stock, or flammable vapors. No wiring system of any type may be installed in any duct used for vapor removal or for ventilation of commercial-type cooking equipment, or in any shaft containing only such ducts.
(2) Temporary wiring. Except as specifically modified in this paragraph, all other requirements of this subpart for permanent wiring shall also apply to temporary wiring installations.
(i) Temporary electrical power and lighting installations of 600 volts, nominal, or less may be used only as follows:
(A) During and for remodeling, maintenance, or repair of buildings,structures, or equipment, and similar activities;
(B) For a period not to exceed 90 days for Christmas decorative lighting, carnivals, and similar purposes; or
(C) For experimental or development work, and during emergencies.
(ii) Temporary wiring shall be removed immediately upon completion of the project or purpose for which the wiring was installed.
(iii) Temporary electrical installations of more than 600 volts may be used only during periods of tests, experiments, or emergencies.
(iv) The following requirements apply to feeders:
(A) Feeders shall originate in an approved distribution center.
(B) Conductors shall be run as multiconductor cord or cable assemblies. However, if installed as permitted in paragraph (a)(2)(i)(C) of this section, and if accessible only to qualified persons, feeders may be run as single insulated conductors.
(v) The following requirements apply to branch circuits:
(A) Branch circuits shall originate in an approved power outlet or panelboard.
(B) Conductors shall be multiconductor cord or cable assemblies or open conductors. If run as open conductors they shall be fastened at ceiling height every 3.05 m (10.0 ft).
(C) No branch-circuit conductor may be laid on the floor.
(D) Each branch circuit that supplies receptacles or fixed equipment shall contain a separate equipment grounding conductor if run as open conductors.
(vi) Receptacles shall be of the grounding type. Unless installed in a continuous grounded metallic raceway or metallic covered cable, each branch circuit shall contain a separate equipment grounding conductor and all receptacles shall be electrically connected to the grounding conductor.
(vii) No bare conductors nor earth returns may be used for the wiring of any temporary circuit.
(viii) Suitable disconnecting switches or plug connectors shall be installed to permit the disconnection of all ungrounded conductors of each temporary circuit. Multiwire branch circuits shall be provided with a means to disconnect simultaneously all ungrounded conductors at the power outlet or panelboard where the branch circuit originated.
Note to paragraph (a)(2)(viii) of this section. Circuit breakers with their handles connected by approved handle ties are considered a single disconnecting means for the purpose of this requirement.
(ix) All lamps for general illumination shall be protected from accidental contact or breakage by a suitable fixture or lampholder with a guard. Brass shell, paper-lined sockets, or other metal-cased sockets may not be used unless the shell is grounded.
(x) Flexible cords and cables shall be protected from accidental damage, as might be caused, for example, by sharp corners, projections, and doorways or other pinch points.
(xi) Cable assemblies and flexible cords and cables shall be supported in place at intervals that ensure that they will be protected from physical damage. Support shall be in the form of staples, cables ties, straps, or similar type fittings installed so as not to cause damage.
(3) Cable trays. (i) Only the following wiring methods may be installed in cable tray systems: Armored cable, electrical metallic tubing, electrical nonmetallic tubing, fire alarm cables, flexible metal conduit, flexible metallic tubing, instrumentation tray cable, intermediate metal conduit, liquidtight flexible metal conduit and liquidtight flexible nonmetallic conduit, metal-clad cable, mineral-insulated, metal-sheathed cable, multiconductor service-entrance cable, multiconductor underground feeder and branch-circuit cable, multipurpose and communications cables, nonmetallic-sheathed cable, power and control tray cable, power-limited tray cable, optical fiber cables, other factory-assembled, multiconductor control, signal, or power cables that are specifically approved for installation in cable trays, rigid metal conduit, and rigid nonmetallic conduit.
(ii) In industrial establishments where conditions of maintenance and supervision assure that only qualified persons will service the installed cable tray system, the following cables may also be installed in ladder, ventilated-trough, or ventilated-channel cable trays:
(A) Single conductor cable; the cable shall be No. 1/0 or larger and shall be of a type listed and marked on the surface for use in cable trays; where Nos. 1/0 through 4/0 single conductor cables are installed in ladder cable tray, the maximum allowable rung spacing for the ladder cable tray shall be 229 mm (9 in.); where exposed to direct rays of the sun, cables shall be identified as being sunlight resistant;
(B) Welding cables installed in dedicated cable trays;
(C) Single conductors used as equipment grounding conductors; these conductors, which may be insulated, covered, or bare, shall be No. 4 or larger;
(D) Multiconductor cable, Type MV; where exposed to direct rays of the sun, the cable shall be identified as being sunlight resistant.
(iii) Metallic cable trays may be used as equipment grounding conductors only where continuous maintenance and supervision ensure that qualified persons will service the installed cable tray system.
(iv) Cable trays in hazardous (classified) locations may contain only the cable types permitted in such locations. (See § 1910.307.)
(v) Nonmetallic cable trays may only be installed in corrosive areas and in areas requiring voltage isolation.
(vi) Cable tray systems may not be used in hoistways or where subjected to severe physical damage.
(4) Open wiring on insulators. (i) Open wiring on insulators is only permitted on systems of 600 volts, nominal, or less for industrial or agricultural establishments, indoors or outdoors, in wet or dry locations, where subject to corrosive vapors, and for services.
(ii) Conductors smaller than No. 8 shall be rigidly supported on noncombustible, nonabsorbent insulating materials and may not contact any other objects. Supports shall be installed as follows:
(A) Within 152 mm (6 in.) from a tap or splice;
(B) Within 305 mm (12 in.) of a dead-end connection to a lampholder or receptacle; and
(C) At intervals not exceeding 1.37 m (4.5 ft), and at closer intervals sufficient to provide adequate support where likely to be disturbed.
(iii) In dry locations, where not exposed to severe physical damage, conductors may be separately enclosed in flexible nonmetallic tubing. The tubing shall be in continuous lengths not exceeding 4.57 m (15.0 ft) and secured to the surface by straps at intervals not exceeding 1.37 m (4.5 ft).
(iv) Open conductors shall be separated from contact with walls, floors, wood cross members, or partitions through which they pass by tubes or bushings of noncombustible, nonabsorbent insulating material. If the bushing is shorter than the hole, a waterproof sleeve of nonconductive material shall be inserted in the hole and an insulating bushing slipped into the sleeve at each end in such a manner as to keep the conductors absolutely out of contact with the sleeve. Each conductor shall be carried through a separate tube or sleeve.
(v) Where open conductors cross ceiling joints and wall studs and are exposed to physical damage (for example, located within 2.13 m (7.0 ft) of the floor), they shall be protected.
(b) Cabinets, boxes, and fittings -- (1) Conductors entering boxes, cabinets, or fittings. (i) Conductors entering cutout boxes, cabinets, or fittings shall be protected from abrasion, and openings through which conductors enter shall be effectively closed.
(ii) Unused openings in cabinets, boxes, and fittings shall be effectively closed.
(iii) Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure. However, where cable with an entirely nonmetallic sheath enters the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 457 mm (18 in.) or more than 3.05 m (10.0 ft) in length, the cable need not be secured to the cabinet, box, or enclosure provided all of the following conditions are met:
(A) Each cable is fastened within 305 mm (12 in.) of the outer end of the raceway, measured along the sheath;
(B) The raceway extends directly above the enclosure and does not penetrate a structural ceiling;
(C) A fitting is provided on each end of the raceway to protect the cable from abrasion, and the fittings remain accessible after installation;
(D) The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway;
(E) The cable sheath is continuous through the raceway and extends into the enclosure not less than 6.35 mm (0.25 in.) beyond the fitting;
(F) The raceway is fastened at its outer end and at other points as necessary; and
(G) Where installed as conduit or tubing, the allowable cable fill does not exceed that permitted for complete conduit or tubing systems.
(2) Covers and canopies. (i) All pull boxes, junction boxes, and fittings shall be provided with covers identified for the purpose. If metal covers are used they shall be grounded. In completed installations each outlet box shall have a cover, faceplate, or fixture canopy. Covers of outlet boxes having holes through which flexible cord pendants pass shall be provided with bushings designed for the purpose or shall have smooth, well-rounded surfaces on which the cords may bear.
(ii) Where a fixture canopy or pan is used, any combustible wall or ceiling finish exposed between the edge of the canopy or pan and the outlet box shall be covered with noncombustible material.
(3) Pull and junction boxes for systems over 600 volts, nominal. In addition to other requirements in this section, the following requirements apply to pull and junction boxes for systems over 600 volts, nominal:
(i) Boxes shall provide a complete enclosure for the contained conductors or cables.
(ii) Boxes shall be closed by suitable covers securely fastened in place.
Note to paragraph (b)(3)(ii) of this section: Underground box covers that weigh over 45.4 kg (100 lbs) meet this requirement.
(iii) Covers for boxes shall be permanently marked "HIGH VOLTAGE." The marking shall be on the outside of the box cover and shall be readily visible and legible.
(c) Switches -- (1) Single-throw knife switches. Single-throw knife switches shall be so placed that gravity will not tend to close them. Single-throw knife switches approved for use in the inverted position shall be provided with a locking device that will ensure that the blades remain in the open position when so set.
(2) Double-throw knife switches. Double-throw knife switches may be mounted so that the throw will be either vertical or horizontal. However, if the throw is vertical, a locking device shall be provided to ensure that the blades remain in the open position when so set.
(3) Connection of switches. (i) Single-throw knife switches and switches with butt contacts shall be connected so that the blades are deenergized when the switch is in the open position.
(ii) Single-throw knife switches, molded-case switches, switches with butt contacts, and circuit breakers used as switches shall be connected so that the terminals supplying the load are deenergized when the switch is in the open position. However, blades and terminals supplying the load of a switch may be energized when the switch is in the open position where the switch is connected to circuits or equipment inherently capable of providing a backfeed source of power. For such installations, a permanent sign shall be installed on the switch enclosure or immediately adjacent to open switches that reads, "WARNING -- LOAD SIDE TERMINALS MAY BE ENERGIZED BY BACKFEED."
(4) Faceplates for flush-mounted snap switches. Snap switches mounted in boxes shall have faceplates installed so as to completely cover the opening and seat against the finished surface.
(5) Grounding. Snap switches, including dimmer switches, shall be effectively grounded and shall provide a means to ground metal faceplates, whether or not a metal faceplate is installed. However, if no grounding means exists within the snap-switch enclosure, or where the wiring method does not include or provide an equipment ground, a snap switch without a grounding connection is permitted for replacement purposes only. Such snap switches shall be provided with a faceplate of nonconducting, noncombustible material if they are located within reach of conducting floors or other conducting surfaces.
(d) Switchboards and panelboards -- (1) Switchboards with exposed live parts. Switchboards that have any exposed live parts shall be located in permanently dry locations and shall be accessible only to qualified persons.
(2) Panelboard enclosures. Panelboards shall be mounted in cabinets, cutout boxes, or enclosures designed for the purpose and shall be dead front. However, panelboards other than the dead front externally-operable type are permitted where accessible only to qualified persons.
(3) Knife switches mounted in switchboards or panelboards. Exposed blades of knife switches mounted in switchboards or panelboards shall be dead when open.
(e) Enclosures for damp or wet locations -- (1) Cabinets, cutout boxes, fittings, boxes, and panelboard enclosures. Cabinets, cutout boxes, fittings, boxes, and panelboard enclosures in damp or wet locations shall be installed so as to prevent moisture or water from entering and accumulating within the enclosures and shall be mounted so there is at least 6.35-mm (0.25-in.) airspace between the enclosure and the wall or other supporting surface. However, nonmetallic enclosures may be installed without the airspace on a concrete, masonry, tile, or similar surface. The enclosures shall be weatherproof in wet locations.
(2) Switches, circuit breakers, and switchboards. Switches, circuit breakers, and switchboards installed in wet locations shall be enclosed in weatherproof enclosures.
(f) Conductors for general wiring -- (1) Insulation. All conductors used for general wiring shall be insulated unless otherwise permitted in this subpart.
(2) Type. The conductor insulation shall be of a type that is approved for the voltage, operating temperature, and location of use.
(3) Distinguishable. Insulated conductors shall be distinguishable by appropriate color or other suitable means as being grounded conductors, ungrounded conductors, or equipment grounding conductors.
(g) Flexible cords and cables -- (1) Use of flexible cords and cables. (i) Flexible cords and cables shall be approved for conditions of use and location.
(ii) Flexible cords and cables may be used only for:
(A) Pendants;
(B) Wiring of fixtures;
(C) Connection of portable lamps or appliances;
(D) Portable and mobile signs;
(E) Elevator cables;
(F) Wiring of cranes and hoists;
(G) Connection of stationary equipment to facilitate their frequent interchange;
(H) Prevention of the transmission of noise or vibration;
(I) Appliances where the fastening means and mechanical connections are designed to permit removal for maintenance and repair;
(J) Data processing cables approved as a part of the data processing system;
(K) Connection of moving parts; and
(L) Temporary wiring as permitted in paragraph (a)(2) of this section.
(iii) If used as permitted in paragraphs (g)(1)(ii)(C), (g)(1)(ii)(G), or (g)(1)(ii)(I) of this section, the flexible cord shall be equipped with an attachment plug and shall be energized from an approved receptacle outlet.
(iv) Unless specifically permitted otherwise in paragraph
(g)(1)(ii) of this section, flexible cords and cables may not be used:
(A) As a substitute for the fixed wiring of a structure;
(B) Where run through holes in walls, ceilings, or floors;
(C) Where run through doorways, windows, or similar openings;
(D) Where attached to building surfaces;
(E) Where concealed behind building walls, ceilings, or floors; or
(F) Where installed in raceways, except as otherwise permitted in this subpart.
(v) Flexible cords used in show windows and showcases shall be Type S, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO, SJO, SJOO, SJT, SJTO, SJTOO, SO, SOO, ST, STO, or STOO except for the wiring of chain-supported lighting fixtures and supply cords for portable lamps and other merchandise being displayed or exhibited.
(2) Identification, splices, and terminations. (i) A conductor of a flexible cord or cable that is used as a grounded conductor or an equipment grounding conductor shall be distinguishable from other conductors. Types S, SC, SCE, SCT, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO, SJO, SJT, SJTO, SJTOO, SO, SOO, ST, STO, and STOO flexible cords and Types G, G-GC, PPE, and W flexible cables shall be durably marked on the surface at intervals not exceeding 610 mm (24 in.) with the type designation, size, and number of conductors.
(ii) Flexible cords may be used only in continuous lengths without splice or tap. Hard-service cord and junior hard-service cord No. 14 and larger may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced.
(iii) Flexible cords and cables shall be connected to devices and fittings so that strain relief is provided that will prevent pull from being directly transmitted to joints or terminal screws.
(h) Portable cables over 600 volts, nominal. The following requirements apply to portable cables used at more than 600 volts, nominal:
(1) Conductor construction. Multiconductor portable cable for use in supplying power to portable or mobile equipment at over 600 volts, nominal, shall consist of No. 8 or larger conductors employing flexible stranding. However, the minimum size of the insulated ground-check conductor of Type G-GC cables shall be No. 10.
(2) Shielding. Cables operated at over 2,000 volts shall be shielded for the purpose of confining the voltage stresses to the insulation.
(3) Equipment grounding conductors. Grounding conductors shall be provided.
(4) Grounding shields. All shields shall be grounded.
(5) Minimum bending radii. The minimum bending radii for portable cables during installation and handling in service shall be adequate to prevent damage to the cable.
(6) Fittings. Connectors used to connect lengths of cable in a run shall be of a type that lock firmly together. Provisions shall be made to prevent opening or closing these connectors while energized. Strain relief shall be provided at connections and terminations.
(7) Splices. Portable cables may not be operated with splices unless the splices are of the permanent molded, vulcanized, or other approved type.
(8) Terminations. Termination enclosures shall be suitably marked with a high voltage hazard warning, and terminations shall be accessible only to authorized and qualified employees.
(i) Fixture wires -- (1) General. Fixture wires shall be approved for the voltage, temperature, and location of use. A fixture wire which is used as a grounded conductor shall be identified.
(2) Uses permitted. Fixture wires may be used only:
(i) For installation in lighting fixtures and in similar equipment where enclosed or protected and not subject to bending or twisting in use; or
(ii) For connecting lighting fixtures to the branch-circuit conductors supplying the fixtures.
(3) Uses not permitted. Fixture wires may not be used as branch-circuit conductors except as permitted for Class 1 power limited circuits and for fire alarm circuits.
(j) Equipment for general use -- (1) Lighting fixtures, lampholders, lamps, and receptacles. (i) Fixtures, lampholders, lamps, rosettes, and receptacles may have no live parts normally exposed to employee contact. However, rosettes and cleat-type lampholders and receptacles located at least 2.44 m (8.0 ft) above the floor may have exposed terminals.
(ii) Handlamps of the portable type supplied through flexible cords shall be equipped with a handle of molded composition or other material identified for the purpose, and a substantial guard shall be attached to the lampholder or the handle. Metal shell, paper-lined lampholders may not be used.
(iii) Lampholders of the screw-shell type shall be installed for use as lampholders only. Where supplied by a circuit having a grounded conductor, the grounded conductor shall be connected to the screw shell. Lampholders installed in wet or damp locations shall be of the weatherproof type.
(iv) Fixtures installed in wet or damp locations shall be identified for the purpose and shall be so constructed or installed that water cannot enter or accumulate in wireways, lampholders, or other electrical parts.
(2) Receptacles, cord connectors, and attachment plugs (caps). (i) All 15- and 20-ampere attachment plugs and connectors shall be constructed so that there are no exposed current-carrying parts except the prongs, blades, or pins. The cover for wire terminations shall be a part that is essential for the operation of an attachment plug or connector (dead-front construction). Attachment plugs shall be installed so that their prongs, blades, or pins are not energized unless inserted into an energized receptacle. No receptacles may be installed so as to require an energized attachment plug as its source of supply.
(ii) Receptacles, cord connectors, and attachment plugs shall be constructed so that no receptacle or cord connector will accept an attachment plug with a different voltage or current rating than that for which the device is intended. However, a 20-ampere T-slot receptacle or cord connector may accept a 15-ampere attachment plug of the same voltage rating.
(iii) Nongrounding-type receptacles and connectors may not be used for grounding-type attachment plugs.
(iv) A receptacle installed in a wet or damp location shall be suitable for the location.
(v) A receptacle installed outdoors in a location protected from the weather or in other damp locations shall have an enclosure for the receptacle that is weatherproof when the receptacle is covered (attachment plug cap not inserted and receptacle covers closed).
Note to paragraph (j)(2)(v) of this section. A receptacle is considered to be in a location protected from the weather when it is located under roofed open porches, canopies, marquees, or the like and where it will not be subjected to a beating rain or water runoff.
(vi) A receptacle installed in a wet location where the product intended to be plugged into it is not attended while in use (for example, sprinkler system controllers, landscape lighting, and holiday lights) shall have an enclosure that is weatherproof with the attachment plug cap inserted or removed.
(vii) A receptacle installed in a wet location where the product intended to be plugged into it will be attended while in use (for example, portable tools) shall have an enclosure that is weatherproof when the attachment plug cap is removed.
(3) Appliances. (i) Appliances may have no live parts normally exposed to contact other than parts functioning as open-resistance heating elements, such as the heating elements of a toaster, which are necessarily exposed.
(ii) Each appliance shall have a means to disconnect it from all ungrounded conductors. If an appliance is supplied by more than one source, the disconnecting means shall be grouped and identified.
(iii) Each electric appliance shall be provided with a nameplate giving the identifying name and the rating in volts and amperes, or in volts and watts. If the appliance is to be used on a specific frequency or frequencies, it shall be so marked. Where motor overload protection external to the appliance is required, the appliance shall be so marked.
(iv) Marking shall be located so as to be visible or easily accessible after installation.
(4) Motors. This paragraph applies to motors, motor circuits, and controllers.
(i) If specified in paragraph (j)(4) of this section that one piece of equipment shall be "within sight of" another piece of equipment, the piece of equipment shall be visible and not more than 15.24 m (50.0 ft) from the other.
(ii) An individual disconnecting means shall be provided for each controller. A disconnecting means shall be located within sight of the controller location. However, a single disconnecting means may be located adjacent to a group of coordinated controllers mounted adjacent to each other on a multi-motor continuous process machine. The controller disconnecting means for motor branch circuits over 600 volts, nominal, may be out of sight of the controller, if the controller is marked with a warning label giving the location and identification of the disconnecting means that is to be locked in the open position.
(iii) The disconnecting means shall disconnect the motor and the controller from all ungrounded supply conductors and shall be so designed that no pole can be operated independently.
(iv) The disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.
(v) The disconnecting means shall be readily accessible. If more than one disconnect is provided for the same equipment, only one need be readily accessible.
(vi) An individual disconnecting means shall be provided for each motor, but a single disconnecting means may be used for a group of motors under any one of the following conditions:
(A) If a number of motors drive several parts of a single machine or piece of apparatus, such as a metal or woodworking machine, crane, or hoist;
(B) If a group of motors is under the protection of one set of branch-circuit protective devices; or
(C) If a group of motors is in a single room within sight of the location of the disconnecting means.
(vii) Motors, motor-control apparatus, and motor branch-circuit conductors shall be protected against overheating due to motor overloads or failure to start, and against short-circuits or ground faults. These provisions do not require overload protection that will stop a motor where a shutdown is likely to introduce additional or increased hazards, as in the case of fire pumps, or where continued operation of a motor is necessary for a safe shutdown of equipment or process and motor overload sensing devices are connected to a supervised alarm.
(viii) Where live parts of motors or controllers operating at over 150 volts to ground are guarded against accidental contact only by location, and where adjustment or other attendance may be necessary during the operation of the apparatus, suitable insulating mats or platforms shall be provided so that the attendant cannot readily touch live parts unless standing on the mats or platforms.
(5) Transformers. (i) Paragraph (j)(5) of this section covers the installation of all transformers except the following:
(A) Current transformers;
(B) Dry-type transformers installed as a component part of other apparatus;
(C) Transformers that are an integral part of an X-ray, high frequency, or electrostatic-coating apparatus;
(D) Transformers used with Class 2 and Class 3 circuits, sign and outline lighting, electric discharge lighting, and power-limited fire- alarm circuits; and
(E) Liquid-filled or dry-type transformers used for research, development, or testing, where effective safeguard arrangements are provided.
(ii) The operating voltage of exposed live parts of transformer installations shall be indicated by signs or visible markings on the equipment or structure.
(iii) Dry-type, high fire point liquid-insulated, and askarel-insulated transformers installed indoors and rated over 35kV shall be in a vault.
(iv) Oil-insulated transformers installed indoors shall be installed in a vault.
(v) Combustible material, combustible buildings and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires that may originate in oil-insulated transformers attached to or adjacent to a building or combustible material.
(vi) Transformer vaults shall be constructed so as to contain fire and combustible liquids within the vault and to prevent unauthorized access. Locks and latches shall be so arranged that a vault door can be readily opened from the inside.
(vii) Any pipe or duct system foreign to the electrical installation may not enter or pass through a transformer vault.
Note to paragraph (j)(5)(vii) of this section. Piping or other facilities provided for vault fire protection, or for transformer cooling, are not considered foreign to the electrical installation.
(viii) Material may not be stored in transformer vaults.
(6) Capacitors. (i) All capacitors, except surge capacitors or capacitors included as a component part of other apparatus, shall be provided with an automatic means of draining the stored charge after the capacitor is disconnected from its source of supply.
(ii) The following requirements apply to capacitors installed on circuits operating at more than 600 volts, nominal:
(A) Group-operated switches shall be used for capacitor switching and shall be capable of the following:
(1) Carrying continuously not less than 135 percent of the rated current of the capacitor installation;
(2) Interrupting the maximum continuous load current of each capacitor, capacitor bank, or capacitor installation that will be switched as a unit;
(3) Withstanding the maximum inrush current, including contributions from adjacent capacitor installations; and
(4) Carrying currents due to faults on the capacitor side of the switch.
(B) A means shall be installed to isolate from all sources of voltage each capacitor, capacitor bank, or capacitor installation that will be removed from service as a unit. The isolating means shall provide a visible gap in the electric circuit adequate for the operating voltage.
(C) Isolating or disconnecting switches (with no interrupting rating) shall be interlocked with the load interrupting device or shall be provided with prominently displayed caution signs to prevent switching load current.
(D) For series capacitors, the proper switching shall be assured by use of at least one of the following:
(1) Mechanically sequenced isolating and bypass switches;
(2) Interlocks; or
(3) Switching procedure prominently displayed at the switching location.
(7) Storage Batteries. Provisions shall be made for sufficient diffusion and ventilation of gases from storage batteries to prevent the accumulation of explosive mixtures.
§ 1910.306 Specific purpose equipment and installations.
(a) Electric signs and outline lighting -- (1) Disconnecting means. (i) Each sign and outline lighting system, or feeder circuit or branch circuit supplying a sign or outline lighting system, shall be controlled by an externally operable switch or circuit breaker that will open all ungrounded conductors. However, a disconnecting means is not required for an exit directional sign located within a building or for cord-connected signs with an attachment plug.
(ii) Signs and outline lighting systems located within fountains shall have the disconnect located at least 1.52 m (5.0 ft) from the inside walls of the fountain.
(2) Location. (i) The disconnecting means shall be within sight of the sign or outline lighting system that it controls. Where the disconnecting means is out of the line of sight from any section that may be energized, the disconnecting means shall be capable of being locked in the open position.
(ii) Signs or outline lighting systems operated by electronic or electromechanical controllers located external to the sign or outline lighting system may have a disconnecting means located within sight of the controller or in the same enclosure with the controller. The disconnecting means shall disconnect the sign or outline lighting system and the controller from all ungrounded supply conductors. It shall be designed so no pole can be operated independently and shall be capable of being locked in the open position.
(iii) Doors or covers giving access to uninsulated parts of indoor signs or outline lighting exceeding 600 volts and accessible to other than qualified persons shall either be provided with interlock switches to disconnect the primary circuit or shall be so fastened that the use of other than ordinary tools will be necessary to open them.
(b) Cranes and hoists. This paragraph applies to the installation of electric equipment and wiring used in connection with cranes, monorail hoists, hoists, and all runways.
(1) Disconnecting means for runway conductors. A disconnecting means shall be provided between the runway contact conductors and the power supply. Such disconnecting means shall consist of a motor-circuit switch, circuit breaker, or molded case switch. The disconnecting means shall open all ungrounded conductor simultaneously and shall be:
(i) Readily accessible and operable from the ground or floor level,
(ii) Arranged to be locked in the open position; and
(iii) Placed within view of the runway contact conductors.
(2) Disconnecting means for cranes and monorail hoists. (i) Except as provided in paragraph (b)(2)(iv) of this section, a motor-circuit switch, molded case switch, or circuit breaker shall be provided in the leads from the runway contact conductors or other power supply on all cranes and monorail hoists.
(ii) The disconnecting means shall be capable of being locked in the open position.
(iii) Means shall be provided at the operating station to open the power circuit to all motors of the crane or monorail hoist where the disconnecting means is not readily accessible from the crane or monorail hoist operating station.
(iv) The disconnecting means may be omitted where a monorail hoist or hand-propelled crane bridge installation meets all of the following conditions:
(A) The unit is controlled from the ground or floor level;
(B) The unit is within view of the power supply disconnecting means; and
(C) No fixed work platform has been provided for servicing the unit.
(3) Limit switch. A limit switch or other device shall be provided to prevent the load block from passing the safe upper limit of travel of any hoisting mechanism.
(4) Clearance. The dimension of the working space in the direction of access to live parts that may require examination, adjustment, servicing, or maintenance while alive shall be a minimum of 762 mm (2.5 ft). Where controls are enclosed in cabinets, the doors shall either open at least 90 degrees or be removable.
(c) Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts. The following requirements apply to elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts.
(1) Disconnecting means. Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts shall have a single means for disconnecting all ungrounded main power supply conductors for each unit.
(2) Control panels. Control panels not located in the same space as the drive machine shall be located in cabinets with doors or panels capable of being locked closed.
(3) Type. The disconnecting means shall be an enclosed externally operable fused motor circuit switch or circuit breaker capable of being locked in the open position. The disconnecting means shall be a listed device.
(4) Operation. No provision may be made to open or close this disconnecting means from any other part of the premises. If sprinklers are installed in hoistways, machine rooms, or machinery spaces, the disconnecting means may automatically open the power supply to the affected elevators prior to the application of water. No provision may be made to close this disconnecting means automatically (that is, power may only be restored by manual means).
(5) Location. The disconnecting means shall be located where it is readily accessible to qualified persons.
(i) On elevators without generator field control, the disconnecting means shall be located within sight of the motor controller. Driving machines or motion and operation controllers not within sight of the disconnecting means shall be provided with a manually operated switch installed in the control circuit adjacent to the equipment in order to prevent starting. Where the driving machine is located in a remote machinery space, a single disconnecting means for disconnecting all ungrounded main power supply conductors shall be provided and be capable of being locked in the open position.
(ii) On elevators with generator field control, the disconnecting means shall be located within sight of the motor controller for the driving motor of the motor-generator set. Driving machines, motor-generator sets, or motion and operation controllers not within sight of the disconnecting means shall be provided with a manually operated switch installed in the control circuit to prevent starting. The manually operated switch shall be installed adjacent to this equipment. Where the driving machine or the motor-generator set is located in a remote machinery space, a single means for disconnecting all ungrounded main power supply conductors shall be provided and be capable of being locked in the open position.
(iii) On escalators and moving walks, the disconnecting means shall be installed in the space where the controller is located.
(iv) On wheelchair lifts and stairway chair lifts, the disconnecting means shall be located within sight of the motor controller.
(6) Identification and signs. (i) Where there is more than one driving machine in a machine room, the disconnecting means shall be numbered to correspond to the identifying number of the driving machine that they control.
(ii) The disconnecting means shall be provided with a sign to identify the location of the supply-side overcurrent protective device.
(7) Single-car and multicar installations. On single-car and multicar installations, equipment receiving electrical power from more than one source shall be provided with a disconnecting means for each source of electrical power. The disconnecting means shall be within sight of the equipment served.
(8) Warning sign for multiple disconnecting means. A warning sign shall be mounted on or next to the disconnecting means where multiple disconnecting means are used and parts of the controllers remain energized from a source other than the one disconnected. The sign shall be clearly legible and shall read "WARNING -- PARTS OF THE CONTROLLER ARE NOT DEENERGIZED BY THIS SWITCH."
(9) Interconnection between multicar controllers. A warning sign worded as required in paragraph (c)(8) of this section shall be mounted on or next to the disconnecting means where interconnections between controllers are necessary for the operation of the system on multicar installations that remain energized from a source other than the one disconnected.
(10) Motor controllers. Motor controllers may be located outside the spaces otherwise required by paragraph (c) of this section, provided they are in enclosures with doors or removable panels capable of being locked closed and the disconnecting means is located adjacent to or is an integral part of the motor controller. Motor controller enclosures for escalators or moving walks may be located in the balustrade on the side located away from the moving steps or moving treadway. If the disconnecting means is an integral part of the motor controller, it shall be operable without opening the enclosure.
(d) Electric welders -- disconnecting means -- (1) Arc welders. A disconnecting means shall be provided in the supply circuit for each arc welder that is not equipped with a disconnect mounted as an integral part of the welder. The disconnecting means shall be a switch or circuit breaker, and its rating may not be less than that necessary to accommodate overcurrent protection.
(2) Resistance welder. A switch or circuit breaker shall be provided by which each resistance welder and its control equipment can be disconnected from the supply circuit. The ampere rating of this disconnecting means may not be less than the supply conductor ampacity. The supply circuit switch may be used as the welder disconnecting means where the circuit supplies only one welder.
(e) Information technology equipment -- disconnecting means. A means shall be provided to disconnect power to all electronic equipment in an information technology equipment room. There shall also be a similar means to disconnect the power to all dedicated heating, ventilating, and air-conditioning (HVAC) systems serving the room and to cause all required fire/smoke dampers to close. The control for these disconnecting means shall be grouped and identified and shall be readily accessible at the principal exit doors. A single means to control both the electronic equipment and HVAC system is permitted.
(f) X-ray equipment. This paragraph applies to X-ray equipment.
(1) Disconnecting means. (i) A disconnecting means shall be in the supply circuit. The disconnecting means shall be operable from a location readily accessible from the X-ray control. For equipment connected to a 120-volt branch circuit of 30 amperes or less, a grounding-type attachment plug cap and receptacle of proper rating may serve as a disconnecting means.
(ii) If more than one piece of equipment is operated from the same high-voltage circuit, each piece or each group of equipment as a unit shall be provided with a high-voltage switch or equivalent disconnecting means. The disconnecting means shall be constructed, enclosed, or located so as to avoid contact by employees with its live parts.
(2) Control. The following requirements apply to industrial and commercial laboratory equipment. (i) Radiographic and fluoroscopic-type equipment shall be effectively enclosed or shall have interlocks that deenergize the equipment automatically to prevent ready access to live current-carrying parts.
(ii) Diffraction- and irradiation-type equipment shall have a pilot light, readable meter deflection, or equivalent means to indicate when the equipment is energized, unless the equipment or installation is effectively enclosed or is provided with interlocks to prevent access to live current-carrying parts during operation.
(g) Induction and dielectric heating equipment. This paragraph applies to induction and dielectric heating equipment and accessories for industrial and scientific applications, but not for medical or dental applications or for appliances.
(1) Guarding and grounding. (i) The converting apparatus (including the dc line) and high-frequency electric circuits (excluding the output circuits and remote-control circuits) shall be completely contained within enclosures of noncombustible material.
(ii) All panel controls shall be of dead-front construction.
(iii) Doors or detachable panels shall be employed for internal access. Where doors are used giving access to voltages from 500 to 1000 volts ac or dc, either door locks shall be provided or interlocks shall be installed. Where doors are used giving access to voltages of over 1000 volts ac or dc, either mechanical lockouts with a disconnecting means to prevent access until circuit parts within the cubicle are deenergized, or both door interlocking and mechanical door locks, shall be provided. Detachable panels not normally used for access to such parts shall be fastened in a manner that will make them difficult to remove (for example, by requiring the use of tools).
(iv) Warning labels or signs that read "DANGER -- HIGH VOLTAGE -- KEEP OUT" shall be attached to the equipment and shall be plainly visible where persons might contact energized parts when doors are opened or closed or when panels are removed from compartments containing over 250 volts ac or dc.
(v) Induction and dielectric heating equipment shall be protected as follows:
(A) Protective cages or adequate shielding shall be used to guard work applicators other than induction heating coils.
(B) Induction heating coils shall be protected by insulation or refractory materials or both.
(C) Interlock switches shall be used on all hinged access doors, sliding panels, or other such means of access to the applicator, unless the applicator is an induction heating coil at dc ground potential or operating at less than 150 volts ac.
(D) Interlock switches shall be connected in such a manner as to remove all power from the applicator when any one of the access doors or panels is open.
(vi) A readily accessible disconnecting means shall be provided by which each heating equipment can be isolated from its supply circuit. The ampere rating of this disconnecting means may not be less than the nameplate current rating of the equipment. The supply circuit disconnecting means is permitted as a heating equipment disconnecting means where the circuit supplies only one piece of equipment.
(2) Remote control. (i) If remote controls are used for applying power, a selector switch shall be provided and interlocked to provide power from only one control point at a time.
(ii) Switches operated by foot pressure shall be provided with a shield over the contact button to avoid accidental closing of the switch.
(h) Electrolytic cells. This paragraph applies to the installation of the electrical components and accessory equipment of electrolytic cells, electrolytic cell lines, and process power supply for the production of aluminum, cadmium, chlorine, copper, fluorine, hydrogen peroxide, magnesium, sodium, sodium chlorate, and zinc. Cells used as a source of electric energy and for electroplating processes and cells used for production of hydrogen are not covered by this paragraph.
(1) Application. Installations covered by paragraph (h) of this section shall comply with all applicable provisions of this subpart, except as follows:
(i) Overcurrent protection of electrolytic cell dc process power circuits need not comply with the requirements of § 1910.304(f).
(ii) Equipment located or used within the cell line working zone or associated with the cell line dc power circuits need not comply with the provisions of § 1910.304(g).
(iii) Electrolytic cells, cell line conductors, cell line attachments, and the wiring of auxiliary equipment and devices within the cell line working zone need not comply with the provisions of § 1910.303 or § 1910.304(b) and (c).
(2) Disconnecting means. If more than one dc cell line process power supply serves the same cell line, a disconnecting means shall be provided on the cell line circuit side of each power supply to disconnect it from the cell line circuit. Removable links or removable conductors may be used as the disconnecting means.
(3) Portable electric equipment. (i) The frames and enclosures of portable electric equipment used within the cell line working zone may not be grounded, unless the cell line circuit voltage does not exceed 200 volts dc or the frames are guarded.
(ii) Ungrounded portable electric equipment shall be distinctively marked and shall employ plugs and receptacles of a configuration that prevents connection of this equipment to grounding receptacles and that prevents inadvertent interchange of ungrounded and grounded portable electric equipment.
(4) Power supply circuits and receptacles for portable electric equipment. (i) Circuits supplying power to ungrounded receptacles for hand-held, cord- and plug-connected equipment shall meet the following requirements:
(A) The circuits shall be electrically isolated from any distribution system supplying areas other than the cell line working zone and shall be ungrounded;
(B) The circuits shall be supplied through isolating transformers with primaries operating at not more than 600 volts between conductors and protected with proper overcurrent protection;
(C) The secondary voltage of the isolating transformers may not exceed 300 volts between conductors; and
(D) All circuits supplied from the secondaries shall be ungrounded and shall have an approved overcurrent device of proper rating in each conductor.
(ii) Receptacles and their mating plugs for ungrounded equipment may not have provision for a grounding conductor and shall be of a configuration that prevents their use for equipment required to be grounded.
(iii) Receptacles on circuits supplied by an isolating transformer with an ungrounded secondary:
(A) Shall have a distinctive configuration;
(B) Shall be distinctively marked; and
(C) May not be used in any other location in the facility.
(5) Fixed and portable electric equipment. (i) The following need not be grounded:
(A) AC systems supplying fixed and portable electric equipment within the cell line working zone.
(B) Exposed conductive surfaces, such as electric equipment housings, cabinets, boxes, motors, raceways and the like that are within the cell line working zone.
(ii) Auxiliary electric equipment, such as motors, transducers, sensors, control devices, and alarms, mounted on an electrolytic cell or other energized surface shall be connected to the premises wiring systems by any of the following means:
(A) Multiconductor hard usage or extra hard usage flexible cord;
(B) Wire or cable in suitable nonmetallic raceways or cable trays; or
(C) Wire or cable in suitable metal raceways or metal cable trays installed with insulating breaks such that they will not cause a potentially hazardous electrical condition.
(iii) Fixed electric equipment may be bonded to the energized conductive surfaces of the cell line, its attachments, or auxiliaries. If fixed electric equipment is mounted on an energized conductive surface, it shall be bonded to that surface.
(6) Auxiliary nonelectrical connections. Auxiliary nonelectrical connections such as air hoses, water hoses, and the like, to an electrolytic cell, its attachments, or auxiliary equipment may not have continuous conductive reinforcing wire, armor, braids, or the like. Hoses shall be of a nonconductive material.
(7) Cranes and hoists. (i) The conductive surfaces of cranes and hoists that enter the cell line working zone need not be grounded. The portion of an overhead crane or hoist that contacts an energized electrolytic cell or energized attachments shall be insulated from ground.
(ii) Remote crane or hoist controls that may introduce hazardous electrical conditions into the cell line working zone shall employ one or more of the following systems:
(A) Isolated and ungrounded control circuit;
(B) Nonconductive rope operator;
(C) Pendant pushbutton with nonconductive supporting means and with nonconductive surfaces or ungrounded exposed conductive surfaces; or
(D) Radio.
(i) Electrically driven or controlled irrigation machines -- (1) Lightning protection. If an irrigation machine has a stationary point, a grounding electrode system shall be connected to the machine at the stationary point for lightning protection.
(2) Disconnecting means. (i) The main disconnecting means for a center pivot irrigation machine shall be located at the point of connection of electrical power to the machine or shall be visible and not more than 15.2 m (50 ft) from the machine.
(ii) The disconnecting means shall be readily accessible and capable of being locked in the open position.
(iii) A disconnecting means shall be provided for each motor and controller.
(j) Swimming pools, fountains, and similar installations. This paragraph applies to electric wiring for and equipment in or adjacent to all swimming, wading, therapeutic, and decorative pools and fountains; hydro-massage bathtubs, whether permanently installed or storable; and metallic auxiliary equipment, such as pumps, filters, and similar equipment. Therapeutic pools in health care facilities are exempt from these provisions.
(1) Receptacles. (i) A single receptacle of the locking and grounding type that provides power for a permanently installed swimming pool recirculating pump motor may be located not less than 1.52 m (5 ft) from the inside walls of a pool. All other receptacles on the property shall be located at least 3.05 m (10 ft) from the inside walls of a pool.
(ii) Receptacles that are located within 4.57 m (15 ft), or 6.08 m (20 ft) if the installation was built after the effective date of this standard, of the inside walls of the pool shall be protected by ground-fault circuit interrupters.
(iii) Where a pool is installed permanently at a dwelling unit, at least one 125-volt, 15- or 20-ampere receptacle on a general-purpose branch circuit shall be located a minimum of 3.05 m (10 ft) and not more than 6.08 m (20 ft) from the inside wall of the pool. This receptacle shall be located not more than 1.98 m (6.5 ft) above the floor, platform, or grade level serving the pool.
Note to paragraph (j)(1) of this section: In determining these dimensions, the distance to be measured is the shortest path the supply cord of an appliance connected to the receptacle would follow without piercing a floor, wall, or ceiling of a building or other effective permanent barrier.
(2) Lighting fixtures, lighting outlets, and ceiling suspended (paddle) fans. (i) In outdoor pool areas, lighting fixtures, lighting outlets, and ceiling-suspended (paddle) fans may not be installed over the pool or over the area extending 1.52 m (5 ft) horizontally from the inside walls of a pool unless no part of the lighting fixture of ceiling-suspended (paddle) fan is less than 3.66 m (12 ft) above the maximum water level. However, a lighting fixture or lighting outlet that was installed before April 16, 1981, may be located less than 1.52 m (5 ft) measured horizontally from the inside walls of a pool if it is at least 1.52 m (5 ft) above the surface of the maximum water level and is rigidly attached to the existing structure. It shall also be protected by a ground-fault circuit interrupter installed in the branch circuit supplying the fixture.
(ii) Lighting fixtures and lighting outlets installed in the area extending between 1.52 m (5 ft) and 3.05 m (10 ft) horizontally from the inside walls of a pool shall be protected by a ground-fault circuit interrupter unless installed 1.52 m (5 ft) above the maximum water level and rigidly attached to the structure adjacent to or enclosing the pool.
(3) Cord- and plug-connected equipment. Flexible cords used with the following equipment may not exceed 0.9 m (3 ft) in length and shall have a copper equipment grounding conductor with a grounding-type attachment plug:
(i) Cord- and plug-connected lighting fixtures installed within 4.88 m (16 ft) of the water surface of permanently installed pools; and
(ii) Other cord- and plug-connected, fixed or stationary equipment used with permanently installed pools.
(4) Underwater equipment. (i) A ground-fault circuit interrupter shall be installed in the branch circuit supplying underwater fixtures operating at more than 15 volts. Equipment installed underwater shall be identified for the purpose.
(ii) No underwater lighting fixtures may be installed for operation at over 150 volts between conductors.
(iii) A lighting fixture facing upward shall have the lens adequately guarded to prevent contact by any person.
(5) Fountains. All electric equipment, including power supply cords, operating at more than 15 volts and used with fountains shall be protected by ground-fault circuit interrupters.
(k) Carnivals, circuses, fairs, and similar events. This paragraph covers the installation of portable wiring and equipment, including wiring in or on all structures, for carnivals, circuses, exhibitions, fairs, traveling attractions, and similar events.
(1) Protection of electric equipment. Electric equipment and wiring methods in or on rides, concessions, or other units shall be provided with mechanical protection where such equipment or wiring methods are subject to physical damage.
(2) Installation. (i) Services shall be installed in accordance with applicable requirements of this subpart, and, in addition, shall comply with the following:
(A) Service equipment may not be installed in a location that is accessible to unqualified persons, unless the equipment is lockable.
(B) Service equipment shall be mounted on solid backing and installed so as to be protected from the weather, unless the equipment is of weatherproof construction.
(ii) Amusement rides and amusement attractions shall be maintained not less than 4.57 m (15 ft) in any direction from overhead conductors operating at 600 volts or less, except for the conductors supplying the amusement ride or attraction. Amusement rides or attractions may not be located under or within 4.57 m (15 ft) horizontally of conductors operating in excess of 600 volts.
(iii) Flexible cords and cables shall be listed for extra-hard usage. When used outdoors, flexible cords and cables shall also be listed for wet locations and shall be sunlight resistant.
(iv) Single conductor cable shall be size No. 2 or larger.
(v) Open conductors are prohibited except as part of a listed assembly or festoon lighting installed in accordance with § 1910.304(c).
(vi) Flexible cords and cables shall be continuous without splice or tap between boxes or fittings. Cord connectors may not be laid on the ground unless listed for wet locations. Connectors and cable connections may not be placed in audience traffic paths or within areas accessible to the public unless guarded.
(vii) Wiring for an amusement ride, attraction, tent, or similar structure may not be supported by another ride or structure unless specifically identified for the purpose.
(viii) Flexible cords and cables run on the ground, where accessible to the public, shall be covered with approved nonconductive mats. Cables and mats shall be arranged so as not to present a tripping hazard.
(ix) A box or fitting shall be installed at each connection point, outlet, switch point, or junction point.
(3) Inside tents and concessions. Electrical wiring for temporary lighting, where installed inside of tents and concessions, shall be securely installed, and, where subject to physical damage, shall be provided with mechanical protection. All temporary lamps for general illumination shall be protected from accidental breakage by a suitable fixture or lampholder with a guard.
(4) Portable distribution and termination boxes. Employers may only use portable distribution and termination boxes that meet the following requirements:
(i) Boxes shall be designed so that no live parts are exposed to accidental contact. Where installed outdoors the box shall be of weatherproof construction and mounted so that the bottom of the enclosure is not less 152 mm (6 in.) above the ground.
(ii) Busbars shall have an ampere rating not less than the overcurrent device supplying the feeder supplying the box. Busbar connectors shall be provided where conductors terminate directly on busbars.
(iii) Receptacles shall have overcurrent protection installed within the box. The overcurrent protection may not exceed the ampere rating of the receptacle, except as permitted in § 1910.305(j)(4) for motor loads.
(iv) Where single-pole connectors are used, they shall comply with the following:
(A) Where ac single-pole portable cable connectors are used, they shall be listed and of the locking type. Where paralleled sets of current-carrying single-pole separable connectors are provided as input devices, they shall be prominently labeled with a warning indicating the presence of internal parallel connections. The use of single-pole separable connectors shall comply with at least one of the following conditions:
(1) Connection and disconnection of connectors are only possible where the supply connectors are interlocked to the source and it is not possible to connect or disconnect connectors when the supply is energized; or
(2) Line connectors are of the listed sequential-interlocking type so that load connectors are connected in the following sequence:
(i) Equipment grounding conductor connection;
(ii) Grounded circuit-conductor connection, if provided;
(iii) Ungrounded conductor connection; and so that disconnection is in the reverse order; or
(3) A caution notice is provided adjacent to the line connectors indicating that plug connection must be in the following sequence:
(iii) Ungrounded conductor connection; and indicating that disconnection is in the reverse order.
(B) Single-pole separable connectors used in portable professional motion picture and television equipment may be interchangeable for ac or dc use or for different current ratings on the same premises only if they are listed for ac/dc use and marked to identify the system to which they are connected.
(v) Overcurrent protection of equipment and conductors shall be provided.
(vi) The following equipment connected to the same source shall be bonded:
(A) Metal raceways and metal sheathed cable,
(B) Metal enclosures of electrical equipment, and
(C) Metal frames and metal parts of rides, concessions, trailers, trucks, or other equipment that contain or support electrical equipment.
(5) Disconnecting means. (i) Each ride and concession shall be provided with a fused disconnect switch or circuit breaker located within sight and within 1.83 m (6 ft) of the operator's station.
(ii) The disconnecting means shall be readily accessible to the operator, including when the ride is in operation.
(iii) Where accessible to unqualified persons, the enclosure for the switch or circuit breaker shall be of the lockable type.
(iv) A shunt trip device that opens the fused disconnect or circuit breaker when a switch located in the ride operator's console is closed is a permissible method of opening the circuit.
§ 1910.307 Hazardous (classified) locations.
(a) Scope. (1) This section covers the requirements for electric equipment and wiring in locations that are classified depending on the properties of the flammable vapors, liquids or gases, or combustible dusts or fibers that may be present therein and the likelihood that a flammable or combustible concentration or quantity is present.
Hazardous (classified) locations may be found in occupancies such as, but not limited to, the following: aircraft hangars, gasoline dispensing and service stations, bulk storage plants for gasoline or other volatile flammable liquids, paint-finishing process plants, health care facilities, agricultural or other facilities where excessive combustible dusts may be present, marinas, boat yards, and petroleum and chemical processing plants. Each room, section or area shall be considered individually in determining its classification.
(2) These hazardous (classified) locations are assigned the following designations:
Class I, Division 1;
Class I, Zone 0;
Class II, Division 1;
Class III, Division 1;
Class III, Division 2.
For definitions of these locations see § 1910.399.
(3) All applicable requirements in this subpart apply to hazardous (classified) locations unless modified by provisions of this section.
(4) In Class I locations, an installation must be classified as using the division classification system meeting paragraphs (c), (d), (e) and (f) of this section or using the zone classification system meeting paragraph (g) of this section. In Class II and Class III locations, an installation must be classified using the division classification system meeting paragraphs (c), (d), (e) and (f) of this section.
(b) Documentation. All areas designated as hazardous (classified) locations under the Class and Zone system and areas designated under the Class and Division system established after the effective date of the standard shall be properly documented. This documentation shall be available to those authorized to design, install, inspect, maintain, or operate electric equipment at the location.
(c) Electrical installations. Equipment, wiring methods, and installations of equipment in hazardous (classified) locations shall be intrinsically safe, approved for the hazardous (classified) location, or safe for the hazardous (classified) location. Requirements for each of these options are as follows:
(1) Intrinsically safe. Equipment and associated wiring approved as intrinsically safe is permitted in any hazardous (classified) location for which it is approved.
(2) Approved for the hazardous (classified) location. (i) Equipment shall be approved not only for the class of location, but also for the ignitable or combustible properties of the specific gas, vapor, dust, or fiber that will be present.
Note to paragraph (c)(2)(i) of this section: NFPA 70, the National Electrical Code, lists or defines hazardous gases, vapors, and dusts by "Groups" characterized by their ignitable or combustible properties.
(ii) Equipment shall be marked to show the class, group, and operating temperature or temperature range, based on operation in a 40-degree C ambient, for which it is approved. The temperature marking may not exceed the ignition temperature of the specific gas or vapor to be encountered. However, the following provisions modify this marking requirement for specific equipment:
(A) Equipment of the nonheat-producing type, such as junction boxes, conduit, and fittings, and equipment of the heat-producing type having a maximum temperature not more than 100 °C (212 °F) need not have a marked operating temperature or temperature range.
(B) Fixed lighting fixtures marked for use in Class I, Division 2 or Class II, Division 2 locations only need not be marked to indicate the group.
(C) Fixed general-purpose equipment in Class I locations, other than lighting fixtures, that is acceptable for use in Class I, Division 2 locations need not be marked with the class, group, division, or operating temperature.
(D) Fixed dust-tight equipment, other than lighting fixtures, that is acceptable for use in Class II, Division 2 and Class III locations need not be marked with the class, group, division, or operating temperature.
(E) Electric equipment suitable for ambient temperatures exceeding 40 °C (104 °F) shall be marked with both the maximum ambient temperature and the operating temperature or temperature range at that ambient temperature.
(3) Safe for the hazardous (classified) location. Equipment that is safe for the location shall be of a type and design that the employer demonstrates will provide protection from the hazards arising from the combustibility and flammability of vapors, liquids, gases, dusts, or fibers.
Note to paragraph (c)(3) of this section: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that will meet this requirement. Those guidelines address electric wiring, equipment, and systems installed in hazardous (classified) locations and contain specific provisions for the following: wiring methods, wiring connections; conductor insulation, flexible cords, sealing and drainage, transformers, capacitors, switches, circuit breakers, fuses, motor controllers, receptacles, attachment plugs, meters, relays, instruments, resistors, generators, motors, lighting fixtures, storage battery charging equipment, electric cranes, electric hoists and similar equipment, utilization equipment, signaling systems, alarm systems, remote control systems, local loud speaker and communication systems, ventilation piping, live parts, lightning surge protection, and grounding.
(d) Conduits. All conduits shall be threaded and shall be made wrench-tight. Where it is impractical to make a threaded joint tight, a bonding jumper shall be utilized.
(e) Equipment in Division 2 locations. Equipment that has been approved for a Division 1 location may be installed in a Division 2 location of the same class and group. General-purpose equipment or equipment in general-purpose enclosures may be installed in Division 2 locations if the employer can demonstrate that the equipment does not constitute a source of ignition under normal operating conditions.
(f) Protection techniques. The following are acceptable protection techniques for electric and electronic equipment in hazardous (classified) locations.
(1) Explosionproof apparatus. This protection technique is permitted for equipment in the Class I, Division 1 and 2 locations for which it is approved.
(2) Dust ignitionproof. This protection technique is permitted for equipment in the Class II, Division 1 and 2 locations for which it is approved.
(3) Dust-tight. This protection technique is permitted for equipment in the Class II, Division 2 and Class III locations for which it is approved.
(4) Purged and pressurized. This protection technique is permitted for equipment in any hazardous (classified) location for which it is approved.
(5) Other protection techniques. Any other protection technique that meets paragraph (c) of this section is acceptable in any hazardous (classified) location.
(g) Class I, Zone 0, 1, and 2 locations -- (1) Scope. Employers may use the zone classification system as an alternative to the division classification system for electric and electronic equipment and wiring for all voltage in Class I, Zone 0, Zone 1, and Zone 2 hazardous (classified) locations where fire or explosion hazards may exist due to flammable gases, vapors, or liquids.
(2) Location and general requirements. (i) Locations shall be classified depending on the properties of the flammable vapors, liquids, or gases that may be present and the likelihood that a flammable or combustible concentration or quantity is present. Where pyrophoric materials are the only materials used or handled, these locations need not be classified.
(ii) Each room, section, or area shall be considered individually in determining its classification.
(iii) All threaded conduit shall be threaded with an NPT standard conduit cutting die that provides 3/4-in. taper per foot. The conduit shall be made wrench tight to prevent sparking when fault current flows through the conduit system and to ensure the explosionproof or flameproof integrity of the conduit system where applicable.
(iv) Equipment provided with threaded entries for field wiring connection shall be installed in accordance with paragraph (g)(2)(iv)(A) or (g)(2)(iv)(B) of this section.
(A) For equipment provided with threaded entries for NPT threaded conduit or fittings, listed conduit, conduit fittings, or cable fittings shall be used.
(B) For equipment with metric threaded entries, such entries shall be identified as being metric, or listed adaptors to permit connection to conduit of NPT-threaded fittings shall be provided with the equipment. Adapters shall be used for connection to conduit or NPT-threaded fittings.
(3) Protection techniques. One or more of the following protection techniques shall be used for electric and electronic equipment in hazardous (classified) locations classified under the zone classification system:
(i) Flameproof "d"--This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
(ii) Purged and pressurized--This protection technique is permitted for equipment in the Class I, Zone 1 or Zone 2 locations for which it is approved.
(iii) Intrinsic safety--This protection technique is permitted for equipment in the Class I, Zone 0 or Zone 1 locations for which it is approved.
(iv) Type of protection "n"--This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. Type of protection "n" is further subdivided into nA, nC, and nR.
(v) Oil Immersion "o"--This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
(vi) Increased safety "e"--This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
(vii) Encapsulation "m"--This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
(viii) Powder Filling "q"--This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
(4) Special precaution. Paragraph (g) of this section requires equipment construction and installation that will ensure safe performance under conditions of proper use and maintenance.
Note to paragraph (g)(4) of this section: Low ambient conditions require special consideration. Electric equipment depending on the protection techniques described by paragraph (g)(3)(i) of this section may not be suitable for use at temperatures lower than - 20° C (-13° F) unless they are approved for use at lower temperatures. However, at low ambient temperatures, flammable concentrations of vapors may not exist in a location classified Class I, Zone 0, 1, or 2 at normal ambient temperature.
(i) Classification of areas and selection of equipment and wiring methods shall be under the supervision of a qualified registered professional engineer.
(ii) In instances of areas within the same facility classified separately, Class I, Zone 2 locations may abut, but not overlap, Class I, Division 2 locations. Class I, Zone 0 or Zone 1 locations may not abut Class I, Division 1 or Division 2 locations.
(iii) A Class I, Division 1 or Division 2 location may be reclassified as a Class I, Zone 0, Zone 1, or Zone 2 location only if all of the space that is classified because of a single flammable gas or vapor source is reclassified.
(5) Listing and marking. (i) Equipment that is listed for a Zone 0 location may be installed in a Zone 1 or Zone 2 location of the same gas or vapor. Equipment that is listed for a Zone 1 location may be installed in a Zone 2 location of the same gas or vapor.
(ii) Equipment shall be marked in accordance with paragraph (g)(5)(ii)(A), and (g)(5)(ii)(B) of this section.
(A) Equipment approved for Class I, Division 1 or Class 1, Division 2 shall, in addition to being marked in accordance with (c)(2)(ii), be marked with the following:
(1) Class I, Zone 1 or Class I, Zone 2 (as applicable);
(2) Applicable gas classification groups; and
(3) Temperature classification; or
(B) Equipment meeting one or more of the protection techniquesdescribed in paragraph (g)(3) of this section shall be marked with thefollowing in the order shown:
(1) Class, except for intrinsically safe apparatus;
(2) Zone, except for intrinsically safe apparatus;
(3) Symbol "AEx;"
(4) Protection techniques;
(6) Temperature classification, except for intrinsically safe apparatus.
Note to paragraph (g)(5)(ii)(B) of this section: An example of such a required marking is "Class I, Zone 0, AEx ia IIC T6." See Figure S-1 for an explanation of this marking.
Example: Class I Zone 0 AEx ia IIC T6
Area Classification -----------------------------^
Symbol for equipment built to American specifications ----------------^
Type of protection designations -------------------------------------------------------------^
Gas classification group (as required) ----------------------------------------------------------------^
Temperature classification ---------------------------------------------------------------------------------------^
(a) Systems over 600 volts, nominal. This paragraph covers the general requirements for all circuits and equipment operated at over 600 volts.
(1) Aboveground wiring methods. (i) Aboveground conductors shall be installed in rigid metal conduit, in intermediate metal conduit, in electrical metallic tubing, in rigid nonmetallic conduit, in cable trays, as busways, as cablebus, in other identified raceways, or as open runs of metal-clad cable suitable for the use and purpose. In locations accessible to qualified persons only, open runs of Type MV cables, bare conductors, and bare busbars are also permitted. Busbars shall be either copper or aluminum. Open runs of insulated wires and cables having a bare lead sheath or a braided outer covering shall be supported in a manner designed to prevent physical damage to the braid or sheath.
(ii) Conductors emerging from the ground shall be enclosed in approved raceways.
(2) Braid-covered insulated conductors-open installations. The braid on open runs of braid-covered insulated conductors shall be flame retardant or shall have a flame-retardant saturant applied after installation. This treated braid covering shall be stripped back a safe distance at conductor terminals, according to the operating voltage.
(3) Insulation shielding. (i) Metallic and semiconductor insulation shielding components of shielded cables shall be removed for a distance dependent on the circuit voltage and insulation. Stress reduction means shall be provided at all terminations of factory-applied shielding.
(ii) Metallic shielding components such as tapes, wires, or braids, or combinations thereof, and their associated conducting and semiconducting components shall be grounded.
(4) Moisture or mechanical protection for metal-sheathed cables. Where cable conductors emerge from a metal sheath and where protection against moisture or physical damage is necessary, the insulation of the conductors shall be protected by a cable sheath terminating device.
(5) Interrupting and isolating devices. (i) Circuit breaker installations located indoors shall consist of metal-enclosed units or fire-resistant cell-mounted units. In locations accessible only to qualified employees, open mounting of circuit breakers is permitted. A means of indicating the open and closed position of circuit breakers shall be provided.
(ii) Where fuses are used to protect conductors and equipment, a fuse shall be placed in each ungrounded conductor. Two power fuses may be used in parallel to protect the same load, if both fuses have identical ratings, and if both fuses are installed in an identified common mounting with electrical connections that will divide the current equally. Power fuses of the vented type may not be used indoors, underground, or in metal enclosures unless identified for the use.
(iii) Fused cutouts installed in buildings or transformer vaults shall be of a type identified for the purpose. Distribution cutouts may not be used indoors, underground, or in metal enclosures. They shall be readily accessible for fuse replacement.
(iv) Where fused cutouts are not suitable to interrupt the circuit manually while carrying full load, an approved means shall be installed to interrupt the entire load. Unless the fused cutouts are interlocked with the switch to prevent opening of the cutouts under load, a conspicuous sign shall be placed at such cutouts reading: "WARNING--DO NOT OPERATE UNDER LOAD."
(v) Suitable barriers or enclosures shall be provided to prevent contact with nonshielded cables or energized parts of oil-filled cutouts.
(vi) Load interrupter switches may be used only if suitable fuses or circuits are used in conjunction with these devices to interrupt fault currents.
(A) Where these devices are used in combination, they shall be coordinated electrically so that they will safely withstand the effects of closing, carrying, or interrupting all possible currents up to the assigned maximum short-circuit rating.
(B) Where more than one switch is installed with interconnected load terminals to provide for alternate connection to different supply conductors, each switch shall be provided with a conspicuous sign reading: "WARNING--SWITCH MAY BE ENERGIZED BY BACKFEED."
(vii) A means (for example, a fuseholder and fuse designed for the purpose) shall be provided to completely isolate equipment for inspection and repairs. Isolating means that are not designed to interrupt the load current of the circuit shall be either interlocked with an approved circuit interrupter or provided with a sign warning against opening them under load.
(6) Mobile and portable equipment. (i) A metallic enclosure shall be provided on the mobile machine for enclosing the terminals of the power cable. The enclosure shall include provisions for a solid connection for the grounding terminal to effectively ground the machine frame. The method of cable termination used shall prevent any strain or pull on the cable from stressing the electrical connections. The enclosure shall have provision for locking so only authorized qualified persons may open it and shall be marked with a sign warning of the presence of energized parts.
(ii) All energized switching and control parts shall be enclosed in effectively grounded metal cabinets or enclosures. Circuit breakers and protective equipment shall have the operating means projecting through the metal cabinet or enclosure so these units can be reset without locked doors being opened. Enclosures and metal cabinets shall be locked so that only authorized qualified persons have access and shall be marked with a sign warning of the presence of energized parts. Collector ring assemblies on revolving-type machines (shovels, draglines, etc.) shall be guarded.
(7) Tunnel installations. This paragraph applies to installation and use of high-voltage power distribution and utilization equipment that is portable or mobile, such as substations, trailers, cars, mobile shovels, draglines, hoists, drills, dredges, compressors, pumps, conveyors, and underground excavators.
(i) Conductors in tunnels shall be installed in one or more of the following:
(A) Metal conduit or other metal raceway;
(B) Type MC cable; or
(C) Other approved multiconductor cable.
(ii) Multiconductor portable cable may supply mobile equipment.
(iii) Conductors and cables shall also be so located or guarded as to protect them from physical damage. An equipment grounding conductor shall be run with circuit conductors inside the metal raceway or inside the multiconductor cable jacket. The equipment grounding conductor may be insulated or bare.
(iv) Bare terminals of transformers, switches, motor controllers, and other equipment shall be enclosed to prevent accidental contact with energized parts.
(v) Enclosures for use in tunnels shall be drip-proof, weatherproof, or submersible as required by the environmental conditions.
(vi) Switch or contactor enclosures may not be used as junction boxes or raceways for conductors feeding through or tapping off to other switches, unless special designs are used to provide adequate space for this purpose.
(vii) A disconnecting means that simultaneously opens all ungrounded conductors shall be installed at each transformer or motor location.
(viii) All nonenergized metal parts of electric equipment and metal raceways and cable sheaths shall be effectively grounded and bonded to all metal pipes and rails at the portal and at intervals not exceeding 305 m (1000 ft) throughout the tunnel.
(b) Emergency power systems. This paragraph applies to circuits, systems, and equipment intended to supply power for illumination and special loads in the event of failure of the normal supply.
(1) Wiring methods. Emergency circuit wiring shall be kept entirely independent of all other wiring and equipment and may not enter the same raceway, cable, box, or cabinet or other wiring except either where common circuit elements suitable for the purpose are required, or for transferring power from the normal to the emergency source.
(2) Emergency illumination. Emergency illumination shall include all required means of egress lighting, illuminated exit signs, and all other lights necessary to provide illumination. Where emergency lighting is necessary, the system shall be so arranged that the failure of any individual lighting element, such as the burning out of a light bulb, cannot leave any space in total darkness.
(3) Signs. (i) A sign shall be placed at the service entrance equipment indicating the type and location of on-site emergency power sources. However, a sign is not required for individual unit equipment.
(ii) Where the grounded circuit conductor connected to the emergency source is connected to a grounding electrode conductor at a location remote from the emergency source, there shall be a sign at the grounding location that shall identify all emergency and normal sources connected at that location.
(c) Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits -- (1) Classification. Class 1, Class 2, and Class 3 remote control, signaling, or power-limited circuits are characterized by their usage and electrical power limitation that differentiates them from light and power circuits. These circuits are classified in accordance with their respective voltage and power limitations as summarized in paragraphs (c)(1)(i) through (c)(1)(iii) of this section.
(i) A Class 1 power-limited circuit shall be supplied from a source having a rated output of not more than 30 volts and 1000 volt-amperes.
(ii) A Class 1 remote control circuit or a Class 1 signaling circuit shall have a voltage not exceeding 600 volts; however, the power output of the source need not be limited.
(iii) The power source for a Class 2 or Class 3 circuit shall be listed equipment marked as a Class 2 or Class 3 power source, except as follows:
(A) Thermocouples do not require listing as a Class 2 power source; and
(B) A dry cell battery is considered an inherently limited Class 2 power source, provided the voltage is 30 volts or less and the capacity is less than or equal to that available from series-connected No. 6 carbon zinc cells.
(2) Marking. A Class 2 or Class 3 power supply unit shall be durably marked where plainly visible to indicate the class of supply and its electrical rating.
(3) Separation from conductors of other circuits. Cables and conductors of Class 2 and Class 3 circuits may not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting with conductors of electric light, power, Class 1, nonpower-limited fire alarm circuits, and medium power network-powered broadband communications cables.
(d) Fire alarm systems -- (1) Classifications. Fire alarm circuits shall be classified either as nonpower limited or power limited.
(2) Power sources. The power sources for use with fire alarm circuits shall be either power limited or nonlimited as follows:
(i) The power source of nonpower-limited fire alarm (NPLFA) circuits shall have an output voltage of not more than 600 volts, nominal.
(ii) The power source for a power-limited fire alarm (PLFA) circuit shall be listed equipment marked as a PLFA power source.
(3) Separation from conductors of other circuits. (i) Nonpower-limited fire alarm circuits and Class 1 circuits may occupy the same enclosure, cable, or raceway provided all conductors are insulated for maximum voltage of any conductor within the enclosure, cable, or raceway. Power supply and fire alarm circuit conductors are permitted in the same enclosure, cable, or raceway only if connected to the same equipment.
(ii) Power-limited circuit cables and conductors may not be placed in any cable, cable tray, compartment, enclosure, outlet box, raceway, or similar fitting with conductors of electric light, power, Class 1, nonpower-limited fire alarm circuit conductors, or medium power network-powered broadband communications circuits.
(iii) Power-limited fire alarm circuit conductors shall be separated at least 50.8 mm (2 in.) from conductors of any electric light, power, Class 1, nonpower-limited fire alarm, or medium power network-powered broadband communications circuits.
(iv) Conductors of one or more Class 2 circuits are permitted within the same cable, enclosure, or raceway with conductors of power-limited fire alarm circuits provided that the insulation of Class 2 circuit conductors in the cable, enclosure, or raceway is at least that needed for the power-limited fire alarm circuits.
(4) Identification. Fire alarm circuits shall be identified at terminal and junction locations in a manner that will prevent unintentional interference with the signaling circuit during testing and servicing. Power-limited fire alarm circuits shall be durably marked as such where plainly visible at terminations.
(e) Communications systems. This paragraph applies to central- station-connected and non-central-station-connected telephone circuits, radio and television receiving and transmitting equipment, including community antenna television and radio distribution systems, telegraph, district messenger, and outside wiring for fire and burglar alarm, and similar central station systems. These installations need not comply with the provisions of § 1910.303 through § 1910.308(d), except for § 1910.304(c)(1) and § 1910.307.
(1) Protective devices. (i) A listed primary protector shall be provided on each circuit run partly or entirely in aerial wire or aerial cable not confined within a block.
(ii) A listed primary protector shall be also provided on each circuit, aerial or underground, located within the block containing the building served so as to be exposed to accidental contact with electric light or power conductors operating at over 300 volts to ground.
(iii) In addition, where there exists a lightning exposure, each interbuilding circuit on premises shall be protected by a listed primary protector at each end of the interbuilding circuit.
(2) Conductor location. (i) Lead-in or aerial-drop cables from a pole or other support, including the point of initial attachment to a building or structure, shall be kept away from electric light, power, Class 1, or nonpower-limited fire alarm circuit conductors so as to avoid the possibility of accidental contact.
(ii) A separation of at least 1.83 m (6 ft) shall be maintained between communications wires and cables on buildings and lightning conductors.
(iii) Where communications wires and cables and electric light or power conductors are supported by the same pole or run parallel to each other in-span, the following conditions shall be met:
(A) Where practicable, communication wires and cables on poles shall be located below the electric light or power conductors.
(B) Communications wires and cables may not be attached to a crossarm that carries electric light or power conductors.
(iv) Indoor communications wires and cables shall be separated at least 50.8 mm (2 in.) from conductors of any electric light, power, Class 1, nonpower-limited fire alarm, or medium power network-powered broadband communications circuits, unless a special and equally protective method of conductor separation, identified for the purpose,is employed.
(3) Equipment location. Outdoor metal structures supporting antennas, as well as self-supporting antennas such as vertical rods or dipole structures, shall be located as far away from overhead conductors of electric light and power circuits of over 150 volts to ground as necessary to prevent the antenna or structure from falling into or making accidental contact with such circuits.
(4) Grounding. (i) If exposed to contact with electric light and power conductors, the metal sheath of aerial cables entering buildings shall be grounded or shall be interrupted close to the entrance to the building by an insulating joint or equivalent device. Where protective devices are used, they shall be grounded in an approved manner.
(ii) Masts and metal structures supporting antennas shall be permanently and effectively grounded without splice or connection in the grounding conductor.
(iii) Transmitters shall be enclosed in a metal frame or grill or separated from the operating space by a barrier, all metallic parts of which are effectively connected to ground. All external metal handles and controls accessible to the operating personnel shall be effectively grounded. Unpowered equipment and enclosures are considered to be grounded where connected to an attached coaxial cable with an effectively grounded metallic shield.
(f) Solar photovoltaic systems. This paragraph covers solar photovoltaic systems that can be interactive with other electric power production sources or can stand alone with or without electrical energy storage such as batteries. These systems may have ac or dc output for utilization.
(1) Conductors of different systems. Photovoltaic source circuits and photovoltaic output circuits may not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as feeders or branch circuits of other systems, unless the conductors of the different systems are separated by a partition or are connected together.
(2) Disconnecting means. Means shall be provided to disconnect all current-carrying conductors of a photovoltaic power source from all other conductors in a building or other structure. Where a circuit grounding connection is not designed to be automatically interrupted as part of the ground-fault protection system, a switch or circuit breaker used as disconnecting means may not have a pole in the grounded conductor.
(g) Integrated electrical systems -- (1) Scope. Paragraph (g) of this section covers integrated electrical systems, other than unit equipment, in which orderly shutdown is necessary to ensure safe operation. An integrated electrical system as used in this section shall be a unitized segment of an industrial wiring system where all of the following conditions are met:
(i) An orderly shutdown process minimizes employee hazard and equipment damage;
(ii) The conditions of maintenance and supervision ensure that only qualified persons will service the system; and
(iii) Effective safeguards are established and maintained.
(2) Location of overcurrent devices in or on premises. Overcurrent devices that are critical to integrated electrical systems need not be readily accessible to employees as required by § 1910.304(f)(1)(iv) if they are located with mounting heights to ensure security from operation by nonqualified persons.
5. Section 1910.399 would be revised to read as follows:
§ 1910.399 Definitions applicable to this subpart.
Acceptable. An installation or equipment is acceptable to the Assistant Secretary of Labor, and approved within the meaning of this Subpart S:
(1) If it is accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a nationally recognized testing laboratory recognized pursuant to § 1910.7; or
(2) With respect to an installation or equipment of a kind that no nationally recognized testing laboratory accepts, certifies, lists, labels, or determines to be safe, if it is inspected or tested by another Federal agency, or by a State, municipal, or other local authority responsible for enforcing occupational safety provisions of the National Electrical Code, and found in compliance with the provisions of the National Electrical Code as applied in this subpart; or
(3) With respect to custom-made equipment or related installations that are designed, fabricated for, and intended for use by a particular customer, if it is determined to be safe for its intended use by its manufacturer on the basis of test data which the employer keeps and makes available for inspection to the Assistant Secretary and his authorized representatives.
Accepted. An installation is "accepted" if it has been inspected and found by a nationally recognized testing laboratory to conform to specified plans or to procedures of applicable codes.
Accessible. (As applied to wiring methods.) Capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building. (See "concealed" and "exposed.")
Accessible. (As applied to equipment.) Admitting close approach; not guarded by locked doors, elevation, or other effective means. (See "Readily accessible.")
Ampacity. The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Appliances. Utilization equipment, generally other than industrial, normally built in standardized sizes or types, that is installed or connected as a unit to perform one or more functions.
Approved. Acceptable to the authority enforcing this subpart. The authority enforcing this subpart is the Assistant Secretary of Labor for Occupational Safety and Health. The definition of "acceptable" indicates what is acceptable to the Assistant Secretary of Labor, and therefore approved within the meaning of this subpart.
Armored cable. Type AC armored cable is a fabricated assembly of insulated conductors in a flexible metallic enclosure.
Askarel. A generic term for a group of nonflammable synthetic chlorinated hydrocarbons used as electrical insulating media. Askarels of various compositional types are used. Under arcing conditions the gases produced, while consisting predominantly of noncombustible hydrogen chloride, can include varying amounts of combustible gases depending upon the askarel type.
Attachment plug (Plug cap)(Cap). A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle.
Automatic. Self-acting, operating by its own mechanism when actuated by some impersonal influence, as, for example, a change in current strength, pressure, temperature, or mechanical configuration.
Bare conductor. See Conductor.
Barrier. A physical obstruction that is intended to prevent contact with equipment or live parts or to prevent unauthorized access to a work area.
Bathroom. An area including a basin with one or more of the following: a toilet, a tub, or a shower.
Bonding (Bonded). The permanent joining of metallic parts to form an electrically conductive path that will ensure electrical continuity and the capacity to conduct safely any current likely to be imposed.
Bonding jumper. A conductor that assures the necessary electrical conductivity between metal parts required to be electrically connected.
Branch circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlets.
Building. A structure that stands alone or is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors.
Cabinet. An enclosure designed either for surface or flush mounting, and provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.
Cable tray system. A unit or assembly of units or sections, and associated fittings forming a rigid structural system used to securely fasten or support cables and raceways. Cable tray systems include ladders, troughs, channels, solid bottom trays, and other similar structures.
Cablebus. An assembly of insulated conductors with fittings and conductor terminations in a completely enclosed, ventilated, protective metal housing.
Cell line. An assembly of electrically interconnected electrolytic cells supplied by a source of direct current power.
Cell line attachments and auxiliary equipment. Cell line attachments and auxiliary equipment include, but are not limited to, auxiliary tanks, process piping, ductwork, structural supports, exposed cell line conductors, conduits and other raceways, pumps, positioning equipment, and cell cutout or bypass electrical devices. Auxiliary equipment also includes tools, welding machines, crucibles, and other portable equipment used for operation and maintenance within the electrolytic cell line working zone. In the cell line working zone, auxiliary equipment includes the exposed conductive surfaces of ungrounded cranes and crane-mounted cell-servicing equipment.
Center pivot irrigation machine. A multi-motored irrigation machine that revolves around a central pivot and employs alignment switches or similar devices to control individual motors.
Certified. Equipment is "certified" if it bears a label, tag, or other record of certification that the equipment: (1) has been tested and found by a nationally recognized testing laboratory to meet nationally recognized standards or to be safe for use in a specified manner, or (2) is of a kind whose production is periodically inspected by a nationally recognized testing laboratory and is accepted by the laboratory as safe for its intended use.
Circuit breaker. A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.
Class I locations. Class I locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures. Class I locations include the following:
(1) Class I, Division 1. A Class I, Division 1 location is a location: (i) In which ignitable concentrations of flammable gases or vapors may exist under normal operating conditions; or (ii) in which ignitable concentrations of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or (iii) in which breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapors, and might also cause simultaneous failure of electric equipment.
Note to the definition of "Class I, Division 1:" This classification usually includes locations where volatile flammable liquids or liquefied flammable gases are transferred from one container to another; interiors of spray booths and areas in the vicinity of spraying and painting operations where volatile flammable solvents are used; locations containing open tanks or vats of volatile flammable liquids; drying rooms or compartments for the evaporation of flammable solvents; locations containing fat and oil extraction equipment using volatile flammable solvents; portions of cleaning and dyeing plants where flammable liquids are used; gas generator rooms and other portions of gas manufacturing plants where flammable gas may escape; inadequately ventilated pump rooms for flammable gas or for volatile flammable liquids; the interiors of refrigerators and freezers in which volatile flammable materials are lightly stoppered, or easily ruptured containers; and all other locations where ignitable concentrations of flammable vapors or gases are likely to occur in the course of normal operations.
(2) Class I, Division 2. A Class I, Division 2 location is a location: (i) In which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the hazardous liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in the event of accidental rupture or breakdown of such containers or systems, or as a result of abnormal operation of equipment; or (ii) in which ignitable concentrations of gases or vapors are normally prevented by positive mechanical ventilation, and which might become hazardous through failure or abnormal operations of the ventilating equipment; or (iii) that is adjacent to a Class I, Division 1 location, and to which ignitable concentrations of gases or vapors might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided.
Note to the definition of "Class I, Division 2:" This classification usually includes locations where volatile flammable liquids or flammable gases or vapors are used, but which would become hazardous only in case of an accident or of some unusual operating condition. The quantity of flammable material that might escape in case of accident, the adequacy of ventilating equipment, the total area involved, and the record of the industry or business with respect to explosions or fires are all factors that merit consideration in determining the classification and extent of each location.
Piping without valves, checks, meters, and similar devices would not ordinarily introduce a hazardous condition even though used for flammable liquids or gases. Locations used for the storage of flammable liquids or a liquefied or compressed gases in sealed containers would not normally be considered hazardous unless also subject to other hazardous conditions.
Electrical conduits and their associated enclosures separated from process fluids by a single seal or barrier are classed as a Division 2 location if the outside of the conduit and enclosures is a nonhazardous location.
(3) Class I, Zone 0. A Class I, Zone 0 location is a location in which one of the following conditions exists:
(i) Ignitable concentrations of flammable gases or vapors are present continuously, or
(ii) Ignitable concentrations of flammable gases or vapors are present for long periods of time.
Note to the definition of "Class I, Zone 0:" As a guide in determining when flammable gases or vapors are present continuously or for long periods of time, refer to Recommended Practice for Classification of Locations for Electrical Installations of Petroleum Facilities Classified as Class I, Zone 0, Zone 1 or Zone 2, API RP 505-1996; Electrical Apparatus for Explosive Gas Atmospheres, Classifications of Hazardous Areas, IEC 79-10-1995; Area Classification Code for Petroleum Installations, Model Code -- Part 15, Institute for Petroleum; and Electrical Apparatus for Explosive Gas Atmospheres, Classifications of Hazardous (Classified) Locations, ISA S12.24.01-1997.
(i) Ignitable concentrations of flammable gases or vapors arelikely to exist under normal operating conditions; or
(ii) Ignitable concentrations of flammable gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or
(iii) Equipment is operated or processes are carried on of such a nature that equipment breakdown or faulty operations could result in the release of ignitable concentrations of flammable gases or vapors and also cause simultaneous failure of electric equipment in a manner that would cause the electric equipment to become a source of ignition; or
(iv) A location that is adjacent to a Class I, Zone 0 location from which ignitable concentrations of vapors could be communicated, unless communication is prevented by adequate positive pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.
(i) Ignitable concentrations of flammable gases or vapors are not likely to occur in normal operation and if they do occur will exist only for a short period; or
(ii) Volatile flammable liquids, flammable gases, or flammable vapors are handled, processed, or used, but in which the liquids, gases, or vapors are normally confined within closed containers or closed systems from which they can escape only as a result of accidental rupture or breakdown of the containers or system or as the result of the abnormal operation of the equipment with which the liquids or gases are handled, processed, or used; or
(iii) Ignitable concentrations of flammable gases or vapors normally are prevented by positive mechanical ventilation, but which may become hazardous as the result of failure or abnormal operation of the ventilation equipment; or
(iv) A location that is adjacent to a Class I, Zone 1 location, from which ignitable concentrations of flammable gases or vapors could be communicated, unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided.
Class II locations. Class II locations are those that are hazardous because of the presence of combustible dust. Class II locations include the following:
(1) Class II, Division 1. A Class II, Division 1 location is a location: (i) In which combustible dust is or may be in suspension in the air under normal operating conditions, in quantities sufficient to produce explosive or ignitable mixtures; or (ii) where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitable mixtures to be produced, and might also provide a source of ignition through simultaneous failure of electric equipment, through operation of protection devices, or from other causes; or (iii) in which combustible dusts of an electrically conductive nature may be present.
Note to the definition of "Class II, Division 1": This classification may include areas of grain handling and processing plants, starch plants, sugar-pulverizing plants, malting plants, hay-grinding plants, coal pulverizing plants, areas where metal dusts and powders are produced or processed, and other similar locations that contain dust producing machinery and equipment (except where the equipment is dust-tight or vented to the outside). These areas would have combustible dust in the air, under normal operating conditions, in quantities sufficient to produce explosive or ignitable mixtures. Combustible dusts that are electrically nonconductive include dusts produced in the handling and processing of grain and grain products, pulverized sugar and cocoa, dried egg and milk powders, pulverized spices, starch and pastes, potato and wood flour, oil meal from beans and seed, dried hay, and other organic materials which may produce combustible dusts when processed or handled. Dusts containing magnesium or aluminum are particularly hazardous, and the use of extreme caution is necessary to avoid ignition and explosion.
(2) Class II, Division 2. A Class II, Division 2 location is a location where: (i) Combustible dust will not normally be in suspension in the air in quantities sufficient to produce explosive or ignitable mixtures, and dust accumulations will normally be insufficient to interfere with the normal operation of electric equipment or other apparatus, but combustible dust may be in suspension in the air as a result of infrequent malfunctioning of handling or processing equipment, and (ii) resulting combustible dust accumulations on, in, or in the vicinity of the electric equipment may be sufficient to interfere with the safe dissipation of heat from electric equipment or may be ignitable by abnormal operation or failure of electric equipment.
Note to the definition of "Class II, Division 2": This classification includes locations where dangerous concentrations of suspended dust would not be likely, but where dust accumulations might form on or in the vicinity of electric equipment. These areas may contain equipment from which appreciable quantities of dust would escape under abnormal operating conditions or be adjacent to a Class II Division 1 location, as described above, into which an explosive or ignitable concentration of dust may be put into suspension under abnormal operating conditions.
Class III locations. Class III locations are those that are hazardous because of the presence of easily ignitable fibers or flyings, but in which such fibers or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitable mixtures. Class III locations include the following:
(1) Class III, Division 1. A Class III, Division 1 location is a location in which easily ignitable fibers or materials producing combustible flyings are handled, manufactured, or used.
Note to the definition of "Class III, Division 1": Such locations usually include some parts of rayon, cotton, and other textile mills; combustible fiber manufacturing and processing plants; cotton gins and cotton-seed mills; flax-processing plants; clothing manufacturing plants; woodworking plants, and establishments; and industries involving similar hazardous processes or conditions.
Easily ignitable fibers and flyings include rayon, cotton (including cotton linters and cotton waste), sisal or henequen, istle, jute, hemp, tow, cocoa fiber, oakum, baled waste kapok, Spanish moss, excelsior, and other materials of similar nature.
(2) Class III, Division 2. A Class III, Division 2 location is a location in which easily ignitable fibers are stored or handled, other than in the process of manufacture.
Collector ring. An assembly of slip rings for transferring electric energy from a stationary to a rotating member.
Concealed. Rendered inaccessible by the structure or finish of the building. Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them. (See Accessible. (As applied to wiring methods.))
Conductor -- (1) Bare. A conductor having no covering or electrical insulation whatsoever.
(2) Covered. A conductor encased within material of composition or thickness that is not recognized by this subpart as electrical insulation.
(3) Insulated. A conductor encased within material of composition and thickness that is recognized by this subpart as electrical insulation.
Conduit body. A separate portion of a conduit or tubing system that provides access through one or more removable covers to the interior of the system at a junction of two or more sections of the system or at a terminal point of the system. Boxes such as FS and FD or larger cast or sheet metal boxes are not classified as conduit bodies.
Controller. A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected.
Covered conductor. See Conductor.
Cutout. (Over 600 volts, nominal.) An assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade by the inclusion of a nonfusible member.
Cutout box. An enclosure designed for surface mounting and having swinging doors or covers secured directly to and telescoping with the walls of the box proper. (See Cabinet.)
Damp location. See Location.
Dead front. Without live parts exposed to a person on the operating side of the equipment
Deenergized. Free from any electrical connection to a source of potential difference and from electrical charge; not having a potential different from that of the earth.
Device. A unit of an electrical system that is intended to carry but not utilize electric energy.
Dielectric heating. The heating of a nominally insulating material due to its own dielectric losses when the material is placed in a varying electric field.
Disconnecting means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
Disconnecting (or Isolating) switch. (Over 600 volts, nominal.) A mechanical switching device used for isolating a circuit or equipment from a source of power.
Electrolytic cell line working zone. The cell line working zone is the space envelope wherein operation or maintenance is normally performed on or in the vicinity of exposed energized surfaces of electrolytic cell lines or their attachments.
Electrolytic cells. A tank or vat in which electrochemical reactions are caused by applying energy for the purpose of refining or producing usable materials.
Enclosed. Surrounded by a case, housing, fence or walls that will prevent persons from accidentally contacting energized parts.
Enclosure. The case or housing of apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts, or to protect the equipment from physical damage.
Energized. Electrically connected to a source of potential difference.
Equipment. A general term including material, fittings, devices, appliances, fixtures, apparatus, and the like, used as a part of, or in connection with, an electrical installation.
Equipment grounding conductor. See Grounding conductor, equipment.
Explosion-proof apparatus. Apparatus enclosed in a case that is capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within, and that operates at such an external temperature that it will not ignite a surrounding flammable atmosphere.
Exposed. (As applied to live parts.) Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts not suitably guarded, isolated, or insulated. (See Accessible and Concealed.)
Exposed. (As applied to wiring methods.) On or attached to the surface, or behind panels designed to allow access. (See Accessible. (As applied to wiring methods.))
Exposed. (For the purposes of § 1910.308(e).) Where the circuit is in such a position that in case of failure of supports or insulation, contact with another circuit may result.
Externally operable. Capable of being operated without exposing the operator to contact with live parts.
Feeder. All circuit conductors between the service equipment, the source of a separate derived system, or other power supply source and the final branch-circuit overcurrent device.
Fitting. An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.
Fuse. (Over 600 volts, nominal.) An overcurrent protective device with a circuit opening fusible part that is heated and severed by the passage of overcurrent through it. A fuse comprises all the parts that form a unit capable of performing the prescribed functions. It may or may not be the complete device necessary to connect it into an electrical circuit.
Ground. A conducting connection, whether intentional or accidental, between an electric circuit or equipment and the earth, or to some conducting body that serves in place of the earth.
Grounded. Connected to the earth or to some conducting body that serves in place of the earth.
Grounded, effectively. (Over 600 volts, nominal.) Permanently connected to earth through a ground connection of sufficiently low impedance and having sufficient ampacity that ground fault current that may occur cannot build up to voltages dangerous to personnel.
Grounded conductor. A system or circuit conductor that is intentionally grounded.
Grounding conductor. A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.
Grounding conductor, equipment. The conductor used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately derived system.
Grounding electrode conductor. The conductor used to connect the grounding electrode to the equipment grounding conductor, to the grounded conductor, or to both, of the circuit at the service equipment or at the source of a separately derived system.
Ground-fault circuit-interrupter. A device intended for the protection of personnel that functions to deenergize a circuit or a portion of a circuit within an established period of time when a current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit.
Guarded. Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach to a point of danger or contact by persons or objects.
Health care facilities. Buildings or portions of buildings and mobile homes that contain, but are not limited to, hospitals, nursing homes, extended care facilities, clinics, and medical and dental offices, whether fixed or mobile.
Heating equipment. For the purposes of § 1910.306(g), the term "heating equipment" includes any equipment used for heating purposes if heat is generated by induction or dielectric methods.
Hoistway. Any shaftway, hatchway, well hole, or other vertical opening or space that is designed for the operation of an elevator or dumbwaiter.
Identified (as applied to equipment). Approved as suitable for the specific purpose, function, use, environment, or application, where described in a particular requirement.
Note to the definition of "identified": Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a nationally recognized testing laboratory (through listing and labeling), and inspection agency, or other organization recognized under the definition of "acceptable."
Induction heating. The heating of a nominally conductive material due to its own I2R losses when the material is placed in a varying electromagnetic field.
Insulated. Separated from other conducting surfaces by a dielectric (including air space) offering a high resistance to the passage of current.
Insulated conductor. See Conductor, Insulated.
Interrupter switch. (Over 600 volts, nominal.) A switch capable of making, carrying, and interrupting specified currents.
Irrigation Machine. An electrically driven or controlled machine, with one or more motors, not hand portable, and used primarily to transport and distribute water for agricultural purposes.
Isolated. (As applied to location.) Not readily accessible to persons unless special means for access are used.
Isolated power system. A system comprising an isolating transformer or its equivalent, a line isolation monitor, and its ungrounded circuit conductors.
Labeled. Equipment is "labeled" if there is attached to it a label, symbol, or other identifying mark of a nationally recognized testing laboratory:
(1) That makes periodic inspections of the production of such equipment, and
(2) Whose labeling indicates compliance with nationally recognized standards or tests to determine safe use in a specified manner.
Lighting outlet. An outlet intended for the direct connection of a lampholder, a lighting fixture, or a pendant cord terminating in a lampholder.
Line-clearance tree trimming. The pruning, trimming, repairing, maintaining, removing, or clearing of trees or cutting of brush that is within 305 cm (10 ft) of electric supply lines and equipment.
Listed. Equipment is "listed" if it is of a kind mentioned in a list that:
(1) Is published by a nationally recognized laboratory that makes periodic inspection of the production of such equipment, and
(2) States that such equipment meets nationally recognized standards or has been tested and found safe for use in a specified manner.
Live parts. Electric conductors, buses, terminals, or components that are energized.
Location -- (1) Damp location. Partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.
(2) Dry location. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.
(3) Wet location. Installations underground or in concrete slabs or masonry in direct contact with the earth, and locations subject to saturation with water or other liquids, such as vehicle-washing areas, and locations unprotected and exposed to weather.
Medium voltage cable. Type MV cable is a single or multiconductor solid dielectric insulated cable rated 2001 volts or higher.
Metal-clad cable. Type MC cable is a factory assembly of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal tape, or a smooth or corrugated metallic sheath.
Mineral-insulated metal-sheathed cable. Type MI, mineral-insulated metal-sheathed, cable is a factory assembly of one or more conductors insulated with a highly compressed refractory mineral insulation and enclosed in a liquidtight and gastight continuous copper sheath.
Mobile X-ray. X-ray equipment mounted on a permanent base with wheels or casters or both for moving while completely assembled.
Motor control center. An assembly of one or more enclosed sections having a common power bus and principally containing motor control units.
Nonmetallic-sheathed cable. Nonmetallic-sheathed cable is a factory assembly of two or more insulated conductors having an outer sheath of moisture resistant, flame-retardant, nonmetallic material. Nonmetallic sheathed cable is manufactured in the following types:
(1) Type NM. The overall covering has a flame-retardant and moisture-resistant finish.
(2) Type NMC. The overall covering is flame-retardant, moisture-resistant, fungus-resistant, and corrosion-resistant.
Oil (filled) cutout. (Over 600 volts, nominal.) A cutout in which all or part of the fuse support and its fuse link or disconnecting blade are mounted in oil with complete immersion of the contacts and the fusible portion of the conducting element (fuse link), so that arc interruption by severing of the fuse link or by opening of the contacts will occur under oil.
Open wiring on insulators. Open wiring on insulators is an exposed wiring method using cleats, knobs, tubes, and flexible tubing for the protection and support of single insulated conductors run in or on buildings, and not concealed by the building structure.
Outlet. A point on the wiring system at which current is taken to supply utilization equipment.
Outline lighting. An arrangement of incandescent lamps or electric discharge lighting to outline or call attention to certain features, such as the shape of a building or the decoration of a window.
Overcurrent. Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault.
Overload. Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload. (See Overcurrent.)
Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel; including buses, automatic overcurrent devices, and with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front. (See Switchboard.)
Permanently installed decorative fountains and reflection pools. Pools that are constructed in the ground, on the ground, or in a building in such a manner that the fountain or pool cannot be readily disassembled for storage, whether or not served by electrical circuits of any nature. These units are primarily constructed for their aesthetic value and are not intended for swimming or wading.
Permanently installed swimming, wading, and therapeutic pools. Pools that are constructed in the ground or partially in the ground, and all other capable of holding water in a depth greater than 1.07 m (42 in.). The definition also applies to all pools installed inside of a building, regardless of water depth, whether or not served by electric circuits of any nature.
Portable X-ray. X-ray equipment designed to be hand-carried.
Power and control tray cable. Type TC power and control tray cable is a factory assembly of two or more insulated conductors, with or without associated bare or covered grounding conductors under a nonmetallic sheath, approved for installation in cable trays, in raceways, or where supported by a messenger wire.
Power fuse. (Over 600 volts, nominal.) See Fuse.
Power-limited tray cable. Type PLTC nonmetallic-sheathed power limited tray cable is a factory assembly of two or more insulated conductors under a nonmetallic jacket.
Power outlet. An enclosed assembly, which may include receptacles, circuit breakers, fuseholders, fused switches, buses, and watt-hour meter mounting means, that is intended to supply and control power to mobile homes, recreational vehicles, or boats or to serve as a means for distributing power needed to operate mobile or temporarily installed equipment.
Premises wiring. (Premises wiring system.) That interior and exterior wiring, including power, lighting, control, and signal circuit wiring together with all of their associated hardware, fittings, and wiring devices, both permanently and temporarily installed, that extends from the service point of utility conductors or source of power such as a battery, a solar photovoltaic system, or a generator, transformer, or converter to the outlets. Such wiring does not include wiring internal to appliances, fixtures, motors, controllers, motor control centers, and similar equipment.
Qualified person. A person who is familiar with the construction and operation of the equipment and the hazards involved.
Note 1 to the definition of "qualified person:" Whether an employee is considered to be a "qualified person" will depend upon various circumstances in the workplace. It is possible and, in fact, likely for an individual to be considered "qualified" with regard to certain equipment in the workplace, but "unqualified" as to other equipment.(See 1910.332(b)(3) for training requirements that specifically apply to qualified persons.)
Note 2 to the definition of "qualified person:" An employee who is undergoing on-the-job training and who, in the course of such training, has demonstrated an ability to perform duties safely at his or her level of training and who is under the direct supervision of a qualified person is considered to be a qualified person for the performance of those duties.
Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this standard. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical metallic tubing, electrical nonmetallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
Readily accessible. Capable of being reached quickly for operation, renewal, or inspections, so that those needing ready access do not have to climb over or remove obstacles or to resort to portable ladders, chairs, etc. (See Accessible.)
Receptacle. A receptacle is a contact device installed at the outlet for the connection of an attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is two or more contact devices on the same yoke.
Receptacle outlet. An outlet where one or more receptacles are installed.
Remote-control circuit. Any electric circuit that controls any other circuit through a relay or an equivalent device.
Sealable equipment. Equipment enclosed in a case or cabinet that is provided with a means of sealing or locking so that live parts cannot be made accessible without opening the enclosure. The equipment may or may not be operable without opening the enclosure.
Separately derived system. A premises wiring system whose power is derived from a battery, a solar photovoltaic system, or from a generator, transformer, or converter windings, and that has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.
Service. The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.
Service cable. Service conductors made up in the form of a cable.
Service conductors. The conductors from the service point to the service disconnecting means.
Service drop. The overhead service conductors from the last pole or other aerial support to and including the splices, if any, connecting to the service-entrance conductors at the building or other structure.
Service-entrance cable. Service-entrance cable is a single conductor or multiconductor assembly provided with or without an overall covering, primarily used for services, and is of the following types:
(1) Type SE. Type SE, having a flame-retardant, moisture resistant covering
(2) Type USE. Type USE, identified for underground use, having a moisture-resistant covering, but not required to have a flame-retardant covering. Cabled, single-conductor, Type USE constructions recognized for underground use may have a bare copper conductor cabled with the assembly. Type USE single, parallel, or cable conductor assemblies recognized for underground use may have a bare copper concentric conductor applied. These constructions do not require an outer overall covering.
Service-entrance conductors, overhead system. The service conductors between the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tape or splice to the service drop.
Service entrance conductors, underground system. The service conductors between the terminals of the service equipment and the point of connection to the service lateral.
Service equipment. The necessary equipment, usually consisting of one or more circuit breakers or switches and fuses, and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and cutoff of the supply.
Service point. The point of connection between the facilities of the serving utility and the premises wiring.
Shielded nonmetallic-sheathed cable. Type SNM, shielded nonmetallic-sheathed cable is a factory assembly of two or more insulated conductors in an extruded core of moisture-resistant, flame-resistant nonmetallic material, covered with an overlapping spiral metal tape and wire shield and jacketed with an extruded moisture-, flame-, oil-, corrosion-, fungus-, and sunlight-resistant nonmetallic material.
Show window. Any window used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rear and whether or not it has a platform raised higher than the street floor level.
Signaling circuit. Any electric circuit that energizes signaling equipment.
Storable swimming or wading pool. A pool that is constructed on or above the ground and is capable of holding water to a maximum depth of 1.07 m (42 in.), or a pool with nonmetallic, molded polymeric walls or inflatable fabric walls regardless of dimension.
Switchboard. A large single panel, frame, or assembly of panels on which are mounted, on the face or back, or both, switches, overcurrent and other protective devices, buses, and usually instruments. Switchboards are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets. (See Panelboard.)
Switch. (1) General-use switch. A switch intended for use ingeneral distribution and branch circuits. It is rated in amperes, and it is capable of interrupting its rated current at its rated voltage.
(2) General-use snap switch. A form of general-use switch constructed so that it can be installed in device boxes or on box covers, or otherwise used in conjunction with wiring systems recognized by this subpart.
(3) Isolating switch. A switch intended for isolating an electric circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means.
(4) Motor-circuit switch. A switch, rated in horsepower, capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage.
Switching devices. (Over 600 volts, nominal.) Devices designed to close and open one or more electric circuits. Included in this category are circuit breakers, cutouts, disconnecting (or isolating) switches, disconnecting means, interrupter switches, and oil (filled) cutouts. Transportable X-ray. X-ray equipment installed in a vehicle or that may readily be disassembled for transport in a vehicle.
Utilization equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
Utilization system. A system that provides electric power and light for employee workplaces, and includes the premises wiring system and utilization equipment.
Ventilated. Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors.
Volatile flammable liquid. A flammable liquid having a flash point below 38°C (100°F), or a flammable liquid whose temperature is above its flash point, or a Class II combustible liquid having a vapor pressure not exceeding 276 kPa (40 psia) at 38°C (100°F) and whose temperature is above its flash point.
Voltage (of a circuit). The greatest root-mean-square (rms) (effective) difference of potential between any two conductors of the circuit concerned.
Voltage, nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (as 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.
Voltage to ground. For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
Watertight. So constructed that moisture will not enter the enclosure.
Weatherproof. So constructed or protected that exposure to the weather will not interfere with successful operation. Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or temperature extremes, are not a factor.
Wireways. Wireways are sheet-metal troughs with hinged or removable covers for housing and protecting electric wires and cable and in which conductors are laid in place after the wireway has been installed as a complete system.
6. Appendix A to Subpart S of part 1910 would be revised to read as follows:
Appendix A to Subpart S of Part 1910--References for Further Information
The following references provide nonmandatory information that can be helpful in understanding and complying with Subpart S:
ANSI/API RP 500-1998 (2002) Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I Division 1 and Division 2. ANSI/API RP 505-1998 (2002) Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1 and Zone 2.
ANSI/ASME A17.1-2000 Safety Code for Elevators and Escalators. ANSI/ASME B30.2-2001 Safety Code for Overhead and Gantry Cranes.
ANSI/ASME B30.3-1996 Construction Tower Cranes.
ANSI/ASME B30.4-2003 Portal, Tower, and Pedestal Cranes.
ANSI/ASME B30.5-2000 Mobile And Locomotive Cranes.
ANSI/ASME B30.6-2003 Derricks.
ANSI/ASME B30.7-2001 Base Mounted Drum Hoists.
ANSI/ASME B30.8-2000 Floating Cranes And Floating Derricks.
ANSI/ASME B30.11-1998 Monorails And Underhung Cranes.
ANSI/ASME B30.12-2001 Handling Loads Suspended from Rotorcraft.
ANSI/ASME B30.13-2003 2003 Storage/Retrieval (S/R) Machines and Associated Equipment.
ANSI/ASME B30.15-Safety Code for Mobile Hydraulic Cranes.
ANSI/ASME B30.16-2003 Overhead Hoists (Underhung).
ANSI/IEEE C2-2002 National Electrical Safety Code.
ANSI K61.1-1999 Safety Requirements for the Storage and Handling of Anhydrous Ammonia.
ANSI/UL 913-2002 Intrinsically Safe Apparatus and Associated Apparatus for Use in Class I, II, and III, Division 1, Hazardous (Classified) Locations.
ANSI/UL 2279-1997 Electrical Equipment for Use in Class I, Zone 0, 1 and 2 Hazardous (Classified) Locations.
ASTM D3176-1989 (2002) Standard Practice for Ultimate Analysis of Coal and Coke.
ASTM D3180-1989 (2002) Standard Practice for Calculating Coal and Coke Analyses from As-Determined to Different Bases.
NFPA 20-1999 Standard for the Installation of Stationary Pumps for Fire Protection.
NFPA 30-2000 Flammable and Combustible Liquids Code.
NFPA 32-2000 Standard for Drycleaning Plants.
NFPA 33-2000 Standard for Spray Application Using Flammable or Combustible Materials.
NFPA 34-2000 Standard for Dipping and Coating Processes Using Flammable or Combustible Liquids.
NFPA 35-1999 Standard for the Manufacture of Organic Coatings.
NFPA 36-2001 Standard for Solvent Extraction Plants.
NFPA 40-2001 Standard for the Storage and Handling of Cellulose Nitrate Film.
NFPA 58-2001 Liquefied Petroleum Gas Code.
NFPA 59-2001 Utility LP-Gas Plant Code.
NFPA 70-2002 National Electrical Code.
NFPA 70E-2000 Standard for Electrical Safety Requirements for Employee Workplaces.
NFPA 77-2000 Recommended Practice on Static Electricity.
NFPA 80-1999 Standard for Fire Doors and Fire Windows.
NFPA 88A-2002 Standard for Parking Structures.
NFPA 91-1999 Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids.
NFPA 101-2003 Life Safety Code.
NFPA 496-1998 Standard for Purged and Pressurized Enclosures for Electrical Equipment.
NFPA 497-1997 Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.
NFPA 505-2002 Fire Safety Standard for Powered Industrial Trucks Including Type Designations, Areas of Use, Conversions, Maintenance, and Operation.
NMAB 353-1-1979 Matrix of Combustion-Relevant Properties and Classification of Gases, Vapors, and Selected Solids.
NMAB 353-2-1979 Test Equipment for Use in Determining Classifications of Combustible Dusts.
NMAB 353-3-1980 Classification of Combustible Dust in Accordance with the National Electrical Code.
Appendices B and C [Removed]
7. Appendices B and C to Subpart S of part 1910 would be removed.
[FR Doc. 04-7033 Filed 4-2-04; 8:45 am]
Footnote 1 See, for example, letters from: Judith Gorman, Managing Director of the Institute of Electrical and Electronic Engineers; George D. Miller, President and Chief Executive Officer of the National Fire Protection Association; Frank K. Kitzantides, Vice President of Engineering at the National Electrical Manufacturers Association; and Kari P. Barrett, Director of Regulatory and Technical Affairs, Plant Operations, at the American Chemistry Council. (Back to text)
Footnote 2 "2002 Census of Fatal Occupational Injuries," Table A-9, Bureau of Labor Statistics, http://www.bls.gov/iif/oshwc/cfoi/cftb0163.pdf. (Back to text)
Footnote 3 Overheating can also lead to electric shock hazards if the insulation protecting a conductor melts. (Back to text)
Footnote 4 Electric equipment is typically rated for use with certain voltages and current. For example, an electric hair dryer might be rated at 125 volts, 1875 watts. The voltage rating indicates the maximum voltage for which the equipment is rated. The wattage rating indicates how much power the equipment will draw when connected to a circuit at the maximum voltage. The current drawn by the equipment is the wattage rating divided by the voltage rating. Thus, the circuit voltage (120 volts, nominal) is less than the maximum rated voltage of the hair dryer (125 volts), and the circuit is rated for the current the equipment will draw (1875 watts/125 volts = 15 amperes). Thus, the hair dryer would be suitable for use on a 120-volt circuit capable of safely carrying 15 amperes. (Back to text)
Footnote 5 OSHA added electrical safety-related work practice requirements to Subpart S on August 6, 1990 (55 FR 31984). Those requirements were based on Part II of 1988 edition of NFPA 70E. However, the current rulemaking makes no changes to the safety-related work practice provisions in Subpart S. (Back to text)
Footnote 6 The Survey of Occupational Injuries and Illnesses and the Census of fatal occupational injuries, http://www.bls.gov/iif/home.htm#tables. (Back to text)
Footnote 7 This exception was incorporated into the current OSHA standard solely to be consistent with language used in the NEC and NFPA 70E. However, it should be noted that OSHA does not have jurisdiction over mines in general, regardless of whether the mining activity takes place above ground or underground. Under the Mine Safety and Health Act (MSH Act) (30 U.S.C. 801 et seq.), the Mine Safety and Health Administration (MSHA) regulates safety and health in mines. The MSH Act defines "mine" very broadly as:
(h)(1) "coal or other mine" means (A) an area of land from which minerals are extracted in nonliquid form or, if in liquid form, are extracted with workers underground, (B) private ways and roads appurtenant to such area, and (C) lands, excavations, underground passageways, shafts, slopes, tunnels and workings, structures, facilities, equipment, machines, tools, or other property including impoundments, retention dams, and tailings ponds, on the surface or underground, used in, or to be used in, or resulting from, the work of extracting such minerals from their natural deposits in nonliquid form, or if in liquid form, with workers underground, or used in, or to be used in, the milling of such minerals, or the work of preparing coal or other minerals, and includes custom coal preparation facilities. In making a determination of what constitutes mineral milling for purposes of this chapter, the Secretary shall give due consideration to the convenience of administration resulting from the delegation to one Assistant Secretary of all authority with respect to the health and safety of miners employed at one physical establishment;
(2) For purposes of subchapters II, III, and IV of this chapter, "coal mine" means an area of land and all structures, facilities, machinery, tools, equipment, shafts, slopes, tunnels, excavations, and other property, real or personal, placed upon, under, or above the surface of such land by any person, used in, or to be used in, or resulting from, the work of extracting in such area bituminous coal, lignite, or anthracite from its natural deposits in the earth by any means or method, and the work of preparing the coal so extracted, and includes custom coal preparation facilities;
For further information, see the Interagency Agreement between MSHA and OSHA (http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=MOU&p_id=222). (Back to text)
Footnote 8 Although the wiring of recreational vehicles and mobile homes is transportable, it is also designed to be attached to specially designed, permanently installed power distribution outlets. This type of hybrid system must be designed for both permanent and transportable uses. (Back to text)
Footnote 9 It should be noted that, unlike the shipyard employment standards, OSHA's construction standards have a comprehensive electrical installation standard in Subpart K of Part 1926, which covers all aspects of electrical safety that are addressed in the electrical installation standard for general industry. Thus, none of the electrical installation requirements in Subpart S of Part 1910 apply in construction. (Back to text)
Footnote 10 See the discussion under the heading "Zone Classification" for an explanation of the zone classification system and its differences from the current standard's division classification system. (Back to text)
Footnote 11 See the discussion of the term "overhaul" later in this section of the preamble. (Back to text)
Footnote 12 All of the requirements in question appear in some version in every edition of the NEC since 1972. (Back to text)
Footnote 13 These provisions have no counterpart in existing Subpart S, but were in the 1971 National Electrical Code. (Back to text)
Footnote 14 For the purposes of this discussion, "temporarily installed equipment or wiring" is wiring and equipment installed on a short-term rather than a long-term or permanent basis. It includes temporary wiring covered by proposed § 1910.305(a)(2) and other equipment and wiring similarly installed on a short-term basis. (Back to text)
Footnote 15 In the preamble to the final rule adopting a requirement for GFCIs on construction sites, OSHA estimated that there were between 30 and 45 deaths per year caused by 120-volt ground faults on construction sites, and the Agency determined that nearly all of those deaths could be prevented by the use of GFCIs or an assured grounding program (41 FR 55701). OSHA fatality investigation data indicate that only 46 deaths involving 120-volt ground-faults in temporary wiring occurred over the years 1990 to 1996 (the latest year for which data are complete). This is a death rate of only 6.6 per year. Thus, OSHA believes that the rule has saved between 24 and 39 lives per year or, over the 25 years the rule has been in effect, a total of between 600 and 975 lives. (Back to text)
Footnote 16 These accidents were investigated by OSHA generally in response to employer reports of a fatality or three or more hospitalized injuries. (Back to text)
Footnote 17 The IEC prepares and publishes international standards for all electrical, electronic and related technologies. This global organization is made up of members from more than 60 participating countries, including the U.S. (Back to text)
Footnote 18 Brenon, M., Kelly, P., McManama, K., Klausmeyer, U., Shao, W., Smith, P., "The Impact of the IECEx Scheme on the Global Availability of Explosion Protected Apparatus," Record of Conference Papers of the 1999 Petroleum and Chemical Industry Technical Conference, September 13-15, 1999, Paper No. PCIC-99-07, pp. 99-109. (Back to text)
Footnote 19 Acetylene is the only Group A gas under the division system. (Back to text)
Footnote 20 The MESG is the maximum clearance between two parallel metal surfaces that has been found, under specified test conditions, to prevent an explosion in a test chamber from being propagated to a secondary chamber containing the same gas or vapor at the same concentration. (Back to text)
Footnote 21 The MIC ratio is the ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under the same test conditions. (Back to text)
Footnote 22 As noted earlier, the zone system was first incorporated into the NEC in the 1996 edition. This edition was adopted by various governmental jurisdictions beginning in 1997. Installations made using the zone system were not permitted by these jurisdictions before then. In addition, the existing OSHA standard does not permit classifying hazardous locations under the zone system, and employers have not been certain that installations made using the zone classification systems would be acceptable to OSHA. (Back to text)
Footnote 23 Division 2 and Zone 2 are basically equivalent classifications, but there are some differences in what types of equipment are acceptable in each of those locations. See, for example, the earlier discussion on maximum allowable surface temperatures. (Back to text)
Footnote 24 Equipment that is of a type that no nationally recognized testing laboratory accepts as being safe can achieve approval through acceptance by a Federal, State, or local authority having jurisdiction over the safety of electrical installations. Custom-made equipment can gain approval through testing by the equipment manufacturer. However, these two modes of approval are rare for equipment installed in hazardous locations. Federal, State, and local authorities generally look to NRTLs for equipment approval, and this is even more true for equipment installed in hazardous locations. This type of equipment must be tested to ensure that it is safe, and these authorities generally do not have the capability to do electrical testing. Custom-made equipment, by its very nature, is very rare.
Existing § 1910.307(b) also recognizes equipment that is "safe for the hazardous (classified) location." This provision permits equipment that is approved for installation in nonhazardous locations if the employer demonstrates that the equipment will provide protection from the hazards arising from the combustibility and flammability of vapors, liquids, gases, dusts, or fibers. This condition exists only in limited circumstances as demonstrated by the 2002 NEC, which permits only certain types of general-purpose equipment in hazardous locations and then only under limited conditions. For example, Section 501.8(B) of the 2002 NEC permits nonexplosionproof enclosed motors in Class I, Division 2 locations if they have no brushes, switching mechanisms, or similar arc-producing devices and if exposed motor surfaces do not exceed 80 percent of the ignition temperature of the gas or vapor involved. (Back to text)24
Footnote 25 Except for the note to the definition, the exact language was taken from the 2002 NEC. This version is clearer than the definition in NFPA 70E, but the intent is the same. OSHA has clarified the note to indicate that acceptability of testing and inspection agencies is given in the definition of "acceptable." (Back to text)
Footnote 26 NFPA 70E uses the word "recognizable" in lieu of "approved" in the definition of "identified." It also contains a fine print note following the definition indicating that suitability of equipment for a specific purpose, environment, or application may be determined by a qualified testing laboratory, inspection agency, or other organization concerned with product evaluation. The proposed and existing OSHA standards both require all electric equipment to be approved, and this approval is the only mechanism for recognizing equipment as suitable. The Agency believes that the proposed definition of "identified" as applied to equipment clarifies the intent of the standard and is consistent with the existing standard's provisions that require electric equipment to be "approved for the purpose." (Back to text)
Footnote 27 Employers who make minor modifications to these platforms would thus be required to follow Subpart S rather than the 1971 NEC. Newer installations and major modifications of older platforms are already required to meet Subpart S with respect to the platform's electrical wiring and equipment. (Back to text)
Footnote 28 The 1996 version of the NEC preceded the 1999 version. (Back to text)
Footnote 29 In States with no mandated electrical code pertaining to new installations, OSHA's existing standards, which are primarily based on the 1971 and 1978 NECs, are the governing regulations. (In State Plan States, each State has adopted a standard that Federal OSHA has found to be at least as effective as the Federal standard. For all practical purposes, this means that OSHA's existing standard is the governing standard unless the State has adopted a more stringent standard.) (Back to text)
Footnote 30 Maryland has adopted the 1999 NEC as a Mandatory Minimum Code, exempting Baltimore from compliance. Generally when a state updates these mandatory minimum requirements, the new requirements apply only to new facilities or installations. (Back to text)
Footnote 31 Note that of these seven States, Hawaii is the only State Plan State. Hawaii has adopted the Federal standard. (Back to text)
Footnote 32 These 58 SICs include employers in maritime employment. (Back to text)
Footnote 33 Some cities within these States have adopted the 1999 (or later) NEC, and these cities were excluded when examining the accident report data. (Back to text)
Footnote 34 See EPA's Guidelines for Preparing Economic Analyses, EPA 240-R-00-003, September 2000. Note that the $6.1 million is in 1999 dollars. If this figure is updated for inflation using the CPI as EPA indicates is appropriate, the estimated 1.3 lives saved per year would translate to an annual benefit of $6.6 million to $13.2 million (in 2002 dollars). (Back to text)
Footnote 35 Data on new and other (major renovation, addition, and alteration) construction projects started annually between 1998 and 2001 are compiled by F.W. Dodge (Schriver, 2002). While construction projects serve as the basis for estimating costs, construction is not covered by the proposed standard. Rather, it is the particular product or output of the construction project that is covered. (Back to text)
Footnote 36 The wage rate data are for 2000, taken from the BLS (2001) 2000 National Occupational Employment Statistics (OES) Survey. Fringe benefit rate data are from BLS (2000) Employer Costs for Employee Compensation, March. USDL: 00-186. (Back to text)
Footnote 37 As noted previously, construction requirements imposed by mortgage lenders and insurance carriers and installation practices followed by licensed electricians (given their formal training) are reasons to expect that some employers comply NFPA 70E recommendations in the absence of any legal obligation. (Back to text)
Footnote 38 OSHA also examined the situation where all compliance costs accrue to the construction sector (in SIC 1731, Electrical Services). In this case, costs constitute 0.04 percent of revenues and 1.3 percent of profits. Thus, even if all costs are assigned to construction, the proposed regulation will not have a significant impact on small entities. (Back to text)