The electrical wiring art includes many varieties of junction boxes. These junction boxes range from the simple, rather small metal or plastic variety used with conventional Romex wire for protected inside residential wiring, to the large, complex, and specially sealed junction boxes used in wet, hazardous, or flammable industrial environments. Many such junction boxes for specialized installation circumstances also require specialized electrical cable constructions specific to the particular use. However, few uses of junction boxes for electrical wiring are more demanding than electrical installations around swimming pools.
With the proximity to water around a swimming pool, and the necessary, although limited, access by those not skilled as electricians (for example, access by a home owner or resident in order to change the light bulb in a submerged swimming pool light fixture), the electrical code requirements applying to such installations are very demanding. Particularly, the American National Standards Institute/Underwriters Laboratories, Inc., (ANSI/UL) standard for junction boxes for swimming pool light fixtures (Standard for Safety, UL 1241), includes detailed and stringent requirements relating to all of: materials of construction; environmental sealing; connections, grounding, bonding, and strain relief of wiring; voltage drop, volume, and heat dissipation; and installation integrity factors (strength of mechanical connection between conduits and the junction box, for example); all intended to insure the safety of electrical wiring to lighting fixtures at swimming pools with their environment of corrosive chlorinated water, possible impact from lawn and gardening equipment or from toys used in and around the pool, foliage, insects, vermin, pets, children, and line voltage electricity.
As an example of the construction resulting from these standards, it may be noted that the usual light fixture for a swimming pool includes a water-tight lamp fixture having a bulb socket, which is normally received into a nitch below water level in the pool, and which is connected by a length of flexible cable extending through a conduit to a junction box above water level. The junction box is usually located a short distance from the pool itself. Connecting to the lamp fixture through the flexible cable, and in addition to the "hot" wire which will be connected to the domestic power line when the light switch is on, may be a neutral wire, a ground wire, and a bonding conductor, all of which are connected to the grounding bus at the domestic line-voltage load center (breaker box) for the installation.
Thus, when a person (such as the home owner or resident) who may not be a skilled electrician, and who in fact may be somewhat careless around the pool while working to change the light bulb, removes the lamp fixture from the nitch and raises it above water level in order to change the light bulb, the bulb socket and fixture are effectively maintained at ground potential even if the switch for the light has been mistakenly left turned on. Even if one or two of the three ground-potential conductors at the bulb socket, including the ground conductor for the bulb socket, the neutral wire, or the bonding conductor, has become disconnected or broken, the home owner or resident is protected from electrical shock by the remaining one or more of these three conductors. Each of these conductors has sufficient current carrying capacity and a low enough voltage drop so that it is very unlikely that the person could be shocked or electrocuted while changing the light bulb. A current carrying path to ground of low voltage drop and high current capacity is ensured by one or more of the three grounded conductors so that the persons body is not subjected to line voltage even if the switch to the light has been left on during the bulb change. Further, additional national, regional, or municipal codes (National Electrical Code, NFPA 70, for example), may apply to a particular swimming pool light fixture installation. Thus, a multitude of differing combinations of code requirements may apply to swimming pool light fixture installations dependent on where they are located across the United States.
As a result, the electrical wiring industry has developed a very large number of standard junction boxes adapted to satisfy the generally applicable code requirements, to also satisfy the code requirements of certain locales, and to allow for a desired number of swimming pool light fixtures to be wired from the various designs of junction boxes. Some of these junction boxes are designed for use with metal conduit (brass or aluminum, for example), while others are designed for use with nonconductive polymeric conduit, such as that made from polyvinylchloride (PVC), for example, with the use of adapters or bonding bushings at the threaded conduit bosses of the junction box.
Some junction boxes for swimming pool light installations are designed to satisfy the local requirements as to conduit size, or materials and will not satisfy the requirements of other localities. Some junction boxes are even custom designed and manufactured as ordered to satisfy the combination of code requirements of particular locales and to allow the desired number of light fixtures to be wired from the junction box. That is, some locales require the use of plural junction boxes to wire a certain number of light fixtures, while another locale may allow a single standard or custom junction box to serve the same number of light fixtures. Alternatively, the expense and necessary waiting time of having a custom junction box designed and made may mitigate in favor of using plural commonly available junction boxes to satisfy the needs of a particular swimming pool light fixture installation, but at the expense of additional wiring and installation expense.
In view of the above, it is easy to understand why the wiring industry has developed plural swimming pool junction box designs, which are manufactured in plural sizes to meet varying installation needs. Of course, this variety in junction box designs and sizes means a great burden in junction box inventory for manufacturers and distributors, in installation logistics for swimming pool installation and service contractors in order to insure that the right junction box design and size is available and is used at a certain job, and for local building inspectors in the inspection of wiring installations because of the multitude of codes applicable to each particular installation, and the great variety of junction boxes which are available and which may or may not satisfy the mosaic of different code requirements for each installation.
It is easy to understand that there is a considerable challenge for the contractor and inspector in determining whether the junction boxes actually used out of the multitude of boxes available do, in fact, satisfy the many applicable code requirements at a job site. Of course, all of this leads to a resulting increase in the chances for error and disagreement between planners, installers, and inspectors, with resulting rework of wiring installations and loss of time and productivity.
In addition to the confusing variety of designs, sizes, and materials of swimming pool junction boxes, several available junction boxes have unfortunate features which make their use difficult in particular situations. For example, a particular box may limit installation flexibility because of its shape. That is, a rectangular junction box installed next to a wall may suggest that the length of the box be parallel to the wall. However, such installation requires that the electrical conduits to be connected to the box all be lined up parallel to the wall and spaced therefrom according to the positions of the conduit hubs or bosses of the junction box. On the other hand, the junction box by its design may require the installer or electrician to have access from the side of the box which is adjacent the wall.
That is, installation of the junction box, or connection of wiring therein, may necessitate horizontal access either manually or with tools into the junction box. Accordingly, while the home owner may prefer that the junction box be placed parallel to an adjacent house wall or fence, the electrician may require that the box be placed perpendicular to the wall or fence in order to complete the wiring installation. Thus, yet another limitation, that of access for wiring installation and service, is encountered with conventional junction boxes for swimming pool light fixtures when actual installation events and use environments are considered.
Additionally, conventional junction boxes when used with metallic conduit require that the box be threaded onto the threaded ends of the conduits, either directly or by the use of couplers. For a box with plural conduit bosses, only one of the conduits can be threadably connected directly with the junction box by relative rotation of the box at installation. Connection of all of the other conduits will require use of a coupler which is threaded into the threaded boss of the junction box. These couplers add complexity and expense to the installation of the junction box. Also, these couplers add additional leakage paths through which moisture may enter the junction box.
Similarly, when PVC conduit is used with conventional junction boxes, the junction box cannot be bonded directly to the plastic conduits. Accordingly, bonding adapters or bushings which thread into the threaded bosses of the junction box and include a captive PVC sleeve to which the plastic conduit can be bonded must be used. These bonding adapters simply slip onto the ends of the plastic conduit so that the requirement to rotate the junction box for threading engagement with a conduit is removed. Also, threading couplers, as are used with metallic conduit, are not required. However, the bonding adapters themselves add considerably to the expense and complexity of the installation. Also, these bonding adapters create additional leakage paths through which moisture may enter the junction box.
All of these limitations of conventional junction boxes for swimming pool light fixtures are known all too well to those working in the industry. However, prior to the present invention, no junction box gave significant relief to the plural deficiencies, and resulting long-felt need for improvements, as outlined above.