Snap switches, including dimmer switches, are commonly used for controlling lighting in buildings. When more than one snap switch is provided at a particular location, the plurality of snap switches are mounted on a wiring box disposed in a wall and covered by a faceplate attached to the wiring box.
Section 380-9(b) of the revised National Electrical Code currently requires that each snap switch be grounded. This section additionally requires that each snap switch provide a means for grounding a metal faceplate of the wiring box. According to this section, a snap switch is considered to be effectively grounded if the snap switch is mounted with metal screws to a metal box or to a non-metallic box having integral means for grounding devices. Alternatively, the snap switch is considered to be effectively grounded if an equipment grounding conductor or equipment bonding jumper is connected to an equipment grounding terminal of the snap switch.
To comply with the revised code when installing snap switches in a non-metallic wiring box, the current industry practice is to connect the equipment grounding terminal of each snap switch to a common ground of the wiring box using an exposed solid copper wire. The common ground typically comprises a wiring nut to which each ground wire leading into the wiring box is connected.
A drawback to this current practice for grounding snap switches is that the possibility exists that an exposed solid copper wire leading from a snap switch to the grounding nut may inadvertently contact an unsheathed portion of a hot wire or a mounting screw of the hot wire, thereby resulting in a short circuit. The risk of a short circuit occurs when the snap switch is installed in or withdrawn from a wiring box, especially since the stiffness of the solid copper wire makes it difficult to manipulate for avoiding a short circuit. Furthermore, this risk significantly increases as the number of snap switches installed in the wiring box increases.
A need therefore exists for a better method of grounding snap switches in a wiring box which minimizes the risk of a short circuit.