Does a three way electrical light switch need a ground?

Answer 1

Answer for USA, Canada and countries running a 60 Hertz supply service.

No, a three way electrical light switch, and for that matter any light switch, does not need a ground connected to it, in fact there is no ground screw on the switch to connect to. The box that the switch is installed in, under code, needs to be grounded by the ground wire that is in the incoming feeder cable. The ground to the switch frame is picked up from the grounded box when the switch is screwed into the light switch junction box.

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If you use the ground for a traveler your light will not be in code.


Yes, it needs a ground. You will need to use 3-wire cable. The "3" wires isn't counting the ground wire. 3-wire cable actually has four wires: Black, white, red, and ground (bare). The black and red wires are used as "travellers", and the white wire is "neutral". Never use the bare wire as a traveller, or even as the neutral wire. Though this will technically work, there are two problems: 1) you will no longer have sufficient grounding on this circuit, and someone could get a serious shock, and 2) you will have an uninsulated wire carrying current, which is a fire hazard.

Of course, if you are replacing a regular on-off switch with a 3-way, in an existing-construction situation, it is going to be very difficult to replace the wiring. But if that's the case, this is just the beginning of your trouble. See, you still have to mount the OTHER 3-way switch somewhere, and run wire to it. So even if you didn't have to replace the 2-wire cable, you still have more wire to run in already-existing walls.

Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized

IF YOU ARE NOT REALLY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.