I was recently installing a light switch in metal conduit. I noticed that it had a green screw for grounding. Does it really need it? If so why?
If any device has a ground screw, use it. Why? Because that's what the NEC says you have to do. As an aside, here in Canada none of our residential grade switches have ground screws. Why? Because the CEC says we don't need them.
The switch is grounded to preclude the switch plate from being electrified. As BB1 says, if you've got a ground, ground it. There's an exception if you don't have a ground where you can use a nonconductive face plate, but what's the point.
NEC Articles 404.9(B) and 404.12 might apply in this particular situation.
because if you dont and you just got out of the tub and sumhow the plate got electrified and you touch it you will become the ground and the will find you naked on the floor covered in crap.
Green, metal conduit (and metal device box? reckon so) provide the ground-path, but that ain't the same as grounding the device.
Now then, I don't want to p*ss with anybody, but I've an objection to answering questions with, "'Cause Mama says." Call me crazy, but I believe NEC and CEC both have sound reasons for what they say - well, for the most part.
Well tell me pudge, how about all those houses wired without grounds? Are all of those plastic plates some how going to be mysticly electrified?
texas not necisarily the whole plate but the screws that hold the plat on I am still on votech and this is what my techer told us the other day when a kid asked this very same question.
It is extremly remote that anyone would receive a shock on the screws on a plastic switch cover and the switch not being grounded further has nothing to do with it.
What can happen is one of the side screws on a switch or receptacle come in contact with the side of a metal box especially if it is one of the old smaller boxes. In these cases I put electrical tape around the fixture.
It depends on how much you value your life and if your insurance policy is in force. They are there for only one reason, your safety. I ALWAYS CONNECT them!
As far as the side screws touching the metal box, that won't happen unless something is wrong. The wiring device is designed to prevent that.
Mr. Gilshultz, I have no idea about what you are talking. You get 3 or 4 switches in a box, I tape them so the leads don't touch each other. Tell us how the wiring device is designed to prevent-what?
When the (switch plug etc) is mounted in the box and properly wired it will not allow a wire to connected to a screw to contact the box. When you remove the mounting screw that no longer applies.