Grounding Switches

Maybe a code thing up here.

dglass4321 said:

We started a refresh of our 22 year old kitchen. We are having the cabinets refinished, new appliances, LED lighting and new flooring. I'm replacing the old white outlets and switches with black ones to compliment the granite. I'm finding that all the new switches have a ground screw. Why is this necessary? I understand about grounding outlets but why switches? It seems like it is unnecessary since a switch isn't a complete circuit.

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Because you could have a problem with the switch that made the steel frame of the switch live so when you touch the cover plate screw you get 120 volts.
If the switch is grounded. the breaker would pop at the first site of a problem.

nealtw said:

Because you could have a problem with the switch that made the steel frame of the switch live so when you touch the cover plate screw you get 120 volts.
If the switch is grounded. the breaker would pop at the first site of a problem.

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That’s what I said in #12.

I haven’t taken a switch apart in many years but I doubt there is a failure mode that would energize the frame of the switch. Your 120V electric drill doesn’t even have a ground as they call it double insulated.

I have a few old switches laying around I will have to pry one open and see if any failure mode could cause a frame to go hot.

nealtw said:

House 22 years old, has a ground.

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I didn't say the house wasn't grounded, if you read my post I said the switches weren't grounded. All of the outlets and fixtures are properly grounded.

slownsteady said:

q1: so 22 years ago, you installed plastic boxes?
q2: is there a bare ground wire in the wire runs (white, black, bare or green)?

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We had a contractor do the rough in of the electrical. Yes, he used plastic boxes (and no, they don't have a grounding straps) I did all the finish wiring and installed the fixtures. What we have is one black wiring coming in to the box and one black wire exiting the box. In some cases there are additional wires to accommodate three way and four way switches. If there was a bare ground wire, as there is in the outlet boxes, this would be a non issue because I would have something to ground to.

bud16415 said:

That’s what I said in #12.

I haven’t taken a switch apart in many years but I doubt there is a failure mode that would energize the frame of the switch. Your 120V electric drill doesn’t even have a ground as they call it double insulated.

I have a few old switches laying around I will have to pry one open and see if any failure mode could cause a frame to go hot.

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I was just stating why the ground is there not the probability of failure.

dglass4321 said:

I didn't say the house wasn't grounded, if you read my post I said the switches weren't grounded. All of the outlets and fixtures are properly grounded.

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Yeah I get it, just stuff I have never seen.:rofl:

Long time ago when I took my electrical classes I read something about the fact that if switches had "metal" face plates the switches must be grounded. But nowadays very few people use metal face plates in their homes.

I would not consider this to be a big safety factor at this point. Although it is possible to get a "zap" from the small screw head on the face plate even if the face plate is plastic.

You know the good-old NEC; it was developed mainly from safety/non safety incidents that have happened in the field in the past and then precautions are written into the code when they feel it is time to to prevent the accidents that have occured in the past.

The code is written to provide an installation which is "essentially free from hazard."

90.1 Purpose.
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

If the box is metal then you can ignore the ground screw on the switches strap or yoke. If the box is non metallic and there is an Equipment Grounding Conductor (EGC) available in the box the green screw with the hexagonal head provides a place to bond the EGC to the strap or yoke of the switch. If the strap or yoke of the switch is connected to ground then the use of a metal cover plate; either now or in the future; will not expose the occupant to the possibility of contact with a surface which has been energized to 120 volts to ground.