Electric wiring grounding question

Paul Janke · Mar 6, 2011

The building in question is wired with metal conduit. There is a ground wire run to every box in which there is an electrical connection. All of the ground wires are tied to the box in which they terminate, as are the continuing ground wires. All of the outlets are also grounded by wire to the boxes they are in. The question is, do the switches need a ground wire, or is it sufficient that they are screwed to the metal boxes in which they are mounted? Thanks for any help you can furnish.

Bob Bancroft · Mar 6, 2011

It will be interesting to see where this type of question goes, as usual!
Some decades ago, my advising electrician, indicated ground wires in metal conduit were redundant.

Janicholson · Mar 6, 2011

If the switches have a green ground terminal on them, they need a green jumper to the box from that screw and the green of the supply wires. The jumpers are available at nearly every big box building and supply. They will also have a green (usually) sheet metal clip that can be used to ground to the box metal if screwing is not obvious. Some inspectors will let them go if not separately grounded to the box, some won't, jurisdictions are often different. Jim

Anonymous-0 · Mar 6, 2011

ret. 42yrs elec. just think of it this way. if you have a load on the outlet and for some reason you undue the condut you have one hand on one pipe and one hand on the other the path is through you now............ you are a gonner now. DON't do IT

Paul Janke · Mar 6, 2011

I think I need to explain slightly more. The box is grounded with green wire. This would be for whether or not I need ground wires from the box ground wire to the switches mounted in that metal box.

buickanddeere · Mar 6, 2011

Metal conduit and/or the outside metal sheath of cables IS NOT a ground conductor.
Your expert needs to read the code book.

Bob Bancroft · Mar 6, 2011

My "expert", long since retired, is probably only reading sun drenched and sand covered golf scores and associated things.
Could it be that 25 years ago and across the border the rules were different?

Leroy · Mar 6, 2011

evilboweivel · Mar 6, 2011

to be safe YES

Ron

Ultradog MN · Mar 6, 2011

Used to be you only needed to ground switches in damp locations - Kitchen, bath, garage, etc.
As per about 8 years ago all switches have to be grounded.
You do not have to pull a ground through conduit.

MarkB_MI · Mar 7, 2011

I assume you're using "grounding" switches. You'll notice that one of the mounting screw holes has a piece of metal in it that rubs against the screw to ensure a good electrical bond between the switch and box. So as long as the switch is mounted in the box it should be grounded OK. Now I wouldn't be surprised if the latest NEC requires a separate ground wire, but I didn't use one in my shop when I wired it several years ago. I did run redundant ground wires through the conduit as you describe.

Anonymous-0 · Mar 7, 2011

I have heard this a number of times, but my understanding of NEC 250.118 is that it is specifically approved to used EMT, rigid, or IMT as the ground conductor.

buickanddeere · Mar 8, 2011

Ontario Eelectrical Code 23rd edition. Section 10-804. Paragraphs A through G.
To paraphrase.It says you run a ground wire in all rigid and emt conduit. Conduit is bonding, not grounding. The sheath of amoured and flex conduit is not a ground conductor. The outer copper or aluminum sheath of mineral insulated cable is not a ground if buried or exposed to corrosion.

Electric wiring grounding question

Paul Janke

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Bob Bancroft

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Janicholson

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Anonymous-0

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Paul Janke

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buickanddeere

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Bob Bancroft

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Leroy

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evilboweivel

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Ultradog MN

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MarkB_MI

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Anonymous-0

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buickanddeere

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