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2 circuits in EMT with one using wire as ground #220125 07/07/19 12:14 PM
Joined: Jul 2019
Posts: 1
U
UTEE87 Offline OP
New Member
I’m wiring a metal building with EMT raceway and THHN conductors. It’s a detached building with a 100amp “sub panel” fed from the nearby house. One branch of the EMT carries two circuits (one lighting and one RV outlet). The lighting circuit has a 12 AWG equipment ground running to all lights and connected to 3 J boxes. The RV circuit uses the EMT raceway for equipment ground. The inspector said everything has to be one way or the other. So no mixing of ground types. I can’t find any code section that agrees or disagrees with him. I’m going to just pull all the equipment ground wire out and use the raceway as the easiest solution but I would like to know if anyone can point me to something that supports his assertion. I didn’t wire it this way but I’m finishing it.

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Re: 2 circuits in EMT with one using wire as ground [Re: UTEE87] #220126 07/07/19 08:14 PM
Joined: Jul 2004
Posts: 9,408
G
gfretwell Offline
Member
I don't know how he came up with that.
I read 250.118 I see "a combination of the following", implying you can use any of these in combination. Maybe he is looking at something else. I suppose the option is to hook a #8 to that #12 and pull it through satisfying the 100a circuit and also covering the smaller one but I don't think it is necessary by the code I use.

Quote
250.118 Types of Equipment Grounding Conductors. The
equipment grounding conductor run with or enclosing the
circuit conductors shall be one or more or a combination of
the following:
(1) A copper, aluminum, or copper-clad aluminum conductor.
This conductor shall be solid or stranded; insulated,
covered, or bare; and in the form of a wire or a busbar of
any shape.
(2) Rigid metal conduit.
(3) Intermediate metal conduit.
(4) Electrical metallic tubing.
(5) Listed flexible metal conduit


Greg Fretwell
Re: 2 circuits in EMT with one using wire as ground [Re: UTEE87] #220127 07/08/19 09:54 AM
Joined: May 2005
Posts: 984
G
ghost307 Offline
Member
I agree with Greg but I think you might be up against the old adage that you can't fight city hall.

Inspectors enforcing things that aren't in the Code isn't uncommon, but Inspectors that admit they're wrong are hard to find...except for those with class who are always the first to admit their errors.


Ghost307
Re: 2 circuits in EMT with one using wire as ground [Re: UTEE87] #220130 07/10/19 06:04 AM
Joined: Jul 2002
Posts: 8,262
Trumpy Offline
Member
Originally Posted by UTEE87
The inspector said everything has to be one way or the other.

I'm going to go out on a limb here and say that maybe the Inspector is right.
Even though it is EMT, I would still run a separate ground conductor, just to satisfy actual resistance values.

Re: 2 circuits in EMT with one using wire as ground [Re: UTEE87] #220131 07/10/19 06:33 PM
Joined: Jul 2004
Posts: 9,408
G
gfretwell Offline
Member
The issue seems to be does the supplemental green wire ground need to satisfy 250.122 even though the EMT itself already does.
It does occur to me he can shut the inspector down if he installs an IG receptacle on the 120/20a circuit connected to the green wire. (In a plastic box)


Greg Fretwell

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