Looking for clarity on Sec. 250.122 grounding conductor size:

[herding_cats]

This issue came up in a different thread on subpanel grounding and one of my guys getting harassed by local inspection on the conductor. According to Sec. 250.122, you can use #12 THHN copper as the GEC up to the point of 60A service. One member had commented that a 30A service with a #12 GEC was illegal. Which is correct?

 

[wwhitney]

250.122 is for sizing EGCs, not GECs. GECs are sized per 250.66.

Also, #12 Cu is the EGC size for 20A circuits. 25-60A circuits require a #10 Cu EGC.

Cheers, Wayne

 

[roger]

One member had commented that a 30A service with a #12 GEC was illegal. Which is correct?

I think you might be looking for 250.66

 

[herding_cats]

So 250.122 is referring to the neutral conductor, not the GEC?

 

[roger]

So 250.122 is referring to the neutral conductor, not the GEC?

250.122 is for the EGC

 

[herding_cats]

I think you might be looking for 250.66

right

 

[ActionDave]

That was me. We were dicussing Equipment Grounding Conductors, not Grounding Electrode Conductors, transposed letters not withstanding. I went and looked it up and you are correct about table 250.122. I was mis-remembering about a 30A circuit. But you also mentioned that the inspector said you couldn't use a bare wire for an EGC. The inspector was wrong about that. 250.118 clearly says "insulated, covered, or bare" when referencing what kinds of conductors can be used for an EGC.

 

[herding_cats]

Exactly. 250.122 and 250.66 a bit confusing. Thanks everyone for the clarifications. The inspector didn't know what he was talking about. If you know anything about Wyandotte County Kansas it's like a third world country. The "inspector" might be a school shop teacher off for the summer. It works like that here.

 

[ActionDave]

Wait. New evidence has been admitted in the other thread. I was right about needing 10AWG for a 30A circuit. 12AWG is only good up to a 25A. Sure glad I spend all that money on continuing ed classes (sarcasm).