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I found this box: box with 2 ground clips

You can see that most of the conductors have their grounds crimped together in the deep part of the box.

A box extension was added to this at some point, so it is rather deep, but then I noticed that one of the conductors has a second ground clip to the box extension, and that is how the ground connection to the rest of the grounds is currently being made. To be clear, the singled-out ground wire is a load, not the line conductor here.

Is this an acceptable technique when I replace that one conductor so I can do the same thing the last guy apparently did -- ie. avoid cutting those other grounds by clipping to the box?

I need to replace the conductor with the separated ground wire on the right side of the photo because it is 14 gauge on a 20-amp circuit and needs to be replaced with a 12 gauge because I am redoing the wiring downstream. The other wires are all 12 gauge. If I don't have to cut those grounds apart that are all crimped that would be best because the other conductors don't have enough service slack to pull them in further after cutting the grounds which would greatly expand the scope of work here.

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  • I already understand that even if this is allowed it isn't ideal, but the reason I am asking is it is a matter of remediating an old-work issue I did not cause. Feb 25 at 2:10
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    Side question: do you need a 20A breaker? If you could live with a 15A, all your wiring would be legal. Feb 25 at 5:19
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    @AloysiusDefenestrate you know, I didn't stop to consider that. You're right, that would work because the circuit is 5 lights and 3 receptacles, which meets the guideline of 8 outlets on a 15A circuit, 2 of which are exterior receptacles with 15 amp sockets. However, since the only thing preventing this circuit from being all 12 gauge wire is 4-feet of Romex, I think it is worth it. I might decide to make those exterior receptacles 20A GFIs once I upgrade them in case I need serious power outside. Another perk is two more outlets can piggy-back off of it if needed in the future. Feb 25 at 5:30

2 Answers 2

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This is fine

NEC 250.109 explicitly permits metal boxes to be part of the ground-fault current path:

Metal enclosures shall be permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path. If installed, metal covers, plaster rings, extension rings, and metal fittings shall be attached to these metal enclosures to ensure an effective ground-fault current path or shall be connected with bonding jumpers or equipment grounding conductors, or both.

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ThreePhaseEel clicked Post before me, but here's what I was working on...

Metal extension rings are self-grounding when installed properly. They are treated as part of the box. As long as you re-attach the new wire, it's going to be legal. NEC 250.148 says the ground wires "shall be connected within the box or to the box" and paragraph C says a connection shall be made to the box. There's nothing to limit the number of connections.

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