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I am remodeling a house and the partially unfinished attic has old ungrounded, 2 wire wiring. There are 2 circuits. There is a finished bedroom with one circuit on 3 walls, and a second on the 4th wall. The 2nd circuit extends out into a hallway area and then stops. I want to extend that wiring into the other side of the attic to make another bedroom and I want it grounded. I already fished a ground wire from the fuse box up to the end of the line on the 2nd circuit. (I cannot get it to the beginning of the line as there is a chimney and shed roof and a whole bunch of ugly over there).

My question is multipart. Can I start the ground there, or do I have to go back and ground the previous outlets on the circuit ? (it is wood paneling, not drywall in the room, so I could take it off, albeit a big pain in the arse) And can I try to use the same ground on the outlets of the first circuit? Do they have to be in a specific order? Can I extend multiple grounds from one junction box? I know I can use a GFCI at the beginning of the first circuit. But as I understand it, I cannot use them before the ground wire on the second.

Sorry, this question sounds about as confused as I am right now. Believe it or not, I rewired 2 houses. But I gutted them to the studs, so it was easy. And I passed inspections.

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You are asking about the rules for ground retrofit, which were greatly eased in 2014. We discuss that here and there on the site.

To answer your questions,

You can start the ground any old place. There's no requirement that the ground parallel the supply conductors.

Grounds for one circuit can be extended to protect another circuit, provided both circuits come out of the same service panel. That's only an issue if your house has subpanels. The only restriction is that the ground wire must be large enough for the circuit all the way home. So for instance if you are retrofitting a 12 AWG circuit, you can bring it to the water heater and its 10AWG ground wire. Then you can retrofit a #14 circuit and bring it to the #12. The reverse is not allowed, a #14 ground wire can't be part of the grounding path for a #12 circuit.

Order does not matter, do it any which way you can. Several circuits can share ground: Remember, grounds never flow current except during a ground fault.

GFCI protection has absolutely nothing to do with the grounds. GFCI's don't use ground at all, and have no access to ground. (Well, GFCI receptacles do, but only to supply the ground pin on the sockets; the GFCI device doesn't even connect to ground.) There shouldn't be any neutral-ground connections on the downline wiring; that would be the very definition of a ground fault.

That means that GFCI protection and ground retrofits are orthogonal; they have nothing to do with each other and can be done independently of each other.

  • @SusieIrwin sure, that works. Or you could put the GFCI in outlet #1, bring ground to outlet #3 then on to 4 and 5, leaving 1 and 2 ungrounded, then put an isolated ground on outlet #6 for your audio studio. My point is, GFCI really doesn't care what you do with grounds. Current flows in loops. It only looks at normal current paths (hot(s) and neutral): If the outbound current does not equal the returning current, it will trip. – Harper - Reinstate Monica Oct 30 '18 at 17:17
  • "There shouldn't be any neutral-ground connections on the downline wiring; that would be the very definition of a ground fault." >>> So on the 2nd circuit, I can NOT use a GFCI on the first outlet and then connect ground to the last outlet to extend the circuit? – Susie Irwin Oct 30 '18 at 17:19
  • sorry new to this. I re-read your comment, then thought I was wrong and deleted my first coment. On the 2nd circuit I will GFCI the first outlet, then run a ground wire to the last as I wrote in my deleted comment. – Susie Irwin Oct 30 '18 at 17:22
  • By "neutral-ground connections" I mean things that connect neutral and ground to each other electrically. While you do in fact connect neutral and ground to receptacles, the receptacle keeps them fully separated (isolated) and simply passes them on to plugged-in devices. The device may have a problem; so might a hardwired load such as a bathroom fan. – Harper - Reinstate Monica Oct 30 '18 at 17:28
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I suggest you to protect all the 2-wires circuit putting a GFCI outlet on the first ground of the 2-wires circuit (or just replacing the circuit breaker with a GFCI one). Doing so you'll have better protection over ground fault (low current won't trip the MCB) and you don't have to pull ground wire. Anyway, according to NEC, is not required that ground wire make same path as circuit, so yes: you can start from a single box in the middle of the line with multiple ground wires. Only thing is that all outlets not connected should be protected by GFCI.

  • The extension of the circuit needs to be grounded , as I read NEC 250.130 & 406 the extensions need to be made to current code but code now allows a ground to be run seperatly as long as connecting to the same panel the circuit originates in or another branch circuit ground that originates in the same panel or last on the main grounding electrode system. – Ed Beal Oct 30 '18 at 14:30

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