The GFCI (given proper marking of the downstream receptacles) make the use of those three prong receptacles with no legitimate ground connection legal.

In addition the ground wire, provided it goes back to the panel (or the grounding electrode system) is also Ok to ground these circuit extension. I assume you have verified it goes back to the main ground bar in the service panel (you just said box without qualifying it). It can't just go to some random water pipe or other circuit box.

Ack, I knew I'd forget some detail! The wire does go back to the actual bus bar in the main (only) panel. Further, nothing is doubled up in there, it's a brand-new install. The electrician pointed this wire out to me, said he saw a ground wire going *somewhere* but couldn't tell where - I'm the one who figured out where it went, and he then verified at a later time that it was the same wire. We really just can't figure out why they only ran ground, and didn't just run a whole new wire up there at the same time when they probably had the walls open.

I know the GFCI's are OK by code to install on K&T for 3-prong if they're labeled no equipment ground - we're doing that in selected locations throughout the house for just that purpose - but what I'm wondering is if the actual extension of the circuit is okay, or am I absolutely positively supposed to run a new wire all the way back? I know a lot of people advocate that, but the way I'm reading the Code, I don't think that's neccessary - only the ground wire seems to be required to extend the circuit out legally. Or do I even need that, so long as I'm using only GFCI's?

Yes, since the wire goes back to a permitted ground (the panel), then you can use it to ground extensions to ungrounded circuits. The applicable part of the NEC is 250.130(C):
The equipment grounding conductor of a grounding type receptacle or branch circuit extension shall be permitted to be connected to any of the following ... (3) The equipment grounding terminal bar within the enclosure where the branch circuit originates.

Note the "OR" in that statement. You can use that wire to ground the single receptacle (what you have now) OR your extension (what you intend to do).

Okay, great - hmm, I am wondering why it can't be used to ground both outlets, though. I'm reading that sentence as "a ground wire coming from (these sources) is permitted to be grounded to (the ground bar in the main panel). That is, I thought 250.130(c) primarily dealt with where it's OK to ground to, ie, the whole grounding-to-a-water-pipe debate that I don't want to get into, but you know what I mean.

Certainly, if I was installing an all-new circuit, that's how I'd do it - pigtail into each outlet - so I'm not 100% sure why that's not OK here?

It's fine if it really isn't okay - I'm only REALLY going to be using one of these outlets, but since they're so close and it would be so easy to connect both outlets to this ground wire, it's tempting, for future flexibility. Definitely since I don't think we have any real means of getting a new ground wire up to the second floor, at least until we maybe gut the bathroom! :)

I'm going to go ahead and drill my holes in the studs and knock out the spot for the outlet, at least. It's exciting to get some progress!

It can be used for both. The or is inclusive.

You can go to an existing circuit which is only a two-wire, non-grounded circuit, and add a receptacle to it with 12-2 with ground, coming from the load side of a GFCI, and consider it legally grounded. The GFCI does simulate the effect of a ground (even with NO ground wire run to the panel as in your own situation), and may feed to three-prong grounded outlets with 12-2 with ground. Adding outlets to the circuit is contingent only upon the load demand of the circuit, and if you know you are not exceeding 16 amps on a 20-amp circuit with lighting or some other continuous load, you may always add on to an existing circuit. No problem - go ahead in good health.

David Moore
Electric Medic
Oak Ridge and Knoxville, TN
http://electricmedic-tn.com

Extending a non-grounded circuit using 12/2 with ground by attaching to the load side of a GFCI does NOT make it a grounded circuit nor does it simulate a ground. You may use grounded receptacles on such an extension, but they must be labeled as "No Equipment Ground" and the grounding conductor must NOT be attached to the GFCI or downstream receptacles. See NEC 406.3 (D)(3) (b&c).

Normel is right.

However, the original poster has a ground wire run to feed the ground terminal on the circuit extension. He can use that to provide the ground (and intends to). Whether he choses to use the GFCI or not is purely up to him at this point. No receptacle labelling is required in this case.

Yeah, I'm actually just about finished with this install - all that's left is to replace the drywall in the access space. Good to know that we're safe and legal!

Question, though: Why is it that a normal 3-prong outlet is OK to run off a GFCI load-side even in the absence of ground?

I understand it's functionally equivalent to just installing a GFCI there, but those little stickers may fall off over time, etc! Just seems so likely to confuse someone down the road, even though it's code legal. They could certainly assume there's an equipment ground there when there isn't, even though a person would (if all works as designed) be protected by the GFCI earlier in the circuit.

I've wondered the same thing. I had some work done on one of my rental houses a while back, GFIs putin the kitchen where the old wiring wasn't grounded. Stickers went on the downstream recepts. Tenants moved out last summer and when I went in to inspect I noticed that they'd peeled the "GFI Protected, No Equipment Ground" labels off all the recepts.

Maybe one day the code will require cover plates with that text embossed on them.

Because as far as life safety is concerned the GFCI does as good (or not better) than what the equipment ground provides in that case. It sucks for things that really wanted a ground (like a surge strip but the code doesn't much care about that).

"It sucks for things that really wanted a ground (like a surge strip but the code doesn't much care about that)."

And some surge strips actually 'leak' enough current to trip a GFCI.

> And some surge strips actually 'leak' enough current to trip a GFCI.
Then they need to be replaced. Nothing in the surge strip should cause a ground fault. If the MOV is leaking, it's probably not protecting either.