Electrical box ground wiring.

If you live in an urban area with all-metal water distribution pipes this can be masked somewhat. If you have an open service neutral the neutral return path can become service panel neutral to the N-G bond, to the water service pipe (earthing electrode), to adjacent houses through the metal water distribution system, through their N-G service bonds, and back to the transformer through the service neutral at those houses.

There was a thread where someone had significant current on the conductor to the earthing electrodes and it turned out either he, or a neighbor, had an open service neutral.

I have seen other people say the same thing.

High current should trip the breaker.

If you had a really long circuit you could possibly come up with a 20V drop. A competent electrician would increase the wire size for really long circuits.

The NEC recommends, but does not require, 5%.

David:

You have an old box. Note the bare copper wires under the strain reliefs. You need to dig them out.

These

They are a bit difficult to attach, but The secure a solid pigtail to the side of the box. e.g. the edge that's exposed.

What I use in this case is an ground Ideal Term-a-nut. See

So, you can dig out the bare ground. Install the term-a-nut and a solid pigtail. The solid pigtail goes to the ground clip and the free end of the term-a-nut (fork terminal goes to the green screw on the outlet),

With multiple GFCI's you would want to not series the GFCI. e.g. One GFCI protects the outlets down stream.

What can cause nuisance tripping is shared neutrals. The term is shared, but think of it as neutrals attached as "T-splices"

GFCI's do not need a ground, but if they don;t have one, they must be labeled that there is no ground.

You are not supposed to rely on the screw connection from the box to to the outlet, although some outlets are designed so it's OK.

Your house looks like it had original had two prong outlets and the upgrade wasn't done correctly. The conversion can be a pain, but the term-a-nuts make the job much easier.

When there is a threaded hole in the box that can accept a ground screw, then other ways are possible.

So far, I've never tapped a ground hole.

I generally like the Term-a-nut process for wiring. One white, one black and one green. The parallel connections don't rely on the screw terminal pigtails.

Seasoned electricians pigtail the connections in the box with a wirnut.

The term-a-nuts I think can be purchased in stranded or solid. Not sure though. I use the stranded type.

Hi Ron,

I put a screw into the box and ran a wire from the screw to the GFCI's ground. But first I checked the line voltage with the neutral wire on the neutral side of the plug with a hair dryer running. Then I exchanged the neutral wire with the new ground wire and checked the voltage again with the hair dryer running. The voltages were exactly the same. That proved to me that the ground wire is making a good connection back to the service panel. Do you see an alternate explanation that would disprove my conclusion?

Thanks for your reply.

Are they legal in every jurisdiction? A lot of things aren't allowed under local codes.

I can buy them locally at a real electrical supply house, so I would suppose they are legal in mine. They are not much different than a wire nut.

I have to ask. How the hell do you attach or use those things?

Maybe you can explain this one-

A friend's apt has a ceiling fan in a room that trips the GFCI in the bathroom if you exercise the fan speed or light switch fast enough. They're on separate circuits as far as I can tell, but the wiring is old and crappy to start with so I'm not even going to take off some covers to look around.

I still have no idea how this happens. Anybody seen un-connected devices trip a GFCI outlet?

Well, technically, a GFCI device doesn't need a ground prong or a ground to function. Notice I say GCFI devive, not receptacle. Take for instance hair dryers or electric blankets these days. They have a GFCI module in the plug, which is polarized, but not grounded.

On the other hand, if you're installing a GFCI outlet, they all have ground prongs, and to not ground it would be improper. Downstream outlets could be old receptacles with no ground prong, if you're doing some sort of retrofit or hacky upgrade. I have no doubt both have been done by people at home, but a real electrician would do the same might be a different story. Anybody know what the NEC says about this?

Ummm... as I pointed out a week or so ago, the Consumer Products Safety Commission *specifically* points out that you can use a GFCI receptacle on a circuit which has no ground. It will protect its own jacks, and any other outlets which are wired "downstream", against ground faults.

This is an accepted and approved method for adding safety to a two-wire circuit which has no ground wire accessible.

I agree, it's not as good a solution as re-wiring with a good ground... but it's a lot better than leaving a two-wire circuit without ground-fault protection!

The CPSC (and I believe the NEC) requires that any GFCI outlets which don't have an actual ground, must be installed with a sticker which says so, so that the user is aware that the ground prong is "open".

The NEC requires the protected outlets be marked as non grounded. The labels come with the GFCI.

Ok- that would make sense- as stupid as a sticker may be, you need something to indicate an abnormal condition. I've only see the industrial versions of these warning tags though- never seen one screwed into a wall in an old bathtoom, at least yet.

Trivial addition - downstream receptacles also need the "GFCI protected" label.

As I think you have written, the NEC explicitly allows a (grounded) GFCI receptacle to be used on an ungrounded circuit, and allows grounded receptacles downstream, all with the label in your post. When used this way, ground terminals are not to be connected together. Ungrounded receptacles can also be used downstream.

The ground terminal on a GFCI connects only to the ground contacts for what is plugged-in. There is no connection to the protection circuit.

============================== A few changes from the 2011 NEC

If you are replacing a receptacle where it is now required to be tamper resistant (child proof), the replacement has to now be tamper resistant (most of a house).

Same with weather-resistant.

If you are extending an existing circuit in an area where AFCI protection is now required, the entire extension is required to be AFCI protected. (AFCI receptacles are now available.)

If you are replacing an ordinary receptacle in an area where GFCI protection is now required, the new receptacle is required to be GFCI protected. (Several ways to do it.)

If you are replacing an ordinary receptacle in an area where AFCI protection is now required, the new receptacle is required to be AFCI protected. (Also several ways to do it.) (Other than this, AFCI is intended to protect the branch circuit wiring in addition to the receptacle and what is plugged in.)