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My house was built in 1958. City inspector asked me to replace outlet in bathroom and kitchen with a GFCI, and says he will check if the wiring is correct or not. When I connect the GFCI, there are two problems

  1. GFCI outlet is bigger than old one, can't fit.
  2. GFCI outlet has grounding screw, but wire from box has no grounding wire.

My questions

  1. Should I cut wall to change a bigger box to fit gfci outlet.
  2. Just connect it without grounding is OK?
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    You might also consider swapping out the circuit breaker for the entire circuit to GFCI. Sometimes it’s the “best” method when dealing with old wiring and smaller junction boxes. – Tyson Nov 12 '17 at 17:53
  • Original poster, does your structure have metal boxes that are grounded? – Jim Stewart Nov 13 '17 at 17:58
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Several ways to solve this.

First, actual GFCI protection does not require a ground wire. It's better to have both GFCI and ground. But GFCI alone is still highly useful. For instance, GFCI is much better at stopping electrocutions, which is what the requirement is all about.

Extend the box

I don't like removing the box. It's delicate "dental" work and if you aren't experienced at it, you risk goring up the drywall, or worse, the old wires (and then you're really in trouble!) The original box was nailed at the joist before the drywall went up, and may be steel (and might even be grounded!) "After-drywall" retrofit boxes are plastic, hokey, weak, and clamp to the drywall... likely it'll flop around, or tear out of the wall when trying to pull a stubborn plug. No thanks. On the other hand, if you're a drywall god, then properly fit new-work boxes, but honestly I still prefer metal boxes.

So how do you make a box bigger? Here's an unrelated question. How do you attach surface conduit like Wiremold to an existing flush-mount box? With an extension adapter box that brings it out an inch or two and has side ports for the Wiremold. We only care about the first part. It's not the normal parts source, but it works.

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Put the GFCI protection elsewhere

GFCI, after all, is not a socket. It is a system of protection that can protect any part of a circuit, including many sockets. You only know it from the convenient GFCI + receptacle "combo" that you're used to seeing. It comes in other forms also, such as a separate "box" or a breaker.

This will protect all of the circuit that is downstream from the GFCI. However, this itself may be a problem. If other parts of the circuit have any defects -- such as crossed neutrals with other circuits, or a hard-wired device which in fact does have a ground fault -- the device will trip and refuse to reset. Then a time-consuming search for defects will be necessary.

At the circuit breaker

The breaker version replaces the circuit breaker on that circuit, with a combo unit that is both a circuit breaker and a GFCI. It provides GFCI protection for the entire circuit. This can be expensive or impossible, depending on the model of service panel (breaker box) your home has. For instance, GFCI breakers for Pushmatic are hard to get.

This requires opening up the breaker panel and replacing the breaker. This is short work for an electrician.

Somewhere along the cable

It is possible to fit a junction box just outside the breaker panel, run the circuit's cable to this junction box, and fit a GFCI device at that location - then run a short cable to the breaker panel so the GFCI can get supply. That allows you to use a GFCI module like a deadface (which you notice looks a lot like a GFCI+receptacle combo) -- or simply use the normal combo device (if Code allows; there are new rules about bathroom and kitchen receptacles not supplying sockets anywhere else.)

Since US circuits are generally wired as a chain, another option is to find a receptacle location upstream of the bathroom, and locate the GFCI device there, wiring it it protect the downstream parts of the circuit including the bathroom.

Labeling and Testing

If you GFCI protect another receptacle, you put a sticker on the receptacle that says GFCI Protected Outlet. Receptacles that are GFCI protected are allowed to be 3-prong even if they're not grounded.

If that receptacle does not have a genuine ground, also label the receptacle No Equipment Ground.

The stickers are what the electrical inspector is looking for. They are not special, you can print them on a printer.

How do you do a serious test of a socket that is GFCI protected? With an external tester. An external tester won't work on a socket with "no equipment ground" and that's not a defect, that's expected. Plug it into a three prong adapter (cheater) and run a long length of wire from the grounding tab on the adapter, to somewhere you can get a solid ground. E.G. the ground bonding wire exiting your service panel.

  • If the OP has grounded metal boxes and uses a box extender to install a GFCI receptacle, will the mounting tab on the receptacle ground the receptacle and allow the test button to function? Or should one put in a ground wire pigtail to the box? If no pigtail is used, should one sand off the paint under the tab to achieve electrical contact? – Jim Stewart Nov 13 '17 at 18:03
  • So if the receptacle is not grounded, then the test button on a GFCI receptacle will not work, right? The simplest auxiliary temporary ground that I can imagine for one person testing is to plug in a long enough extension cord into the GFCI receptacle to reach a ground and fit a short jumper with an alligator clip to attach to the ground. – Jim Stewart Nov 13 '17 at 18:33
  • @JimStewart two quesitons, first would the receptacle yoke would land hard enough on the extension box, probably if the paint's not in the way. Second is whether the extension box would have firm enough contact with the original box to shunt ground. Enough for a tester or GFCI tripper down the screw head and thread, probably. Enough for a bolted fault, depends on the hard contact area. – Harper Nov 13 '17 at 18:58
  • @JimStewart sorry I deleted and rewrote my earlier answer, it didn't show your reply. I agree without a ground (or some other third path) you cannot have a GFCI trip. The long extension cord is a great way. Better way than what I said, if you have a grounded recpetacle in the house. – Harper Nov 13 '17 at 19:00
  • You could use a water pipe or take it into the room with the electrical panel and clip it to the exterior of the panel. – Jim Stewart Nov 13 '17 at 19:55
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The first problem is common with older homes. I usually extract the old (likely metal) box surgically by cutting the mounting nails inside the box, and then I install a winged remodeler (old work) box, which is much larger.

You'd only use the grounding screw on your new outlet if 1) there's a grounding conductor in the cable, or 2) you need to ground to a metal box which itself is grounded. Neither apply to you. It is acceptable to install ungrounded GFCI outlets where no other option exists.

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You can install a GFCI receptacle without a ground, and it will protect you from a ground fault shock. I suppose that some types of GFCI receptacle might require a ground; verify that the particular one you have will work without a ground.

If you don't have enough room in the box to accommodate a GFCI receptacle that occupies a lot of volume, you could put in a deeper box which would fit in the same hole in the finish wall. This would require removal of the old box and this is higher in skill/tool level than just changing a receptacle. You may be able to get a GFCI receptacle which occupies less space, or you may be able to rearrange the wires in the box.

Is the wiring copper? If so, is it #14 or #12? How many wires are in these boxes?

Another approach would be to achieve ground fault protection by changing to a GFCI breaker in the panel. This would allow you to keep a standard receptacles in the wall boxes But this requires removing the "dead front" of your electrical panel to change a breaker. Depending on the age and design of your electrical panel there is some risk in doing this. Determine whether GFCI breakers are available for your panel and that there is space available for them in your panel, because in some panels the GFCI breakers take up more space than standard breakers.

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