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I was replacing outlets and faceplates in my kitchen, finding mostly original electrical boxes or blue old-work boxes, and everything was going fine until I tested a double-gang GFCI outlet and outlet + USB box and saw a lovely purple flash before the breaker tripped.

That's when I realized that this box is actually steel and not gray plastic, and because of the very little clearance, along with a guilty little metal flange, the hot terminal shorted to the grounded box when I tried to reset (turn on) the GFCI outlet.

enter image description here

As you can see from the pictures, there is very little clearance here, but I thought these dual-gang boxes and these GFCI and USB outlets were standard sizes. It occurred to me that perhaps there are plastic inserts available for these steel boxes, but I can't seem to find anything like that. I did find some "low voltage" separators for plastic boxes at the store, but they're too thick. I could easily put some thinner sheet of plastic along the inside edge, but that probably wouldn't be up to code. Nor, I suppose, would be placing electrical tape over the flange and over the outlet side terminals.

This is the flange where a little bit of it or the GFCI side terminal or both vaporized:

enter image description here

And this is the GFCI side terminal, showing some discoloration on the lower terminal:

enter image description here

This is beside the point, but I connected the USB outlet as a load of the GFCI outlet, and to the best of my knowledge I wired everything properly. Amusingly, the GFCI and the USB outlet are likely still fully functional, but thank God for circuit breakers.

I doubt that I'm the first person who has run into this situation. Was there some way I could have avoided the short without prior experience? (And what is that little flange anyway? There are two on each side of the box, but the other three are flush against the side.) But most importantly, what is the correct way to resolve this without replacing the steel box with a plastic one? These specific outlets are the ones that I wanted to use, but if I am forced to use smaller things that cannot short out, I will have to go that route.

EDIT:

As requested by @J... I am including pictures of the receptacles from the back. The lighting isn't the best, but if you zoom in on the GCFI outlet on the left, you can see the LINE/LIGNE lettering on the top and the LOAD/CHARGE lettering under the sticker residue on the bottom, so I am quite confident that I wired this correctly. The LOAD from the GFCI outlet is wired to the USB outlet. I of course had to disconnect the LINE/LIGNE wires when I removed the receptacles from the box.

enter image description here

And from the sides:

enter image description here enter image description here

Because the metal flange was touching the LOAD terminal, it makes sense that this only shorted when I tried to reset the GFCI outlet, and apparently the circuit breaker trips faster than the GFCI outlet can react.

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  • 1
    The flanges are what's holding the box to the drywall, commonly called battleships, because when some are turned on side the look like ships. youtube.com/watch?v=pwziu8RGF4A Sep 19 at 5:16
  • 2
    Putting electrical tape around the outlet side terminals is fine. Steel boxes are superior for every single purpose junction boxes have, and they take care of grounding switches and many receptacles for you, so one less wire to have to cram. They also resist, not accelerate, house fires. Sep 19 at 6:22
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    Just FYI, junction boxes are not standard sized — older ones can be extremely small — and fitting gfci receptacles etc can be rough. Removing and replacing old boxes isn’t as hard as it might seem. (Especially if you have an oscillating tool to cut drywall and nails.) Sep 19 at 14:24
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    can you use a normal low profile outlet (non-GFCI) and replace the breaker with a GFIC breaker?
    – bsautner
    Sep 19 at 19:07
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    Leviton GFCIs are all 1.69" wide and the box should be 2" wide per gang, which means you should have 4mm or 5/32" of clear space on either side which is plenty to keep it well clear of shorting to the walls. That 2-gang box looks unusually narrow. What is the width of the box? Looks like maybe 1-7/8" each? With a modern, code compliant 2" gang box you should have no trouble installing without needing tape or any other hacks. I'd consider replacing that box if it's an ancient and odd (narrow) size.
    – J...
    Sep 19 at 19:21
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So those metal cut-in boxes are really designed to be gangable switch boxes, but there's nothing wrong with using them as long as you don't violate wire fill allowances. They are a design from an older time when electrical devices were much smaller. They are not up to standard sizes of today and are inadequate for modern devices containing electronics.

As for protection from ground faults, we as electricians wrap receptacles and switches with black tape all the time in metal boxes. Nothing in the Code prohibiting it and is a good idea to do.

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    @NeilSteiner Wrapping in tape is not forbidden, but it is a hack and it's unnecessary. In your case, the screws will eventually wear through the tape and it will arc again, this time possibly starting a fire since there's tape there that can now burn. Your boxes are below the minimum width to meet code, so they would be fine grandfathered (ie: left alone with their original devices) but once you open it up and make changes (as you have) then code requires that you change the box also. That's really what you should do.
    – J...
    Sep 20 at 12:23
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    What is the difference between "PVC" (polyvinyl chloride) tape and "vinyl" tape? I understand there's a difference between the "good stuff" (at a buck or more per roll) and the "cheap stuff" (5 rolls for a dollar), but isn't PVC made out of vinyl?
    – FreeMan
    Sep 20 at 15:43
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    @FreeMan Yes, even 3M Super 33 is PVC. The difference between the cheap brands is the vinyl formulation and the adhesive quality.
    – J...
    Sep 20 at 15:50
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    Well that's just false. Also are you talking about PVC or vinyl tape? There's a difference. And anyway, it's specifically designed not to catch fire. It just melts and by that time the insulation is melting off the wires too and it's time to call the fire department.
    – DrSparks
    Sep 21 at 0:39
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    Nobody is disagreeing that there's a difference in quality, it's that both the "good stuff" and the "cheap crap" are made of vinyl of some sort or other, and that "vinyl" and "PVC" refer to the same class of material. PVC can be made to a high quality with a high quality adhesive and last years, while it can also be made to a lower quality and/or have a low quality adhesive that might last months.
    – FreeMan
    Sep 21 at 16:35
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From the added information in the comments, this 2-gang box is only 3-5/8" wide which is insufficient for the two modern outlets which are installed in the photo. Standard device boxes are 2" wide and this leaves plenty of room for a clean installation without resorting to hacks like tape.

This old device box would be grandfathered and code compliant only as long as it contained its original devices. Once you open up the device box and make modifications it must be compliant to modern code standards when you are done. The best option here is to replace the device box with a larger, standard sized box. In your case it should be pretty easy - those four metal tabs just fold out and the box should slide out. You may need to open the hole a bit wider to fit a new old-work box, but ideally you probably shouldn't need to even patch or paint.

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  • Read my above comment about electrical tape. Also, are you a licensed electrician? Please explain how a short circuit would trip a GFCI breaker when GFCI breakers do not offer short circuit protection. They offer ground fault protection are a preset threshold. What the OP experienced was a short circuit. Technically it was a ground fault, but it was a bolted fault, which means we're now relaying on the panel circuit breakers instantaneous trip mechanism to interrupt the fault current, not the GFCI.
    – DrSparks
    Sep 20 at 23:26
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    GFCIs do not and are not designed to interrupt bolted fault current. The speed at which fault current rises if you were to graph it is way faster than the trip mechanism in a GFCI can react. The circuit breaker will always open first. It's likely the GFCI breaker wouldn't even trip.
    – DrSparks
    Sep 21 at 0:45
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    @DrSparks Ah, fair point. I've deleted that section of the answer. The outlet still looks to be miswired in the photo.
    – J...
    Sep 21 at 0:52
  • @J... As often happens, I regret that I'm not allowed to accept more than one answer, but I did upvote yours, and I do appreciate the many comments. Sep 21 at 1:16
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    @NeilSteiner Of course. If you do tape it, also make sure that the device screws hold securely and space it as well as you can just the same. You can use thin stock as a shim to make sure the outlet is at least some distance from the wall of the box before you tighten it down. If the outlet ever starts to come loose and wiggle it can still wear its way through a few layers of tape over time, so keep an eye on it from time to time. The broccoli band in the linked 'hacks' question almost seems a better idea if you're set that way.
    – J...
    Sep 21 at 1:22
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Replace the box with a newer box that has a little more clearance. You might need to shave away some drywall but who cares that's easy enough. Electrical tape is for hacks and adding an insulator on the side isn't ideal, you don't want anything in there extra that you don't have to

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  • Electric tape has been used by probably millions of electricians since the dawn of electricity. You're calling a lot of well qualified electricians hacks my friend. Also, how do you know it's drywall? Could be wood lath and plaster. Whole different ball game.
    – DrSparks
    Sep 22 at 1:51
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Take some long- nose pliers and clinch the battleships where they go around the front edge of the box. This will keep the battleship from wandering into the center of the box.

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    What is a "battleship" in this context?
    – Machavity
    Sep 21 at 14:13
  • Point well taken, @Machavity, I only knew because of this comment
    – FreeMan
    Sep 21 at 15:20
  • The F clips. They hold the box tight against the wallboard. I use a pair of dikes. Makes a really nice crease.
    – DrSparks
    Sep 22 at 1:48

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