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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.

Neil Steiner
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    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. https://www.youtube.com/watch?v=pwziu8RGF4A – NoSparksPlease Sep 19 '21 at 05:16
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    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](https://www.today.com/home/newer-homes-furniture-burn-faster-giving-you-less-time-escape-t65826), house fires. – Harper - Reinstate Monica Sep 19 '21 at 06:22
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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.) – Aloysius Defenestrate Sep 19 '21 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 '21 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 '21 at 19:21
  • @bsautner Replacing the GFCI outlet with a GFCI breaker would of course work, but at this point with a whole bunch of other outlets already changed, my preference would be to stick to the current approach. – Neil Steiner Sep 20 '21 at 02:03
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    @J... I measure the inside of the box as 3 5/8", considerably narrower than the 4" I would have at 2" per gang. Your suggestion to replace the box is a good one, but in this case I am trying to avoid rework in that particular part of the house. DrSparks' answer and a related comment seem to indicate that wrapping receptacles with electrical tap is acceptable, so I will probably take that approach. – Neil Steiner Sep 20 '21 at 02:08
  • When asserting that something is a code violation, it helps to add to your credibility to cite the code that is being violated. – DrSparks Sep 21 '21 at 02:18
  • @DrSparks Table 314.16(A) - there are no listed device boxes narrower than 2"/gang. – J... Sep 21 '21 at 02:32
  • @J... -- as long as the box is volume marked, it's still legal for use. HOWEVER, if it *wasn't* volume marked, it wouldn't be legal for use as a switch box either given that it's not one of the Table 314.16(A) sizes -- see the text for 314.16(A), especially 314.16(A)(2) – ThreePhaseEel Sep 21 '21 at 23:34
  • @ThreePhaseEel Fair. I could see an inspector going both ways, to be honest. Ultimately the installation has to be sensible, and if there's not more than a whisker between the hot screw and the box I could see it being flagged. An old 1960s skinny switch would be fine in that box, for example, but even if it was volume marked and the fill was OK the tight clearance is cause for concern on its own - it's barely suitable for purpose with a GFCI in there. – J... Sep 21 '21 at 23:43
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    The OP mentioned that he's upgrading outlets __in his kitchen__ which would necessarily require GFCI. To @DrSparks 's correct observation, I would add that I believe all circuits should be AFCI protected now as well. So why not use a AFCI/GFCI dual function breaker and be done with it? – GlennML Sep 21 '21 at 16:32
  • A dual function breaker would make the most sense in this situation, but there is no code violation here that makes this compulsory. The problem with NEC 314.16 is that is just calls a device a device, and has a one-size-fits-all approach to calculating box fill. It doesn't take into account some of these (probably unnecessarily) large profile devices, which are probably due to a lack of engineering effort or use of of cheap components. – DrSparks Sep 25 '21 at 20:28
  • @DrSparks There are provisions in 316.14 for large devices like GFCIs that extend significantly into the box and how to count them for box fill, but all of those rules are based on standard trade size boxes that are 3"x2" and vary only in depth. I haven't gone as far as the UL listing, but likely there there's something basing the approval on being installed in a standard 2" wide device box. Either way, an inspector always has some latitude to make a judgement call in edge cases like this and a tight fit, nonstandard box is reasonable cause for them to call to have the box replaced. – J... Sep 25 '21 at 21:22
  • I would say if you had to beat the wires back with the handle of your screwdriver and bash the device in with the palm of your hand, you may be in violation. – DrSparks Sep 25 '21 at 21:44
  • @GlenML Thank you for the comment about GFCI requirements in kitchens. I was going to point out that this location is 10’ or more from the nearest plumbing, but then realized that code seems to require GFCI on all counter surfaces, so it does apply my situation. – Neil Steiner Sep 26 '21 at 23:52

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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.

DrSparks
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  • I have seen a lot receptacles wrapped with electrical tape. But my opinion it is not esential. Electrical boxes are not designed for that. Properly stripped wires will not cause any problem. May be OP has some damaged insulation, it is more common. – user263983 Sep 19 '21 at 15:23
  • doesn't the "electrical tape" (at least the sort you buy casually; don't know if electrical supply stores sell different stuff) tend to get un-sticky and fall off over time? – user253751 Sep 19 '21 at 20:30
  • Nah. If you get the crappy PVC kind. Get some good 3M vinyl tape. And it's not essential, no, but it's a good idea when you have modern devices, which are quite wide, crammed in an old style metal switch box that hasn't changed since the turn of the century except for the 10-32 ground tap. – DrSparks Sep 19 '21 at 20:45
  • @user263983 In this case the short wasn't between any of my wiring and the box, but between a properly tightened receptacle screw and a somewhat loose metal flange on the inside of the steel box. But could you clarify what you meant by "electrical boxes are not designed for that"? – Neil Steiner Sep 20 '21 at 02:13
  • @DrSparks I'm surprised to hear that wrapping the receptacle with electrical tap is acceptable, but that provides a really simple solution for my current problem. Many thanks for the information. – Neil Steiner Sep 20 '21 at 02:16
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    @NeilSteiner Wrapping in tape is [not forbidden](https://diy.stackexchange.com/q/219053/41369), 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 '21 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 '21 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 '21 at 15:50
  • Electrician wrap the electrical tape around receptacle for case, when receptacle taking out without power off. But it is a bad practice. – user263983 Sep 20 '21 at 18:39
  • Some people here seem to have some strong feelings about electrical tape. Very strange. I've been an electrician for 20 years and it's something that has been standard practice in my trade. As for burning, I don't know what you're talking about. It's made of the same materials as the wire insulation and Romex jacket. It's designed to not burn... It's electrical tape... The bottom line is the box is too small for the devices installed. As I said before those are switch boxes. So the easy fix is to tape the sides of the devices. It's not a hack. It's trade practice. – DrSparks Sep 20 '21 at 23:21
  • @DrSparks [Super33 tape](https://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu9n_zu8l00x482Bmx_Znv70k17zHvu9lxtD7xtBevSSSSSS-) (the king of vinyl electrical tapes) falls under [NFPA flammability](https://en.wikipedia.org/wiki/NFPA_704) category (1) - flash point above 93C, but very much still flammable. It shares this category with materials like mineral oil and ammonia. Tape is heat resistant to a point, and fire resistant to a point, but an arc flash is very hot and can readily ignite PVC, which will certainly burn and produce quite noxious byproducts as a result. – J... Sep 21 '21 at 00:29
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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 '21 at 00:39
  • @DrSparks No difference. Vinyl is the common name for polyvinylchloride, or PVC. Same thing. – J... Sep 21 '21 at 03:24
  • No it's not. There's a difference. – DrSparks Sep 21 '21 at 03:52
  • @DrSparks Nope - same vinyl as vinyl records (PVC), vinyl conduit (PVC), vinyl pants (PVC), vinyl shower curtains (PVC), etc. Obviously vinyl comes in an array of formulations and there are *dozens* of different types and grades of vinyl/PVC tape, all with different specifications intended for as many different applications. Maybe you're only familiar with two of those flavours of tape and have adopted a simplified shorthand where "PVC" means one of those and "vinyl" means another, but that's all it is - an oversimplification, and a misleading one at that. – J... Sep 21 '21 at 12:04
  • Say whatever you want, there's a difference composition to the cold weather stuff and the cheap crap. call it whatever you want. – DrSparks Sep 21 '21 at 16:15
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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 '21 at 16:35
  • Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/129987/discussion-on-answer-by-drsparks-how-do-i-keep-a-gfci-outlet-with-tight-clearanc). – BMitch Sep 25 '21 at 20:32
  • If a box is so small it's already shorting your terminals, wrapping with tape will make it even worse. The box will begin to erode the tape immediately. The tape may not even last through the installation process. Bad idea. – jay613 May 15 '22 at 12:11
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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.

J...
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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 '21 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 '21 at 00:45
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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 '21 at 00:52
  • @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. – Neil Steiner Sep 21 '21 at 01:16
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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 '21 at 01:22
  • @J... I think you and DrSparks have convinced me that I'm violating code if I try to put everything back together in this same box. I will either try to replace the box, or I will use regular outlets that require much less clearance, since this is not located where a GFCI outlet would be required. – Neil Steiner Sep 21 '21 at 01:40
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Why bother using boxes at all? Reasons. When you get down to the reasons we use junction boxes, metal is better at every single one of them. All that to say, don't let this deter you or make you think metal is worse somehow. It's better - a lot better.

There is nothing wrong with an outer wrap of tape around the sides of a socket. Note that good tape is somewhat stretchy, and go ahead and wrap it with some tension so it'll conform. Finish in a straightaway so it'll stay down flat.

  • It's not going to drill through the tape and short anyway, because there isn't dynamic pressure there.

  • If the adhesive dries up and falls off (not something I'd expect from 3M Super 33), it will stay put if the clearance is close. If not, it's not needed.

  • If it was a bad idea, UL would not have listed "broccoli wrapper" rubber-band products such as Ideal Armourband, listed for this exact purpose.

I do it whenever it's useful, and I'm not going to stop anytime soon.

That said: GFCIs and other "fat" outlets are a murderously tight fit inside standard steel boxes, particularly 4x4 metal boxes and their derivatives (yours is not a 4x4). When able (either surface-mount or drywall-off new work), I recommend using a 4-11/16" square box and appropriate mud ring or domed cover. That will provide ample "elbow room" to avoid this problem.

Grounds in metal boxes. Remember that in metal boxes, you MUST run all the incoming ground wires to the metal box FIRST. At that point you can simply mash all the ground wires into the back of the box and forget all about them, if any of these things are true:

  • the device is a switch
  • the device is marked "Self-Grounding" (all GFCIs and some USBs are).
  • the device's yoke has hard-flush metal-on-metal contact with the metal box's frame, domed cover* or mud ring... with the screws run down all the way.

Only if none of those are true do you need a ground wire (el cheapo outlet floating on drywall ears).

* Domed cover must have crushed corners so it has hard flush metal-metal contact with box frame.

Harper - Reinstate Monica
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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

BillsJar
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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 '21 at 01:51
  • Yes, a 4-11/16" steel box with a mud ring would be ideal, but *damn, that's a lot of work*... – Harper - Reinstate Monica May 15 '22 at 06:01
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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.

user141814
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    What is a "battleship" in this context? – Machavity Sep 21 '21 at 14:13
  • Point well taken, @Machavity, I only knew because of [this comment](https://diy.stackexchange.com/questions/235001/how-do-i-keep-a-gfci-outlet-with-tight-clearance-from-shorting-inside-a-steel-el#comment450711_235001) – FreeMan Sep 21 '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 '21 at 01:48