Having trouble with the back wire on GFCI's popping free. 20amp, 12 gauge wire. When I fold the wires into the box, they like to come free of the back wire hole. I suspect this is due to the difficulty bending the 20 gauge wire to fit into the box.

I've read this which suggests I should be using the back wire on the GFCI. A few other web sources say the same thing.

Earlier, I had a problem with just being at the conductor fill limit of what could fit inside the outlet box because I was using two GFCI outlets. I was unhappy with this and am rewiring so each box has one GFI and one normal 20amp outlet downstream. The GFCI is pigtailed. The regular outlet is side wired to the GFCI outlet so it protects the standard outlet.

I feel like I should side wire the GFI outlets because they keep popping out from the back wire, BUT numerous sources say that GFCIs should use the back wire. This is a proper back wire that gets screwed down, not the "Quick Wire" push in wiring. I'm hand tightening as much as I'm able.

I suspect it's the process of folding the wires into the box, with the 12 gauge being so stiff, that causes the wires to come loose. However, on the outlets I've done so far, I was able to eventually make it work. But in one case, I was getting an error with the GFCI tester, and it was because the neutral wire had popped out. I fixed it, but concerned over the long term if they might work their way out.

3 Answers 3


I'd have to suspect that you are perhaps not always getting the part where the wire actually ends up between the plates right - to Quote @shirlocks answer "Just be sure to tip the device so the grab plates open before inserting the wires." If the wires are in the right place and the screws are tight THIS flavor of back wiring is VERY secure (as distinct from the push in springloaded that I will never use.)

It is generally advantageous to prebend the wires a bit before stuffing into the box, but there's no way the wires should come out if they are clamped correctly.

If the wire is not between the plates (so it's sitting outside them) it's not going to be clamped very well at all. Grab one, (out of the circuit) and look at it carefully under good light with the screws open as you move it around, and you should be able to see what's going on there, and have a better idea of what to look for when putting the wires in.


Unless the specific device requires it, there's no requirement to use the back wire terminals. It's simply a personal preference to do it that way.

If you're having trouble using the back wire terminals, it's probably safer for you to not use them (unless of course the device requires it).

You'll also want to check the markings on the device, and read the documentation, to make sure the back wire terminals are rated to accept 12 AWG conductors. If they're not, you shouldn't be using them with 12 gauge conductors anyway.


You could rewire it with stranded wire pigtails, this would add flexibility and relieve stress.

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