Trying to replace an old outlet wired 12 gauge. I have encountered problems keeping the wire on the Leviton screws particularly when putting new outlet in the box. I read one posting suggesting a larger box may be needed, is this the only option? The house was built just prior to 1980--not sure if that is relevant.

C Scott (DIY newbie)

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    If the wires are coming off the screws merely from stuffing it back into the box, something is seriously wrong. – Harper - Reinstate Monica May 19 '16 at 21:44
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    Did you tighten the screws? Are you wrapping the wire in a clockwise direction around the screw? – Tester101 May 19 '16 at 21:54
  • Code also requires the screws to be more than 2/3 around the screw but not over lapped. this is explained in NEC exhibit 110.3 & 110.4 (nec hand book photos of right and wrong ways to terminate a solid wire). stranded wire requires a crimp fork or ring fitting in Oregon will look to see if NEC – Ed Beal May 19 '16 at 22:02
  • Just realized the Clamp was a form of compression so it is legal for the back and side or the 20A back clamp. – Ed Beal May 19 '16 at 22:10
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    Can you post photos? – ThreePhaseEel May 19 '16 at 22:56

You are generally not allowed to use backstabs with 12 gauge wire. If solid wire is falling off the screw terminals, tighten the screw a lot harder.

If stranded wire is falling off the screw terminals, a lot of people have trouble with that. There are techniques which help, like twisting the strands as you shape them, and making sure you are hooking in the clockwise direction. But here's another option.

This link here mostly compares screw terminals to backstabs. However, it mentions a third type, which they call "screw and clamp", and UL calls a "screw actuated clamp". That's the one.

Instead of a backstab, it provides a hole (often, 2 holes) almost immediately behind the screw. You loosen the screw, stick the wire in the hole and turn down the screw tight. The screw is threaded into a clamling plate, which squeezes down on the wire, clamping it firmly. Check the listing on each outlet but generally they are OK for stranded wire.

Last time I priced these outlets, they were in the $4 range rather than the 75 cent cheapies you can also get. Of course they are a much higher quality outlet throughout.

  • The ones you describe are usually called "back & side" from many vendors. I use these almost 100%. I wish they would outlaw "stabs" – Ed Beal May 19 '16 at 22:05

Odds are you are doing it wrong, (not surprising if you haven't done some before) but details become speculation with the lack of any pictures or detailed description of the problem.

Many modern outlets have clamps that are easier to use than going right to the screws - this is NOT the (detestable, and usually not 12Ga anyway) "back-wire stab" spring-loaded connections which I will never use, since they always seem to cause problems some years later, or occasionally sooner - these are slots that have plates that capture the wire when the screws are tightened, and are easier than the side-wire screw connections.

For a screw connection, you should form the wire so that it is "hooked" clockwise (the direction the screw tightens) and just large enough to fit around the shaft of the screw - and then you should tighten it fairly tight - there are probably actual torque specifications if you look up the outlet model - in any case, if the wires are coming off the screws, they are not on there right & tight to begin with. 12Ga wire does increase required box size for "box fill" - but that should have been done at the time of install, and wires popping off is not directly related to box fill, so much as stiff wires and less than good connections to the outlet.

One random Leviton outlet instruction does mention 14-16 inch pounds as a suitable torque value for both back wire and side-wire connections. If you don't have a "feel" for it, you may want to actually measure a few until you do get a feel for it. It's on the web in an annoying form where I can download it but not make a link to it - go looking if there is not a paper version included with your outlet, and find one for your specific model of outlet; pay attention to the "back wire instructions" if they apply to your outlet model.

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