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Was doing a reno on my bathroom and noticed there's an unterminated wire behind my wall, near the overhead vanity light fixture:

unterminated wire

I'm unable to trace it any further since it goes behind a stud, but there is enough slack for me to pull it down and test it with a multimeter.

If it's live, how do I safely handle it?

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To answer your question about handling the wire, I'd suggest you turn off power to the whole house, pull the wire to where you can work with it, spread the black/white/ground wires so they aren't touching, and strip a tiny bit of sheath off the black and white wires. Secure the wire so it's not likely to move around and inadvertently short out. Now you can turn the power back on and poke at it with your multimeter.

As far as handling it in the longer term, the following is based on the assumption that the wire is live, or can be switched live, so should be dealt with properly. If you do a bunch of exploration and convince yourself that it's always going to be dead, then ignore the following.

The textbook thing to do is follow it back to the source and nip it there. However, that might result in a lot of drywall repair.

Failing that, the best code compliant approach I can think of is to put an old work box in the next stud bay and pull the wire back and into it. Strip a bit off the wires and nut them individually. Apply a blank cover plate and you're good. (Turn off the breaker while cutting nearby and working with the wire.)

It does look like you could probably pull the errant wire into the existing junction box, which would be good, but you'd probably not get enough wire in (6") to be code compliant.

  • Thanks for the advice. I've managed to test it, and it is not live. – AgmLauncher Oct 30 '16 at 16:54
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    Make sure you switch on every electrical outlet and device (including lights) in your house before you conclude "it is not live". If somebody was dumb enough to leave an unterminated wire, in the wall, you don't know what else they were dumb enough to do or what the other end might be connected to! – alephzero Oct 30 '16 at 18:04
  • @alephzero it is not always dumb to leave a wire like that. Yes, it is better not to have dead wires in the walls, but sometimes it is not possible to remove them without a lot of extra work. I have a short section inside my bathroom wall because it was old, thick Romex in a hole barely large enough to pull it through and it was going around a corner. The only way I could have removed that section of wire was to remove a stud that had drywall attached on the other side. – user4302 Oct 30 '16 at 18:35
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    @Snowman when you do something like that tho you should leave it clearly labeled "Disconnected spare" or something like that, and the other end cut off short and labeled "do not connect" – Tyson Oct 30 '16 at 21:38
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    @AgmLauncher: A wire which you cannot fully trace all the way to the next juncture or its other end must be assumed to be "sometimes live", to be on the safe side, even if you can't imagine how it might become live. – einpoklum Oct 30 '16 at 23:33

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