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I was drilling a hole through a wall next to the floor in the corner to put Ethernet cable through.

All went fine, however, when I got to the other side there was a piece of copper wire on the drill bit. I pulled it (not hard) with pliers and extracted about 15 inches piece of wire (no isolation, no anything).

Lights didn’t go out, no sparks or anything.

What could this be? Some random piece of non-isolated wire not attached to anything?

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  • What is the diameter of this wire? – Jim Stewart Jan 27 at 14:03
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    Shoot us a pic, with a nickel nearby so we can get a sense of size. Also if your country has a nickel that's 3 inches across or something, let us know that too, – Harper Jan 27 at 16:47
  • Don’t have a pic :( ~15 inches long, 1-2mm wide. – psh Jan 27 at 20:09
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It sounds like you hit a ground wire, was it still attached at the other end? If it was my house I would make access to get inside the wall to see, or buy one of those bore cameras and look in the wall that way. Please l`et me know if it was attached though.

Santa

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    Felt like it wasn’t, I really didn’t pull hard and it just came out. All outlets and lights are working fine. – psh Jan 27 at 8:01
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    @psh of course it works fine. There are 100 ways to create an unsafe condition in which all the gadgets still work. Strictly speaking, things like grounds, GFCIs, circuit breakers, jacketed cable, fuses and all that are completely unnecessary and a house can work for years with none of them. But when it fails, it fails deadly. – Harper Jan 27 at 18:38
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First thing's first - you can't rule out that there may be live wires exposed inside the wall, so there is a potential hazard here. If you touch the live wire poking around in there, you could receive a shock, and that could injure or even kill you. It is also possible that the exposed wire could start a fire.

To be safe you'd want to turn off the breaker for the broken wire's circuit, but you don't know that it was power wiring, much less what circuit it's on. So the safest thing to do would be to turn off power to the whole house while investigating.

That's an awful lot of trouble for what may very well turn out to be nothing hazardous, but can you really take a chance with this kind of thing? I don't think so.

There are only a few likely possibilities for copper wire in your wall. It's either electrical power wiring or some low voltage wiring - phone, network, thermostat, doorbell, etc. Hopefully it turns out to be low voltage because the repair will likely be much easier.

The next step after turning off the main power just-in-case would be to look inside the wall and see if you can figure out exactly what happened and what you hit. At this point - with power off, no heat / air conditioning, no refrigerator, no lights, etc. - it may be best to just call in a pro for an emergency repair so that it's fixed quickly and safely. Keep in mind if you do find damage, you may wind up calling a pro to fix it anyway, so if you try to DIY this it may just be "prolonging the agony."

If you want to try to investigate, you may be able to see what happened with an inspection camera that goes into a bore hole. Of course you probably don't have one of these lying around the house. Even if you do, it can be hard to figure out what you're looking at in there, especially for an untrained eye.

You could open up a bigger hole to get a better look in there. You might want to cut out a hole and patch it up afterwards, or you could cut a hole for an old-work low voltage mounting ring - this way you can cover it with a blank cover plate once you see what's going on in there. If the hole you drilled is at receptacle level, you can match the height of the existing receptacles and this won't look out of place after the fact.

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  • I think shutting off the power would be over reacting. This would be an extreme inconvenience to the entire household. If this is a ground wire for a circuit or the major trunk ground wire, then it should be possible to determine this with an ohmmeter. Check for continuity between the neutral and the ground slots at a variety of receptacles. High resistance would indicate an open ground. Or use a plug in circuit tester. If there are circuits with hard wired lighting only, then some other tests would be needed. – Jim Stewart Jan 27 at 14:10
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    It's really a pain, but we already know it's not their lucky day, it's unlikely but still possible there's a serious hazard present - IMO you just bite the bullet and play it safe. – batsplatsterson Jan 27 at 14:36
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    @JimStewart I would say "having the rescuer also be shocked" would be an extreme inconvenience. Mortgages don't pay themselves. – Harper Jan 27 at 18:40
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    I would be more worried that it is the ground for the service panel. It could be old k&t that's not being used, killing all the power sounds overkill to me , but I would want a photo of the wire and would probably open the wall to know for sure. – Ed Beal Jan 27 at 19:27

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