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Refinishing my basement. Been a 5+ year project, and I'm forgetting things. I have a white AC power wire in the ceiling, but I can't find where it goes or what powers it (it's not powered currently).

Is there a tool, similar to the kind you can use for Ethernet, Coax...etc, where I can clamp something onto it, and then use a gadget on various other wires to find out which is the wire in question?

Obviously I would just follow the physical wire if I could, but a good length of it goes under/behind drywall.

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If you happen to have a "toner/tracer" for one of those other wire types, and you are SURE the wire has no power applied (yes, you said that, but generically, one has to be careful when attaching things to power wires) you can simply try it. It may or may not work well enough to be of use.

You may be able to rent (purchase is unreasonable for someone not in the trade, IMHO) a more sensitive/powerful unit optimized for power cabling. Or you can purchase a more affordable but likely not all that capable unit which specifically claims to work on electrical power cables, but is likely otherwise similar to the network cable models.

Now, if you have a bare end (unpowered) and are trying to match other bare ends (unpowered) you can just use a multimeter - after verifying no voltage and no continuity between hot/neutral at each suspected cable, short one (hot to neutral) and look for continuity at the others, or attach a battery and look for the DC voltage at the others.

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  • I don't believe I have another bare end to check. Really not sure though. Do you think something like this will work? smile.amazon.com/Extech-TG20-Wire-Tracer-Generator/dp/…
    – Dave
    Oct 29, 2020 at 19:41
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    No idea on the specific unit. Generically, most low-cost ones have a hard time with finding wires in the walls that don't happen to be right up against the drywall. If you have exposed cables that you can touch the outside of they stand a much better chance. Start with asking any "techy" friends you may have if they have one.
    – Ecnerwal
    Oct 29, 2020 at 19:53
  • I don't have any techy friends that have one or know any particular ones that work. None of the ones online that I can find specify use for power wires - most mention ethernet or phone lines, but that's it. It doesn't say they CAN'T, but also doesn't seem to say that they CAN. Any thoughts on how I might search for one that would work with what I need?
    – Dave
    Oct 29, 2020 at 20:45
  • 240VAC tone/trace seemed to get plausible results.
    – Ecnerwal
    Oct 29, 2020 at 21:13
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Yes, you can search for "wire tracer" or "tone tracer" and you will find examples of tools that you can hook to one end of a wire and help you trace it through walls and ceilings to the other end of it.

In my experience these work pretty well as long as there is not a lot of electrical noise nearby. If so, you may need to shut off the power to that area of the home in order to get good readings.

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  • Probably a good idea anyway, so you don't get bit by the unexpected, such as a MWBC. Nobody ever died from turning off the main breaker. Oct 29, 2020 at 21:28
  • The ghost from the iron lung would like to have a word with you, Harper ;-)
    – Ecnerwal
    Oct 29, 2020 at 23:43

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