Is it possible to DIY my multimeter into a detector for active wires (charge flowing at that very moment) inside a wall?

I don't know, maybe something with a coil or metal plates?

The application would be localizing a wire in a wall so I know where not to drill into.

  • \$\begingroup\$ if it has an accurate current meter that can go down into the micro-amp range, you can use a current transformer to make a contactless current meter. Commercially these are available as 'clamp current meters' \$\endgroup\$
    – RJR
    Sep 15, 2020 at 14:08
  • \$\begingroup\$ I think my question was not properly explaining my use case. I'd like to detect a wire in a wall. Doesn't have to be super accurate. \$\endgroup\$
    – Raffael
    Sep 15, 2020 at 14:29
  • 1
    \$\begingroup\$ Okay, I didn't expect it to be that complicated. I thought that an active wire will just either induce a current or resistance in another wire hooked up with the multimeter by means of its magnetic field. And then I'd try to detect a maximum of the respective metric by hovering it over the wall. I just need to know whether the wire terminating at an outlet is coming from top/bottom/left/right. \$\endgroup\$
    – Raffael
    Sep 15, 2020 at 14:54
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    \$\begingroup\$ In the USA, I would shut off the power to the outlet, open it, and look in with a flashlight or pull the outlet out of the box. Is something like that not possible where you are? I don't think anything really simple will give you a signal that is sufficient to detect with a multimeter. \$\endgroup\$
    – user80875
    Sep 15, 2020 at 15:12
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    \$\begingroup\$ The short answer is no a multimeter cannot detect a cable inside a wall. Some "stud detectors" will detect a cable inside a wall (some don't).. A tool called a cable tracer will definitely detect a cable in a wall (or buried up to 300mm in the ground), however you need to plug in a transmitter to a power point first. \$\endgroup\$
    – BobT
    Sep 16, 2020 at 10:07

1 Answer 1


You won't be able to reliably detect any current flow through the drywall/sheeting on your wall without using some active components. One of the comments suggested a metal detector which is basically what you're creating with some wire loops, a transistor and a power supply. Check out this $10 diy metal detector kit to get the basic idea: Elenco Soldering Metal Detector Kit

There are cheap passive non-contact detectors that'll work if you hold them up right in front of an active power outlet but that wouldn't work through a wall.


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