I have a hard wired security system. I just finished hanging drywall. During the process, I apparently damaged a wire to either one of 4 windows or the door because I am getting a fault in the basement zone. I have used a magnet to test the sensors and they seem to be OK. Therefore, I believe I damaged one of the wires. I have not taped or mudded the drywall yet, so I can easily get back into the ceiling or wall to repair it, but I need to know which wire to repair in order to avoid removing a lot of drywall unnecessarily. The wires in the box are not labeled. Is there a way to identify which wire goes to which window?

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  • Are all the sensors in your basement on one wire? Jan 3, 2017 at 15:31

1 Answer 1


First, cut power to the alarm system.

Get your hands on a multimeter with a resistance setting. Run a long extension cord (unplugged) from the broken sensor to the panel. Put a probe on each end of the cord (ground pin is easy to remember; it only matters that you're both on the same conductor).

If you're lucky, you and an assistant will probe wires until you get a no-resistance reading. That's the intact wire of the pair. The rest writes itself.

If you're not lucky, you'll have cut both conductors and will have to run around identifying all your wires, in order to find the severed one by elimination.

Or, for around 40-80 dollars, you can get a tone generator and find your break in 5 minutes. The upside to this plan is that you won't have to run new wire -- you'll just locate and fix the existing. I own this one, though there are more/less expensive options: Fluke toner

  • Just looked on Amazon... Tone generator with probe can be had for $22 and it's definitely the route to take here.
    – Tyson
    Jan 3, 2017 at 18:13

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