I'm quite an amateur when it comes to home improvement type stuff but I now have my first home and starting to do small work around the house. I kind of scared myself when I bought a drill and with the very first drill, I punctured a water pipe. Yeah, not exactly a good intro to home improvement.

Anyway, I'm planning on doing some more drilling and want to be safe. A water pipe is a PITA but at least the damage was minimal. I'm much more concerned about electrical wiring. I was going to buy one of those combined stud finders + live wire detectors but I don't need the stud finder part. I live in Indonesia where no one builds with wood frame + drywall construction. Everything here is concrete brick walls.

So, I saw these non-contact voltage detectors online and they look like they fit the bill but I wanted to check here first. Would that allow me to find live wiring through about 1" of plaster + concrete?

This was the exact product I was considering: http://www.amazon.com/Fluke-1AC-A1-II-VoltAlert-Non-Contact-Voltage/dp/B000EJ332O

3 Answers 3


Almost definitely no.

I'm not familiar with that exact model, but typically non-contact voltage detectors are designed to have to be within a few mm of the wire to work. They're called "non-contact", but that means no electrical contact (i.e. they don't have to touch the bare wire). You'll just about have to touch the tool to the insulation of a wire for them to work properly, so it's not likely you'll be detecting wiring within any type of wall with one of these tools.

The description from the Fluke website for the Fluke 1AC II A1 VoltAlertTM Electrical Tester, seems to agree.

The next generation VoltAlert™ AC non-contact voltage testers from Fluke are easy to use – just touch the tip to a terminal strip, outlet, or supply cord...

Notice that it says, "just touch the tip to...".

  • I use that exact model on a daily basis, and I doubt that it would sense wires at the depth/density you're describing. Jun 8, 2015 at 14:03
  • Ok, in that case I may go with a more expensive, yet dedicated tool such a amazon.com/Zircon-MultiScanner-i520-Center-Finding-Electrical/…. Do you think something like that would be sensitive to density of material? They say it will find wires up to 2" deep but it also seems designed to work with drywall whereas I'll be dealing with plaster & concrete.
    – T Nguyen
    Jun 8, 2015 at 15:33
  • Again, I don't have any experience with that specific device. My advice would be to purchase one from somewhere with a good return policy, and then test it out where you know there are wires in the wall. If the results are not consistent, I'd return it. Since there are no studs in a block wall, these devices aren't designed (or tested) to work on such a wall. So it's not clear if they'll work or not.
    – Tester101
    Jun 8, 2015 at 15:48
  • 1
    A device like this Wall Scanner from Bosch might work for you. It says it detects copper wiring up to 2" deep, but also says it detects nonferrous metals up to 3 1/8" deep. The sales video shows a guy using it on a block wall, so I'd guess they've tested it on one. Maybe this specific device isn't right for you, but searching "wall scanner" might turn up more relevant results for what you're looking for.
    – Tester101
    Jun 8, 2015 at 16:03

If you hook an inductor (coil) up to your voltmeter, set it on AC, and place it next to a hot AC wire, you will read a voltage. You've created a simple transformer circuit. However, the effect is extremely distance sensitive. While 12mm separation is OK for 120v AC, and a good coil, you'll pick up nothing at 50 mm unless you have a very good voltmeter.

  • 1
    This answer will only work for a circuit that is actively powering something. if the device is off and current is not flowing, no electromagnetic field will be generated for the inductor coil to pick up. This is the reason most non-contact safety indicators sold today are capacitive. Capacitive sensors detect circuit wiring whether it is being used or not. Do not rely on inductive sensors to determine if there is dangerous voltage on wires. Feb 4, 2017 at 9:26

I have a Bosch detector and it does detect live wires in the walls.

Have not had the chance to check on concrete - our buildings are better constructed with lots of insulation... But does seem to find them at about 1" away.

It also picks up metal, like nails and screws under the surface.

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