How to drill a hole near a wire in a wall?

Question

I am mounting a mirror in my hallway. I have plaster/lath walls and am planning on drilling a hole to insert a toggle bolt to hang the mirror on.

I marked the location and was ready to drill when I decided to use a non-contact voltage meter to see if any wires were in the area. It turns out there is wire going from a switch to an overhead light right though the area I'd like to drill my hole.

Obviously the first step is to flip the breaker, but I am not sure how I will know if I am damaging the wiring when I drill my hole. How do I drill the hole while knowing I'm maintaining the integrity of my electrical system?

Answer 1

Use the depth of the plaster/lath; say it's 5/8".

1. Put a piece of tape around the drill bit at 5/8" to ensure you don't drill deeper.
2. Drill the surface hole 5/8" deep.
3. Once the surface hole is made, you can turn on the electricity and insert a non-contact inductive wire sniffer (like this one from Fluke: https://www.amazon.com/Meterk-Non-Contact-12V-1000V-Flashlight-Multi-sensor/dp/B0711KGPYD).

Note this will only detect the "hot" line (not ground).