Need to hang mirror, AC detected from stud finder

Question

I'm a rookie with any sort of home renovation / improvement.

My wife asked me to try and mount a mirror, its heavy, about 40 pounds.

The mirror has two d-rings on the back and a big warning not to use wires for hanging. The recommendation is "L" hook for wood / struts , or anchors for plaster.

One of the d-rings would be exactly centered over a stud, which i figured is good, except that the AC detector happens to go crazy over this point. I scanned around this point, and about 4 inches above and below, the AC detector beeps / flashes loudly. A little further away the AC light turns on, but doesn't beep. A little more further away, there is no warning.

I figure there is a wire going through the stud? Maybe there is a chance I hit it?

I'm not sure how to get around this problem. I thought maybe move the d-rings up? They are about 12 inches from the top of the frame.

Will appreciate suggestions, thanks

Answer 1

If the mounting hardware would hit a cable, you need only move the mirror a few inches to avoid it.

Cut a small hole in the drywall / plaster and look in the wall. See where the cables go and hang the mirror in a way that doesn't hurt them. Cut the hole in a place that the mirror will cover, and you don't need to worry about doing a good repair job on it.

Answer 2

For USA jobs, the national electric code mandates a minimum of 1 1/4" from the edge of the wood to the cable (reference NEC Section 300-4).

In other words, if your screw mounts less than about an inch into the wood, and the wire was installed correctly, you're fine. I'd recommend using a bracket with a series of shorter screws rather than one big one. Chances are there already are drywall screws of about that length in the stud, and they're fine, so anything shorter than those is not going to hit anything.

Unfortunately it's hard to determine if you've nicked a cable. That's what AFCI circuit breakers are for, see elsewhere for details on that topic.