Multiple outlets stopped working after wall-mounting TV

Question

I recently noticed that an outlet in the garage, a bathroom (GFCI), an outside outlet, and the irrigation system no longer work. I also recently upgraded the TV in the living room and installed a new wall mount for it (drilling four holes to do so). I do not notice any tripped circuit breakers. The bathroom GFCI outlet can't be reset (the button depresses, but then clicks back out, maybe because there's no current to it).

First, is it possible that installing the wall mount could've hit a cable that would power all of these different places?

How would I go about diagnosing this?

~~~~~~~ Update ~~~~~~

Going off of @jay613's advice of not over thinking things, and his suggested test, I did get current to the bathroom GFCI (which is further away from the panel than the spot I drilled holes for the mount). I didn't know how to safely test after that point with the meter though. Just guessing the path by things that weren't working after that point, the next outlet was an outside one.

After Unplugging a timer that was plugged into the outside outlet (not sure what it powers), I was able to reset the GFCI outlet in the bathroom, and the outlets in other parts of the house now work. I now believe that possibly the TV mount was coincidental timing, and either the outside outlet failed or the timer that was plugged into it failed (probably more likely)

Thank you very much for the help and insights. Very appreciated!

Answer 1

Here is how I would diagnose and handle this based on the information available here so far: ground fault interrupter interrupted and non resettable, breaker not broken, and all outlets that SHOULD be GFCI protected are dead.

The "don't overthink this" diagnostic is an actual ground fault, and a GFCI that trips faster than the breaker.

I would guess that the bathroom GFCI is being employed as a whole-house-where-required GFCI protecting the outdoor outlets, irrigation, and garage all fed by the load-side terminals from the bathroom. (Aside: This saved about $5 in construction costs. Woo hoo.) I would guess that one of my new lag bolts created a live to ground short in a cable running between any two of these devices, but NOT in the cable running from the panel to the bathroom. I would open the bathroom outlet and expect to find 120V on the supply side terminals, expect to see the load side terminals (the “don’t use these” ones) in use, and to find no voltage and a hot to ground short measured on those terminals.

If all that pans out, I wouldn’t do any more diagnostics, I’d take down the TV and rip open the wall.

And while repairing it, you now have the perfect opportunity to install a proper recessed outlet and other cabling behind the TV without brushing up your fishing skills. :)

EDIT: further suggestion. You might be able to reduce the amount of wall needing to be opened by removing one bolt at a time and trying to reset the GFCI. If you are lucky and that works you will know which bolt is at fault and only need to open a small patch of wall, that afterwards will be completely hidden by the TV bracket. Also, if it does work, turn off the breaker before proceeding further as you will have exposed live conductors while working in the area.

Answer 2

In wall electrical cables very often do transit from one wall stud cavity to another by passing through a hole bored through the stud. If you happened to drill a pilot hole for your lag bolts right into one of these cable pass through holes there are at least four possible things that could happen:

1. Nothing. The drill bit and bolt miss the electrical cable completely
2. Short. The drill cuts into the electrical cable in such way as to cause a hot to neutral short. This probably leads to a few sparks and the circuit breaker tripping in the panel.
3. Cut Hot. In this case the drill bit could have damaged the electrical cable to cut open the hot wire. Any downstream electrical outlets on this same circuit very well may end up being unpowered.
4. Cut Neutral. Similar to the Cut Hot case this can effect down stream devices/outlets on this circuit. This could lead to a very dangerous situation at down stream devices/outlets with an "open neutral" condition. This is particularly a problem if the circuit is a Multi Wire Branch circuit with both phases of the source power feed are fed down the same cable.

There are also other issues that could come up related to any GND circuit conductors may become shorted to either the hot or neutral wires. This can also be dangerous and would most likely to trip upstream GFCIs or GFCI breaker at the power distribution panel.

If you are not equipped to handle the problem isolation or have limited experience with this subject it may be advisable to bring in someone experienced in the field to help diagnose the problems. The potential dangerous situations with this are very real and should be addressed in a serious concern.