SUMMARY: Electrical repair
I went outside to plug in my one string of Christmas lights for my garage this year (out of the hundred or so strings that I own), and the plug on the right outside garage wall didn't work. (I tested the lights elsewhere, so I knew they were OK.)
See, when I bought the house, I had an electrician add a dedicated circuit with outlets in handy places specifically to make it easy to display Christmas lights to my heart's deepest desire. And now it wasn't working. I knew that the first outlet before the circuit breaker panel is a GFCI* and that, sometimes, like if there's too much moisture or some other insult to its integrity, it'll switch itself off.
So I pushed its little Reset button, then its little Test button, then Reset again, and nothing happened. That could mean that the GFCI is broken, or it's possible that that could mean that the circuit breaker itself had flipped itself off (or was defective) so the GFCI had no power with which to reset itself. So I went to the circuit breaker panel, where I cleverly, years ago, clearly labeled which breaker belonged to the Christmas circuit. It didn't look tripped (lower right ones in the panel), but I flipped it off and on anyway. Made no difference.
I know how to replace a GFCI outlet, but don't know how to test whether the circuit breaker is bad. I could've just bought a replacement outlet and tried replacing it, but hip and knees hurt too much, so I appealed to Nextdoor for anyone who might be able to help with this, at the going rate. A very nice neighbor came by with his gear, and he went through the same steps, but also pulled the cover off the GFCI and tested the wires in the wall, and sure enough, no power coming from the circuit breaker.
He asked whether there were other outlets on the circuit, and I said yes, and they don't work (because if there's no power to the first outlet...) and don't have GFCI outlets themselves, but we went around to the front of the house and tracked the conduit for the wire under the porch roof and he double-checked those outlets himself, and noted where the conduit headed into the wall on the left side of the garage.
And he said, so, can we see where that comes through inside the garage? So, we went into the garage, and traced where the shiny unpainted conduit came through the wall, led across the ceiling, turned and headed towards the back wall where the circuit panel is located (bottom center left below the paper bags on the shelf). At this point, we've been at it for probably 20 minutes, after my initial 10-15 on my own. And it's starting to rain.
So we walk back to examine where the conduit comes out from behind the shelf, and interestingly, it branches--one branch goes into the wall and down behind the circuit breaker panel to connect to the circuit breaker, as expected. But the other branch descends outside the wall.
"Huh," he says, looking at the other descending branch, "What does THIS do?"
(Now, refer back to the 2nd photo in this post.)
So, anyway, now my Christmas light outlets work.
* Ground fault circuit interrupter--means if it gets wet, the switch on the outlet pops off so nobody gets shocked and nothing burns down.