I’ve found some doozys in the electrical work at this place. The ones I remember:
A sink light fixture with a built in plug on the side had hot (line) and ground wired together. Both hot and neutral (return) from the cable had lost about 3 cm each of insulation. The exposed conductor was all silvery (which made me really afraid it was aluminum).
The 30 ammp outlet for an air conditioner was connected to a 60 ammp breaker in the panel board. This was done by wiring both hot and neutral to the (double pole) breaker. Unsurprizingly the thing didn’t work when plugged in. I’m not going to use it anyway (it is decades old and has to be highly inefficient by now) so I disconnected that line from the breaker, removed both, and bought a space filler for the panel board. The outlet I also removed and replaced with a blank coverplate.
For a house this old, all of the original cables in the walls have grounds. None of them were connected. Instead, the installer wound the bare ground tightly around the outer insulation of the cable and left it there. To get my UPS to not complain about a site wiring fault (open ground), I had to systematically open 5 junction boxes in the basement (with the power off, ofc), remove the cables from the box, unwind the grounds, return the cables to the box, twist the grounds together, reconnect everything else, and close the box. In the process I dropped a ceramic light fixture twice (it shattered the second time) and could not get another one to fit back on.
This extends to the downright bizzare: in some rooms (kitchen for one) the grounded cable is run to the outlet box, the ground treated as above, and an ungrounded outlet installed. The refrigerator is using one of those “cheater plugs“. An outlet in a bedroom is similarly done, but if I connect the grounding wire from the cheater to the junction box, I have a legit path to ground (so claims my UPS). Odd.
This place has more “current taps” (wall hugging power strips) than I can imagine uses for. Mostly ungrounded, they were actually permanently installed (cover plate removed and unit screwed in place) except for the 2 on double gang boxes.
There is a shed out back (which is partially on someone else’s property) made from a “U haul” trailer off its axle(s) that has underground power run to it. As soon as I find out where that is coming from, I’m disconnecting it for good and getting rid of it.
There are mercury switches aplently, but none of them are the glowy type. I’m replacing them with above-spec switches that glow when off. The local “home improvement store” has Levitons, which cleverly glow different colors if they are single or double (“3 way”) throw: orange and white.
Not electrical in this sense, but there were 4 or 5 TV antennas strung in the bazement. I took them down and pulled the antenna wire out where I could.