Discuss DIYer with wiring mystery (detailed post) in the DIY Electrical Advice area at ElectriciansForums.net

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labboypro

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Long week, lots of health-related issues have me a bit distracted, and this bathroom rework project has got me completely stumped. I'm an experienced DIYer, but am a DC and logic circuit person by training, and this AC stuff has thrown me off this time. I caught myself literally scratching my head, so decided I'd throw this out to other, more focused minds.

Here's a pic of the wall box--


And some description to muddy things up. From left to right...

First 14/2 is a mystery pair that head off to the kitchen. Unless these are connected, the kitchen light doesn't work (that switch is, thankfully, also in the kitchen).

Next over, the 14/3 is an even bigger mystery. It heads up to the ceiling where a 1970's fan/light/heat lamp box was located. The fan motor was dead when we got it. I think it is because there was a 16v 'bleed' into that circuit when the adjacent light circuit was on. With the dilapidated fan box removed, all of these wires buzz continuity between ceiling and wall box and there is NO voltage on them (which is where you might start scratching your head as well). However, there is a SEPARATE piece of 12/2 in the ceiling that comes from a mystery location. It is hot... ask me how I know, even though the breaker for the fan unit was off when I was removing it.

And then the 14/2 on the right is mysteriously operating a wall light over the vanity. Yes, black in/white out on the one piece of romex works the wall light. Still scratching? Well... the light in the old vent fan assembly used to come on with that same switch-- so, switch on, you get wall light and overhead light. I feel like there is a relationship to the mystery hot 12/2 I mentioned in previous paragraph.

The new fan assembly has only 2 circuits-- fan and light. The goal is to have switch 1 (far left) run the fan, and switch 2 (middle) run the overhead light in that assembly (and then switch 3 (on right) just lights the wall fixture over the vanity. Pretty simple from a plan perspective. There is zero attic level access. I do have a 11" x 11" hole in the ceiling where the new fan will go that has allowed me to at least study these wires a bit, but I cannot actually chase them.

Clearly color codes got thrown out the window by someone, and I suspect someone has "gamed" wiring runs (like the switch on the right I described above) to avoid having to pull new cable, which is simply prohibitive in this home because of the way it was built/reworked over the years. I don't believe there are any safety issues... just a mess to have to work on.

Thoughts? Suggestions? Blank stares?
 
TL;DR
Bathroom rework with mystery situation. Looking for some over-the-Internet expertise to get me going again. Post includes lots of details that may or may not muddy things up.
I like this. It’s funny.

when it comes to fault finding there is no difference in the thought process between ac and dc, so have a beer and go back to it with a fresh head the following day.

did this ever work? If so, then it’s just a case of knowing what goes where.

Are you sure everything on the ends of the cables are working ok, including the switches

do you have a tester (multimeter) that you can do some dead testing with?
 
I like this. It’s funny.

when it comes to fault finding there is no difference in the thought process between ac and dc, so have a beer and go back to it with a fresh head the following day.

did this ever work? If so, then it’s just a case of knowing what goes where.

Are you sure everything on the ends of the cables are working ok, including the switches

do you have a tester (multimeter) that you can do some dead testing with?

Thanks for the reply. I did two things... 1) slept on it (or, rather... lay awake all night pondering the problem), and 2) the next day, pulled apart the mystery kitchen light switch in the other room. Voila. It was being fed 2 different hot circuits. I removed one, and the pieces in the bathroom fell into place. I just buzzed all the wires one more time to make sure I knew what I was working with, and now I have a working fan assembly with separate light circuit (switches #1 and #2). The mystery 12/2 was literally just an extension off the round pan box for the vanity light, so I capped it off and tied it up out of the way of the vent assembly. The strange black/white thing on switch #1 appears to simply someone repurposing existing wiring at some point as I suggested in my OP. That piece of 14/2 goes straight to the vanity light, and represents "black/black" coming down from that box to switch the circuit. That vanity light gets its hot wire from another bathroom on the other side of the wall. So... all is now working as it should, it's safe, and I'm OK with a little color-incorrectness on the one circuit since I'm the only one around here who would ever be working on it in the future, unless I'm dead... and if I'm dead, well...

Anyway, thanks for the advice above. Beer and sleep were just what was needed.
 
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