80V in my A/C Outlet

[kresty]

Printer wouldn't work on an outlet we uncovered.  I figured the wires weren't connected or something, as we hadn't used the outlet in forever (decade?)

Eventually I decided to try to track it down and went downstairs to see where the wire came from the wall.  It kinda "looked" like it should've been connected to something, so that started seeming more curious.

Stuck the multimeter probes in the outlet.... 0V (well, close, it was doing the mV from life).  Oh, that's right, change it to A/C mode.... 80V

What!?!?!?! 80V How in the world does my 120V circuit land on 80V.  That's like nearly impossible.  About the only way that can happen is some resistance, which would be really scary as that basically means a fire waiting to happen.  

Plugged an incandescent light in to try to see if it glowed at all.  (Just to make sure).  Nope, and it dropped to 0V.  After a while we were back at 80V.  Then, suddenly, mysteriously, the light came on.  120V.  Ack!!!

Went down to the breaker box to figure out which circuit at least it might be on.  Tripped a bunch of likely ones (trying not to turn off the computer or washer) and eventually I flipped two and it went out!  Flipped them back on and it didn't come back on.  Either it was one of those two (yea), or it just happened to freak out right then.

Got a little bit of a red herring because this breaker was replaced to add a 240V circuit for the leaf, so I'd figured maybe I'd messed that up.  Took off the cover, but all wires were tight and read 120V.  (I checked ALL of them while I was at it).

Went back downstairs and traced the wire in the basement (fortunately we can see them all).  I'd been avoiding that somewhat because of my back, but Lara moved stuff.  Found it heading toward another outlet.  I went upstairs to see if I could figure out where it came in while Lara wiggled the wire. (It went into the back of an unfinished utility closet / beer brewing storage area so I thought I'd be able to see it).

Couldn't see it, but... the light blinked on & off with Lara's wiggles.  Clearly we'd found the problem.

Turns out that the outlet there (there was only one nearby, where the router's plugged in) didn't have the wire going to the next outlet connected properly.  It was screwed into a terminal on the outlet, but the screw had come loose or something.

Once we found it, it was an easy fix, but wow, it's kinda weird to imagine how we'd figured it out.  Really glad we can at least trace some of the wires in the basement.

[savagecreature]

I'm so glad it was so easily fixed. If I had been telling this story it would have ended with, "And we still can't figure out what's wrong with the damn thing!"

[kresty]

I'm so glad it was so easily fixed. If I had been telling this story it would have ended with, "And we still can't figure out what's wrong with the damn thing!"

It almost ended that way.  We thought it was just a disconnected dead old circuit and we kinda gave up on it for a couple weeks... but then we were doing stuff that would make it harder to fix later so decided to check.  Hence the voltmeter.

The 80V moved it from the "just forget about it and move on" bucket to the "gee, we'd better understand this" priority.