Peter wrote:
House wiring is about 25 years old (built 1979). Aluminum wiring.

Residential home. I did check other outlets, lights, breakers etc. They all
seem to work. Voltages at the breaker panel measured about 130 volts to
a ground wire. (I did not test to neutral). Voltages at all receptacles is
in the range of 124.6 to 124 8.


So it was easy to narrow down to one circuit.
I pulled apart the switch boxes, and two fixtures, plus a ceiling box that was
originally used for a ceiling light, checking all connections.

There is power up to a receptacle
box..... and (after testing continuity at different boxes) I finally got to
the point where I could identify the first ceiling fixture junction box after
the receptacle. At this fixture junction I removed the fixture and pulled apart the hot
and neutral connections andcontinuity tested every wire using a DVM to find which
pair of wires went to the receptacle and which continued to other fixtures.

And then, I connected the two wires together at the fixture junction box (power
off)..... and disconnected them from the preceding receptacle.. No continuity in this
loop. I checked the hot (black) from receptacle to fixture and that had continuity. but
the neutral did not.

Also powered on the circuit and used a light probe to ground to check for voltage. There
was voltage
at the first fixture junction box and nothing at anything beyond that point..
which makes sense because I had disconnected everything else from
that fixture box.

A three prong electrical tester showed all receptacles to be wired correctly.

I was up in the attic looking for squirrels, there was no way they could have
gotten to the wiring.

That's why I'm confused because usually wires in the wall are usually solid,
except when conditions change for whatever reason, construction, damage
overheating, etc. But everything was normal...and suddenly it didn't work.

I don't have much more than the standard experience with switches, fixtures
and receptacle so feel a little over my head at this point.


OK, unless someone can come up with an explanation, it sounds like the neutral
parted. Weird.

As for replacement, if you can route through the attic, then it should be a
simple matter of using a wire fish to bring the cable up from the switch into
the attic and then stringing it across to the light. If it isn't accessible
through the attic, it gets nastier, since you're usually looking at cutting a
couple of access holes in order to do the fishing, and then patching the drywall
later. Not rocket science, but a hassle. As to hiring it out, personally
the only thing I'd hire out would be the drywall repair, but I'm a lousy
drywaller. YMMV.