Wiring problem

[Native_NM]

Mom called and said the hall light switch quit working.  She is 80+ and lives alone.  As a good son, I rush to the rescue.  House is 50+ years old.  Wiring is the old two-wire shielded, with no ground wire.  Some of the boxes are metal, some are plastic.  Fixture is a hall light, two switches.  As far as I know, it is the only light on the two switches.

I decided to replace both switches, because when I pulled the first one, it appeared to be original. or at least very old.  I picked up new, standard 3-way switches.  I closed the breaker, pulled the switches, and turned the breakers back on, testing both switch boxes for voltage.  There was voltage at both boxes, but light did not function.  Pulled the light fixture and tested for voltage:  confirmed.  Closed breaker.  Pulled wiring from switch one, and reattached to new switch.  Pulled wiring from switch 2, reattached.  Turned the fuse box back on and light worked.  End of project.  Today she called me back and said the switch did not work.  I went back and tested, and sure enough, no light.  I went to the other switch and tried it, and the light came on.  Returned to other switch and light worked.  Depending on how one switch was set, the other might or might not work.

I pulled all the switches, and the light fixture.  She decided since I had it open she would like to replace the old one.  After a quick trip to Lowe's, returned with new fixture.  All wires are unconnected from anything, except the two sets that are soldered.  I test for voltage, and the black from one set in the ceiling box is hot.  No other wires test hot.  I assume that this set powers the light which the two switches control. 

I can't get the darn thing hooked back up and working.  I googled and I think the wiring diagram should look like this:




But they had the white from the first set wired to the black from the second set.   If it is powered from the first set (it has the hot wire when the breaker is on), then the black from set 1 should be connected to the white from set 2, and that white wire would be relabeled as a black.

Any ideas?

[dug]

I'm assuming that at one time this setup was working O.K.?

The diagram you posted looks right to me so your situation as described with incoming neutral connected to black seems backwards, hot should go to white remarked as traveler. Are the black hot wires are hooked to the black common screw on switches and travelers connected to silver screws?

[Native_NM]

Thanks, Dug.

The light worked fine for years until it just stopped abruptly.  There was no warning or indication of a loose wire or short.

I agree that it seems backwards.  If those two sets were not soldered and taped together, I might think I had switched them or just got something wrong.  As I pulled things apart I carefully diagrammed everything.

The old switches did not have colored screws or markings, which complicates things. 

The new switches have a black and two copper (traveler) screws.  I am going to buy up a tone tester today, and see if I can confirm that that the wiring is consistent with my understanding.  There may be another box or hidden J-box I'm not aware of.  The distances between all the boxes is short enough that I may rig a quick continuity tester up instead.  Nine volt and some alligator clips. 

If I can't get it, I'll call the electrician.

[NM_Shooter]

The fixture is hot all the time when the breaker is on???  So the original design has the neutral switched?  Yikes.

Hmmmm....

I had a similar problem with the wiring at my in-law's house. 

If you get completely stuck, try this.  Power off, disconnect all wiring.  Use an extension cord and a continuity tester to identify and label all wires in all boxes.  Once you know exactly which wires are which, draw a schematic and go from there.  It is a PITA, but it will get you through it. 

Good luck!

[Tickhill]

Houses wired before the 60's stand a good chance of breaking the neutral in a switch leg. If the insulation jacket on the wiring is fabric, then I assume neutral switching until I prove otherwise.

[handyman]

I would try rearranging the wires on the three way switch until it works.  Different switches have different combinations, at least thats what I have found.

[Native_NM]

I ended up using the "extension cord" method of determining continuity between the wires.  I marked everything,  cut everything back, and started from the diagram I posted.  Removed the old soldered and taped connections.

The insulation is fabric, and I assume it was wired with a neutral break, as there was no other way it could have worked before.

Thanks for all the advice gang.