strange switch feed wire issue

14 years ago

A tenant reported that a light was out in their apartment. I removed the switch and used a home-made test light to check for power to the switch. There wasnÂt any. I then went to the basement to track down the feed wire that was leading up into the bedroom. I found it and followed it to the junction box. I tested the feed wire to the junction box to make sure it had power and then reconnected the line. I then went back up to the switch and found that my test light lit up twice, but not again. I also noticed little sparks as I used the test light and rubbed the wires along the exposed switch wires. The circuit breaker does not trip.

I used the test light in another location after I checked the switch (to make sure the test light still worked). I thought that the exposed portion of the switch feed wires were corroded? so I scraped them and I was still unable to get the test light to light up. I did see the tiny sparks occasionally again though.

Any ideas?

Comments (9)

mike_kaiser_gw
14 years ago
When you used your test light did you go hot to neutral or hot to ground?
treefrog10
Original Author
14 years ago
As I always do, I hooked up the white to the white and the black to the black. So would that be neutral to neutral and hot to hot? The test light is a closet light bulb and I have used it a number of times.

Thanks for the reply...I am assuming this may be a ground issue??
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Billl
14 years ago
Is the switch part of as switchloop?
treefrog10
Original Author
14 years ago
The bedroom contains two outlets that work even when I disconnected the supposed switch feed wire from the junction box. This isn't surprising because most outlet and switch circuits are separate. I also checked the adjacent room switchs (lights) when I have disconnected the supposedly wire that goes to the problem switch. All those lights still work, so I think this switch wire is dedicated for the problem switch.
normel
14 years ago
Check the light bulb?
treefrog10
Original Author
14 years ago
If there is, seemingly, intermittent power going to the switch, then wouldn't the light bulb not matter? My test light IS the light bulb. Don't forget, I have disconnected the switch and I'm checking the wires feeding the switch.
Billl
14 years ago
"A tenant reported that a light was out in their apartment."

You need an electrician. You should not be attempting this work yourself.

Just for mystery's sake:

How many wires are in the switch box? 3 or 6? If 3, that white is not a neutral but leg of a switchloop. To use your test light to see if power is getting that far, you would connect 1 end to the black and the other to ground. If that lights up, then the problem is likely at the light fixture.
mike_kaiser_gw
14 years ago
Treefrog,

If your test light works hot to ground but not hot to neutral, that would indicate a problem with the neutral somewhere. If neither work, it would indicate a problem with the hot.
groundrod
14 years ago
Take normel's advice and change the bulb in the fixture. You probably have a switch loop, and with a bad bulb in the fixture it will not light your test bulb.