wires at one of two lightsElectrical outlet for the switchRecently a dimmer for my basement light was burned. It created a lot of smell so I took it out and threw it away immediately and I don't remember how it was wired.

Now I want to replace it with a simple switch. This is easy if there are two sets of wires, one supply and one going to the light. But mine is very weird.

I see 3 wires at that box, 1 black, 1 white, and 1 bare copper. My electrical test pen makes noise when it touches the black and bare copper, but not white. There is 110V between black and white, and none between black and bare copper or between white and bare copper.

Is is normal ? How do I wire the new simple switch?

Thank you very much.

Update: It was working before the dimmer died. That is the only switch. Today I took out the lights ( that switch controls 2 lights ). Suddenly there is no voltage between the black and white anymore. The electrical pen beeps when it touches any of the wires, even at the black wire at the light. Is it normal ?


  • Was it working before? Because that sounds as if it was never wired correctly and that may be why your dimmer burned.
    – JRaef
    Apr 20, 2020 at 19:04
  • "I took out the lights" ?? Removed them from the wiring ? Did you document how things were wired this time ? "Suddenly there is no voltage" "electrical pen beeps when it touch any of the wires"
    – Alaska Man
    Apr 20, 2020 at 20:03
  • To Alaska: The wires connect to the lights (again there are two at different locations!) in a straightforward way: black to black, white to white, and copper to what it is supposed to. Apr 20, 2020 at 21:24
  • Can you post a photo of the inside of the box please? Apr 21, 2020 at 0:13
  • I just added some pictures. Thanks. Apr 21, 2020 at 14:27

1 Answer 1


Well, you've learned one lesson: always make a drawing (or photo) before dismantling anything. In any case, one hopes that the bare copper is the ground connection. It's pretty scary that there's not 110V from black to bare - this suggests someone ran 2-wire+ground cable and never connected the ground at the far end. I would have a licenced electrician check this out.

responding to update

If this is the only switch, and there's truly 'hot' voltage coming from the light fixture, you have bigger problems. The switch should always be on the hot feed side; as it stands now the switch appears to disconnect neutral but that leaves the fixture boxes with live voltage all the time, and that's a significant safety risk.

The white probably is the feed to the light fixture, since that presumably continues on to the neutral/return on the other side of the fixture.

Make sure this is the only light switch that controls this fixture, rather than being part of a pair of 3-way switches, in which case everything I suggested may not apply.

  • @george Anderson combine your 2 comments into an answer as that is the only code compliant possibility.+ Carl the OP is using a tic tester or non contact tester not a volt meter.
    – Ed Beal
    Apr 21, 2020 at 6:43
  • @EdBeal I removed my comment bc there are just to many unknowns now....see OP's pictures he added a bit ago. Apr 21, 2020 at 15:45

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