I have a (normal?) light/fan combo, which I have not previously investigated. It was controlled by two wall switches, one each for light and fan.

Recently, the light stopped working (off, and switch position did not change anything). The fan continued to work normally. After going through normal steps for diagnosing the light (replace the bulbs; check the pull-chain, etc). I pulled the fixture down.

There are four wires coming in to the ceiling box: white, red, black, and bare copper. None are currently connected to anything.

Copper is obviously ground. White and red appeared to be connected to the fan as hots, with black as a common return, though I'm not 100% certain of the fan connections.

So far, that's normal. Here's the problem:

Each switch currently makes white AND red hot (non-contact voltage detector). White and red are not shorted together (multimeter reading) when the switch is off. I have not tried measuring anything else.

At this point I have stopped messing with it while I try to figure out what's going on. What are my next steps?

I pulled the mount to get at the fan box. As expected, it's just a cable coming through with the four wires described.

The switch box is more exciting. It looks like it's doing double-duty as a junction box? The large white bundle appears to be where the white wire connects (?!)

inside fan box inside switch box different view inside switch box

Re-applying power, the left switch applies a voltage of 120V across Red-White...and also puts about 40V across Black-White. Right switch alone puts 120V across Black-White and about 40V across Red-White.

  • 2
    Can you post photos of the inside of the ceiling fan box please? Jul 31, 2022 at 16:55
  • 2
    Would turn off the breaker and take pictures with switches pulled out
    – crip659
    Jul 31, 2022 at 16:55
  • This getting odd. You have a red at the ceiling, but the red at the switch is short and connects to a black. Should have another junction box between the switches and the fan to get the red.
    – crip659
    Jul 31, 2022 at 18:31
  • @crip659 sorry, hard to tell in 2D, but no: there are two red wires. Look at the paint-covered one from the top right: that's the one that connects to the switch. There is another red wire behind that just happened to exactly match up in this photo with where the front red wire is painted.
    – fectin
    Jul 31, 2022 at 18:36
  • @crip659 added another picture to try and make it clearer.
    – fectin
    Jul 31, 2022 at 18:42

1 Answer 1


It was all mass hysteria, or something.

I had an actual electrician come in and looked at the wiring; it's fine. He was also confused by the mass of other wiring in there, especially the red-black junction, but deciphered enough to say it's all correct. The problem was in the fan after all. There was a component (current limiter?) that burned out.

I am not at all clear why I was getting voltage readings on lines that should be dead, but @nobody's comment suggesting inductance is now my best guess.

Fan is repaired and working again, so all's well that ends without a housefire.

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