I have a light switch that is installed in a electrical box together with 2 other switches. I'm surprised that the switch has 2 hot wires. One wire is coming from the switch next to it, the other wire is the actual wire coming from the wall. All white wires of the three switches are joined inside the box. Is there a reason why the electrian would install two hot wires for the switch?

  • 1
    Why do you think both wires are hot?
    – brhans
    Aug 22, 2017 at 21:57
  • One hot wire is coming from hot side of the switch next to it, the other hot wire is the hot wire from the wall/breaker box
    – user915308
    Aug 22, 2017 at 22:01
  • 1
    Have you actually measured one or both (and if so, how?) or are you just looking at the colors?
    – brhans
    Aug 22, 2017 at 22:06
  • 3
    Can you post photos of the inside of the box? Aug 22, 2017 at 22:21
  • 1
    There are several possibilities but with all the white wires being connected they should all be on the same breaker. A photo would help us understand your wiring.
    – Ed Beal
    Aug 22, 2017 at 23:30

2 Answers 2


The wire from the other switch is almost certainly the line hot. If so, it will be always hot no matter what position either of the switches is in. This is electrically the same as having a separate wire going to each switch from a common line hot. I have a set of three switches in a 3-gang box wired that way.

The other wire also black should be the switched hot going to a light or a switched receptacle. It would be hot when the switch is on and not hot when the switch is off.


That switch is feeding the other switches.

  • We don't know if there are 3 way switches, or a phantom voltage as some of the possibilities. The site usually frowns on 1 line answers.
    – Ed Beal
    Aug 22, 2017 at 23:32
  • Thanks Ed, but if that is the case why is there another hot wire going to the switch (assumingly coming from the breaker)
    – user915308
    Aug 22, 2017 at 23:48
  • Not all answers require alot of explanation. I could go on to explain how to wire switches, but that wasn't the question. (<-- 2 sentences)
    – NPM
    Aug 23, 2017 at 1:31
  • 1
    @EdBeal As long as it's an answer, it's not low quality. If you don't like it, or think it's not useful, downvote
    – Machavity
    Aug 23, 2017 at 18:26
  • What would be even better, would be if ol' Ed actually provided an answer in the answer section, rather than comments, for once, so users could vote on HIS answers. Afraid of innerweb reputation, I guess. ;) Have a good day.
    – NPM
    Aug 23, 2017 at 22:09

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