How to … 3 way dimmer & 2 on/off switches


I recently replaced a 3 way rotary dimmer that has 2 on/off switches on the same circuit.  Before the dimmer stopped working I was able to switch the lights on/off with the dimmer and either switch.  Now that I have replaced the dimmer, I can’t do that.  Once I switch off the lights with the dimmer, I can’t switch on the lights with either switch.  When I replaced the dimmer the old dimmer had 2 black and 1 red wire while the new dimmer had 2 red and 1 black wire.  Looking at the back of both dimmers I could see that each had 1 black and 1 red coming out of the same hole and the other red/black wire coming out of a different hole.  Also .. on the new dimmer it had a tag (saying don’t use if single pole) on the red wire coming out of the same hole as the black wire.  I tried to swap the 2 red wires on the dimmer and that didn’t change anything.  It must be a wiring thing as I get the impression the dimmer is working like a single pole and not a 3-way.

Thanks in advance for your help.

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Al Sillito 2 years 5 Answers 484 views

Answers ( 5 )

  1. Yeah  I would say so. Ok the wire that says only use if 3-way, that would be your traveler. Now what’s what is hard for me to say without being there. But now you had said the old wasn’t working either right?

    Ya know one of the other switches could’ve gone bad. Watch my videos on how to install a three. This should help you figure out what’s what..

    How to Wire a Three Way Switch to a Existing Single Pole Light Switch Circuit.

    How to wire a 3 way switch with video

  2. since the red wire (next to the black) had a tag saying only use if 3way, then I have to assume that is the traveler.  Using a meter how can I tell what wire is what ?

  3. If in fact the new switch is a 3-way you’ll need to read the instructions that came with it to what those wires are. Wich one is the traveler?

  4. yes … replacing a similar switch that stopped working.  The old switch had 2 black wires and 1 red, while the new switch has 2 red and 1 black.  On the old switch the red & black come out of the same hole and the other black comes out a separate hole.

  5. Is the new dimmer a 3-way dimmer?

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