I have no issue troubleshooting 3-way switches but this is an odd one. At some point a handyman replaced switches and messed up a 3-way switch setup. However it's 2 lights and 2 switches: - light A and switch A at top of stairs - light B and switch B at bottom of stairs I want both switches to control both lights simultaneously. However, the way it is now: - switch A controls both lights fine - switch B only turns on/off light A, has no effect on light B

Switch A has 3 regular leads: red end which is connected to one traveller terminal, white end which is connected to the other traveller terminal, black wire connected to the black screw but then continues to another switch for an outside light so this appears to be the hot. Then there is an additional end of another black wire. This extra black wire controls light B and seems to be the key to the problem. If I touch it to the hot wire, then light B turns on as expected, if I attach it to either traveller screw, then light B turns on and off with switch A. I'm just not sure what I can do to make light B also turn on and off with switch B.

I've most combinations and nothing seems to get both lights working with both switches. Maybe I'm missing a white wire to light B in the mix somehow?

Thanks for any troubleshooting tips you may be able to provide.

  • 2
    Can you provide pictures of each switch box and verify the hot feed?
    – JACK
    Apr 7, 2020 at 17:00
  • Because you can't do that with the number of wires available in most 3-way circuits. Now if the last guy used a /4 cable, then yes; however random "last guys" almost never use /4 cable. Your concept of powering lamp B from switch B is utterly bankrup--- hold on. This just in. Smart switches are now on the market, and may open up this option! Apr 7, 2020 at 17:20
  • 3
    Also stop "trying combinations". There are many combinations which will work and will kill you. If you don't know why you're doing something with electrical, stop and learn. Only act with knowledge. Apr 7, 2020 at 17:24
  • 1
    @Harper-ReinstateMonica I knew "trying combinations" would get ya...
    – JACK
    Apr 7, 2020 at 17:43
  • 3
    I'm not talking about while you're working on it, I'm talking after. And yes, 120v can and will kill you, I and it don't care how many times you've been lucky in the past. If you are cavalier you should stop. Apr 7, 2020 at 18:52

1 Answer 1


I figured it out, once I had both switches out of the box and pulled out all the bundled wires it was easy enough to figure out where everything was going and what was going on based on what was working, there was a hot circuit coming in, circuits going out to each light, and the 3-way circuit going between the switches, so it was easy enough to identify the lines running to each light and put them in parallel. Cheers.

  • Thanks for reporting your results. We're glad to hear both that your lights are working, and that you're still alive. Apr 8, 2020 at 3:08
  • Good, sounds like the person who wired it, wired it properly... with both lamps from the same switch box. That was not what was described in the question, hence my concern. Glad it worked out for you! Apr 8, 2020 at 4:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.