I have a very old house with unknown wiring, two ceiling light fixtures in the living room, and a very strange problem with the lighting in these fixtures:

When I turn on the first LED ceiling light via its pull-chain switch it works as expected. But when I turn on the other LED ceiling light via its wall switch, the second light turns on as expected -- but at the same time the first light gets BRIGHTER.

If anything, I would expect that turning on the second light would cause the first light to get dimmer (due to the added resistance) but this seems to be incorrect. Can anyone tell me what might be going on here?

  • 1
    Does one light have to be on for the other to turn on? Sep 18 at 23:47
  • 1
    Does the "second light" in your question act the same way if you turn on "the second" first, and the first, second? i.e. if you switch the order of turning them on, is the behavior the same (that the light first turned on gets brighter when the next light is turned on?) So, Wall switch, then Pull chan, what happens?
    – Ecnerwal
    Sep 18 at 23:47
  • Yes, when I turn on the light controlled by the wall switch it turns on somewhat dimly, then when I turn on the pull-chain light it lights -- and the wall switch light gets brighter. Sep 19 at 0:43
  • So basically whichever light I switch on first will light, but it only lights dimly -- until I turn on the other light -- then they both seem to get "full power" and are brightly lit. I also noticed that when I turn one light off (and it doesn't matter which one) the other gets dim. It's almost as if neither light is getting "full power" unless they are both switched on. Sep 19 at 0:49
  • 1
    Are you using screw in LED bulbs or are there actual LED fixtures using drivers to power the LEDs?
    – RMDman
    Sep 19 at 0:55


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.