So I took off a broken chandelier and wanted to replace with a simple flush ceiling light. When doing so, I found two black and two white connected properly, but found a lone white wire that was covered by a twist-on. What would this be for? The chandelier never worked after I moved in so I'm not sure. Also, note that the fixture was connected to a rotary knob (dimmer).

Anyway, I wasn't sure what it was for so I attached the lone white to the other two. Now when I turn on the breaker it trips. What would it be for? Thanks!

  • Can you post a photo of the inside of the ceiling box? Aug 11, 2018 at 14:25
  • You should get a non contact tester to see what is hot and switched hot. The ceiling outlet might have been originally wired so that two "3-way" switches controlled it, then someone "messed with it". Is the switch that controls this a standard on-off or is it a 3-way (bare toggle with no "on" and "off" printed on it)? is there another switch on another wall that does nothing when flipped? google.com/… Aug 11, 2018 at 15:33
  • @JimStewart Funny thing is, after I replaced the fixture I went to press in the dimmer switch to turn it on and it broke too, so I had to go buy another which I will try later with the lone wired detached. But I was thinking the same, it must have been for a 3-way at some point, because none of the current other switches control it.
    – Zach
    Aug 11, 2018 at 16:15
  • @ThreePhaseEel I'll try and get a picture/video later if I have any further issues, thanks.
    – Zach
    Aug 11, 2018 at 16:15

1 Answer 1


First never attach unidentified conductors until you identify what it is (standard service electrician training). The lone white conductor that was isolated could very well be a switch leg or a non neutral conductor. It should be identified by a phase tape (black, red or blue tape or some other method), but this isn't always done.

So take the lone white wire off of the neutral, cap it off and leave it alone. Then see if they lighting circuit is working properly and make sure no damage was done by connecting it up. If not knowing what that conductor is for is really bothering you, then trace it out or hire a professional to inspect and identify your circuits and make any corrections as needed.

Good luck and stay safe.

  • Yea, it was a pretty dumb thing to do. I thought it had something to do with the dim, but who knows. I'm going to remove it later and try it out. I always shut the entire house off when doing anything electrical. Thank you!
    – Zach
    Aug 11, 2018 at 16:12
  • So I ended up removing and re-capping the spare white and now the fixture is constantly on... any ideas why? The light switch does nothing.
    – Zach
    Aug 12, 2018 at 0:38
  • Did you burn out your dimmer? If you have a non contact indicator it should be a fairly simple task to check it out or you can use a voltmeter. Aug 12, 2018 at 1:50
  • Disregard! I know, I thought the box was toast, but turns out there's a little dial on the left side of the switch I had to adjust to set the start point. Thanks!
    – Zach
    Aug 12, 2018 at 1:53

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