I'm trying to replace an old fixture for cosmetic reasons. Unfortunately I've pulled apart the wiring to the old fixture and don't remember how it all connected. The wiring in the ceiling has the above setup. The fixture itself has the standard 1 white, 1 black, and 1 ground wire. I followed this advice...now the light operates from a different switch from before.

I don't understand the underlying wiring so I'm baffled by what's going on.

Edit: here's a photo of the box: enter image description here

The marked black wire is hot - it lights up my tester when I connect it to any other wire when the breaker is on and the switch is off.

  • how was the old fixture wired? ...... why are you replacing the fixture?
    – jsotola
    Feb 15, 2019 at 20:02
  • 1
    How was it wired before? I mean, originally, besides ground, the wires from the lamp only went to 2 places. Can you still identify those 2, or have you torn it all apart? Feb 15, 2019 at 20:10
  • Can you post photos of how the box is wired? Feb 16, 2019 at 0:49
  • @ThreePhaseEel photo added.
    – logert
    Feb 18, 2019 at 15:08
  • @Harper Unfortunately it's all torn apart now & I don't remember how it looked before.
    – logert
    Feb 18, 2019 at 15:09

2 Answers 2


Well, the good news is each cable is unique.

  • The /3 cable is not like the other cables, and there must be a reason for the extra hot. Was this ever a fan/light? It may also be a new style switch loop.
  • The black wire with the white tape is weird (usually it,s the other way 'round) but that tells us that the black, and its partner white, are special. They may be a switch loop, and I would check for that with an ohmmeter after confirming power off.
  • The other /2 cable is plain. I have a hunch it's either supply power, or onward power to another location.

Now, the question is what else is around here? Is there another light? What's in the switch box? Etc.

Also, what else has lost power?

  • This light is in a hallway right outside a bathroom and a bedroom. There's a switch in the bedroom which has never done anything since I've lived here. I checked and it's wired with two black wires - maybe they're intended to go to this light. The switch that I know powers this light has a red coming in the bottom and a black going out the top. The lights in the bathroom have also lost power, and it's the bathroom switch that makes the hall light work when I follow the advice linked to in my original post.
    – logert
    Feb 19, 2019 at 20:32

It's most likely a 3 way switch application. So two switches should operate the fixture. There are a few different correct ways to connect 3 way switches. There are many wrong ways to connect them. Based on the information above, you most likely need to connect fixture black to box red, fixture white to box white and ground to ground. Two switches should operate it. Example top of the stairs - and bottom of the stairs. It's not always the case but the red wire indicates a 3 way application and multiple blacks tied in together suggests that they are the power supply to the switches. Google 3 way switches.

  • The presence of one /3 cable would not indicate 3-way switching. The /3s go between the switches, and would not be seen in the lamp at all (unless the lamp was between the switches, but then, there would need to be two /3 cables present). A solo /3 indicates one (most likely red) is a switched hot. Feb 18, 2019 at 18:24
  • Yep you're right, I'm new to this site and got a little carried away answering some questions without looking close enough. I don't even remember this one. Will be more careful down the road.
    – Joe Fala
    Feb 18, 2019 at 21:18

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