Not sure how best to word this without getting tedious. But this old house is such a pain. Basically I am trying to figure out how to rewire a light switch in a bathroom that used to control two separate bulbs on a bathroom ceiling. These lights were part of a recessed fixture that was part of an exhaust. The exhaust was on its own power supply and the two switches controlled two bulbs.

I hope the pics I took come through and that you can see them. The black wire from the Romex in the upper left hand corner is the only one that is hot (I used a voltage tester to confirm this). The Romex on the upper right and lower right don't activate my tester.

Not sure what other details I can provide. When the wires are all disconnected but the power to the circuit is "on" the black Romex at the ceiling is also hot.

Can anyone tell me how to rewire this so that I can get the light on the ceiling working? What was previously in the ceiling were these two recessed light bulbs that were controlled individually by two light switches which I removed and is what you see on the wall now. And now all I want to do is use one light switch to turn on one light fixture that I centered in the ceiling (pic provided).

Not sure if this is necessary but there is another light switch above the exposed plate in the photo I've provided. That one I can get to work but it will be designated for the new exhaust I will be installing that won't have a light fixture. wall switch

Last bit of possible useful info. The gauge of the Romex located in the bottom right hand corner of the switch box is noticeably smaller so I wonder if that was to control the second light which I am no longer using.

enter image description here

Hope to get some input, thanks.

  • 1
    Looks like you’ve got one hot coming in, and two cables going out - one for each of the original lights. As one of the cables going out is smaller gauge than the other, does the cable in the new light match the larger one, or the smaller one?
    – Mark
    Jan 17, 2018 at 23:42
  • Hope I understand your question. It looks like the Romex wiring is larger for the cable in the ceiling that is running to the new light fixture. In the switch box the Romex appears to be the same size in the upper left and upper right hand side. The lower hand Romex in the switch box is very thin and looks a lot different.
    – Adrien
    Jan 17, 2018 at 23:51

2 Answers 2


You determine which of the two cables on the right is connected to the light.

Turn off the breaker to the line hot (cable on the left). Fasten the line hot to one pole of a simple switch, and fasten the black from the candidate cable (say the upper one on the right) to the other pole of the switch. (Keep the whites out of the way for the time being.)

Turn the breaker back on and use your non-contact voltage tester to see if the black at the lamp is powered when the switch is on and unpowered when the switch is off. If it is, then go turn the breaker off and connect the white in the line cable to the white in the cable whose black is connected to the switch. Now turn the breaker on and the switch on and the light should come on.

To complete the job go turn the breaker off, fold the wires, and screw in the switch. Cap the wires to the other cable which is not going to be used. Put on a cover plate. Turn the breaker on and verify operation.

NB: You should really verify that the cable you have energized goes only to the light and not also to some other cable that should not be powered.

  • Thanks for responding but I am confused. Mind if I word it my way and you can let me know if I am understanding you correctly? I'll do it in steps: 1) Turn off breaker. 2) Connect black hot wire to simple switch. 3) Turn breaker on to test if voltage tester activates at ceiling lamp fixture. 4) If yes, turn breaker off again and connect white wire from upper left to white wire to upper right (in photo). 5) Turn breaker back on and light should come back on. 6) If all goes well, turn breaker back off, fold wires, cap wires that are not being used, install cover plate and turn breaker back on
    – Adrien
    Jan 18, 2018 at 0:26
  • Update! I figured it out thanks to your instruction. Guess I understood you after all. I am SO grateful, Jim! Thank you THANK YOU! This was perplexing me all day. You are the best!!
    – Adrien
    Jan 18, 2018 at 0:52
  • 1
    Adrien, on a site like this you thank by simply marking the answer as "accepted." Jan 18, 2018 at 0:58
  • Still one question - what did you do with the end of the cable in the ceiling that connected to the other (unused) old light fixture?
    – Mark
    Jan 18, 2018 at 1:09
  • That is a good question. I was so focused on what I was trying to do that I didn't even pay attention to that. After reading your question I went to go look and I don't know where there are any other Romex cables. There is only one more that I mentioned that is on a switch above the ones I took a photo of. I didn't tuck it away anywhere. I honestly don't know. The person who sold my partner this house did the work and did a crappy job on everything. To give you an idea, a circuit in the basement controls rooms on different floors but on the same side of the house. That's how bad it is.
    – Adrien
    Jan 18, 2018 at 5:13

The most puzzling part about this situation is the statement, "When the wires are all disconnected but the power to the circuit is "on" the black Romex at the ceiling is also hot."

That can only indicate that there was originally a switch loop involved, which naturally implies that there had to be another Romex pair in the original light fixtures. You need to involve that set of wiring and it must necessarily be the opposite end of one of those sets of wires from the switch box.

  • Thanks for catching that. I actually was wrong when I typed that up. When the Romex wires were disconnected at the switch plate the black Romex at the ceiling wasn't hot. I made an error when I first typed up my query.
    – Adrien
    Jan 23, 2018 at 1:37
  • @Adrien You should edit the question to reflect this update. It's equally confusing to future readers
    – Hari
    May 4, 2018 at 18:03
  • I'm sorry. What do you suggest I provide in the question title as a way to update it?
    – Adrien
    May 8, 2018 at 1:56

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