I recently took off a light fixture in my home's bathroom and before I could take mental note of the wiring situation, the white wire from the fixture slipped from a wire nut (not a great sign of previous electrical work, I know..). The black wire from the fixture was connected to the single black wire on the right side of the box (presumably the switch's cable) but I do not know where the fixture's white wire was connected. I have a feeling the white wire from the fixture was connected to the two black wires on the left side of the picture, however, I'm hesitant to do that (I added the electrical tape for now). Note that the fixture/switch were working perfectly fine. Any thoughts on where the white wire from the fixture needs to be attached? Thanks in advance

Box & wiring

  • Something is amiss. If the black from the fixture was connected to the single black then the only way I can see this working at all is if one cable is hot, one cable goes down to the switch and the third cable returns as switchleg, and they paralleled the neutral between the switch and light. I think the white that is with the sole black needs to be disconnected from the red wirenut, then fixture white connected to that white. If the fixture black was connected to the black pair and white to the black single then you would have a switched neutral, which is a new problem. – NoSparksPlease Feb 13 '20 at 1:14

What you've got here is power in to the fixture box, power out to whatever is next and a "switch leg" cable to the switch. You are probably right that the wires from the fixture were connected to the blacks with the wire nuts. Unfortunately this isn't best practice, dangerous at best. This setup leaves the fixture "hot" all the time and effectively interrupts the neutral.

The way to make it right is to connect the right black wire with the 2 on the left. Disconnect the white wires and code tape black the white wire coming back from the switch. Connect that to the black wire on the fixture and the other wire (white) from the fixture to the other white wires. Best practice would be pigtail the whites so you only have one wire to deal with when installing the fixture.

Oh and get a wire nut on those ground wires while you're in there!

  • You know on a switch loop, the white must be the always-hot... – Harper - Reinstate Monica Feb 13 '20 at 2:10
  • Good catch, I did not know that was the convention. While it's counter intuitive to me, that is the correct answer. OP please take note of Harper's comment. Thank you Harper. – George Anderson Feb 13 '20 at 4:23
  • The reason is so that someone using a voltage tester will always see a white wire which is hot (which should set off alarm bells)..... instead of sometimes seeing a hot black and a cold white, which looks like normal hot-neutral. – Harper - Reinstate Monica Feb 13 '20 at 8:44

Hook the white wire from the fixture to the group of white wires under the red wire nut. The black wire from the fixture goes to the single black wire in the box. It appears that the person who originally wired this used two 12-2 instead of a 12-3 going from the fixture to the switch. I think the NEC frowns on this.

OK, if this is a switch loop, then forget this and go see George's answer. My first thoughts were an attempt to get hot and neutral at the switch location and to switch the light. A picture of the switch box would clarify this.

  • Jack: That's what I would have done (see my answer), but Harper pointed out that, oddly enough, the white wire should from the switch leg should be code taped black and connected to the blacks on the left and also code taped black in the switch box. I researched Harper's comment and found that he was right. I also saw switch legs running /3 and just using the black/red for proper wire colors...not using the neutral at all. But in practice, I've never seen one run that way, is that a recent change? I hate switch loops anyway because there's no neutral for smart devices. – George Anderson Feb 13 '20 at 16:39
  • @GeorgeAnderson As usual, Harper's right but my scenario was even weirder. I wouldn't have even thought about it if I hadn't run into it a few weeks ago. None of the white wires are hot. One of 12-2 brings hot and neutral from ceiling to switch box, black to switch. The other 12-2 , black to switch and two whites connected goes back to ceiling where white it connected to other neutrals, parallel path, and black is connected to fixture and fixture white is connected to group of whites..... no whites hot or switched. – JACK Feb 13 '20 at 18:01
  • @GeorgeAnderson The OP could solve all this with a picture of the switch box. In all honesty, I think you nailed it and my answer is a long shot+ – JACK Feb 13 '20 at 18:07
  • Thank you all for the help on this but I’m still not 100% sure how to resolve. I don’t have a picture of the switch wiring but can confirm a switch loop. There is only one wire at the switch hence the switch loop and the white is running hot. Given that the switch’s white is running hot, shouldn’t I connect the switch’s white wire to the two black wires on the left? I would then connect the fixture’s neutral to the remaining two white wires (actually running neutral). I would still connect the fixtures black to the sole black wire running to the switch. Thoughts? – Robert Feb 14 '20 at 2:41
  • @Robert The switch white wire should be connected to the two black wires on the left and it should be wrapped with black tape at both ends. The fixture white, neutral, should be connected to the two white wires under the red wire nut and the black fixture wire connected to the single black wire. If the fixture has a ground, connect it to the other grounds with a wire nut. – JACK Feb 14 '20 at 3:08

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