Took down a ceiling fixture and discovered what looks like a possible switch loop, except I don’t understand how the connection gets completed with the current set up. Basically, 2 lines coming into the fixture box. The black from line A is wired to the fixture, and the white from line A is essentially “capped off” (is cut short and contained within the insulated portion of line A). The white from line B is wired to the fixture, and the black from line B is capped off. Over at the single pole switch there is a black wire and white wire attached. This would make sense to me as a switch loop if the 2 capped off wires were joined together, but they’re not. enter image description hereenter image description here

  • Do both cables (A and B) from the fixture run to the switch? – mmathis Jan 29 at 14:21
  • I think it’s probably indicative of a repair at sometime in the last XX years where a wire became broken or unhooked. The result is not to code, it’s not correct, but it works. The problematic safety issue is whether 2 circuits got combined executing “the fix”. – Tyson Jan 29 at 14:26
  • You can't say it is not to code as you don't know when the home was built. – Ed Beal Jan 29 at 17:46
  • @EdBeal I'm pretty sure the rule predates the existence of white Romex. Looks like someone had a problem with their black wire in the old black Romex, ran a new Romex, decided they only wanted to replace the black wire so they nipped the white off and continued to use the white from the old Romex. Not a great plan. – Harper Jan 30 at 0:11
  • Do both cable A and B make it back to the switch box? – Stanwood Mar 21 at 12:40

That's bad.

The white and black should be used in every cable to prevent electromagnetic induction.

The only single conductor you should ever have in a residential electrical system is a ground wire.

You need to investigate this and correct it.

It looks to me there was a problem and someone just capped what they thought to be the hot. One cable should have the hot and neutral the other goes to the switch connect the hot to the white going to the switch the black coming back from the switch to the black of the light fixture, white to white and connect the grounds together. This was the code compliant way to wire switch legs a few years back, now the neutral has to go to the switch box but this dosent need to be updated for a repair or fixture replacement.

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.