I have a dead ceiling fan I'm trying to replace with 4 recessed lights. I took it down to find it has a 12/3 cable run to it, and a 12/2 cable run from it (I thought it was the last device on that run). The 12/3 is all on the same breaker.

The black conductor was constantly hot and provided power to the porch light and apparently 2 outlets in my bedroom. The red conductor was controlled by a switch in the dining room for the fan.

Unfortunately the fan was in a terrible place and the 12/2 isn't long enough to reach where I need it to go. My question is:

Can I replace the fixture box with a steel junction box, and run two 12/2 lines from it. With Switched Red/Neutral/Ground running the 4 lights, and the Hot Black/Neutral/Ground powering the 2 or 3 things downstream?

Here's a quick doodle:enter image description here

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    Same two pole breaker? Why do you want to change the box instead of just putting a cover on it? Commented Dec 16, 2019 at 0:05
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    I thought about a cover but It's off center in the "middle" of the dining room ceiling. I'd rather put it in an attic-accessible junction box and patch the hole
    – Xhynk
    Commented Dec 16, 2019 at 0:13
  • Could you take a picture of the breaker? Commented Dec 16, 2019 at 0:14
  • Assuming yellow = white (since white won't show on white background) and green = ground, any new drawings leave out the ground since all grounds connect to each other, to receptacles, etc. so they just add visual clutter without adding extra meaning (but always connect them!). Commented Dec 16, 2019 at 0:35

2 Answers 2


You don't even need to replace the fixture box. Fixture boxes are allowed to be junction boxes. Boxes are a PitA to change anyway, because of the risk of damaging the cables and the close quarters. They make blanking plates for unused ceiling boxes.

Also, presuming the box is a fan box, you may want to leave it intact, in case the next owner wants a ceiling fan or a light there.

A Multi-Wire Branch Circuit is fine as you draw, as long as the /3 cable lands on one breaker whose handles are factory-tied together, or two independent breakers with a field-installed handle-tie that is UL listed for the breakers. There are a few other requirements for MWBCs, but they are irrelevant to your plan.

  • If I don't replace the fixture box, won't I need to use a cover plate - Not exactly ideal in the middle of the ceiling lol. Also after a bit more back tracing I found the /3 actually originates from a /2 at the breaker, and the splits in the /3 at the first junction box - like the did it so they only had to pull one wire instead of two /2 wires. I'm effectively just replacing the fan with 4 recessed lights, but adding a /2 wire from the j-box because the original wiring isn't long enough
    – Xhynk
    Commented Dec 16, 2019 at 0:47
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    @Xhynk What!? You can't bury the box!!! Do you understand that? The box cover must be accessible forever. There is no way to have a smooth ceiling unless you entirely remove all cables going to it. OK, so the red wire is not a MWBC, just a switched-hot for the light or fan. Commented Dec 16, 2019 at 0:54
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    This box has attic access, so I was wondering if I could replace it with a steel octagonal box with the cover plate facing in the attic. Is that not considered accessible? Also yes, that's correct - the red is just a switched conductor for the fan, the black runs through that same box into the next fixture (porch light)
    – Xhynk
    Commented Dec 16, 2019 at 0:59
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    Yes. you can run to the new lights. If it were me and it only came off one leg of a breaker I would only use the black for a hot, and insulate off the red at all locations just to insure that nobody ever inadvertently gets into a hot or connects to a hot wire with the neutral disconnected. Commented Dec 16, 2019 at 1:10

It is legal to have two hots fed from two separate legs from the electrical panel, it creates what the code call a Multiwire Branch Circuit. The hots can separate any time after the first junction box, and go different directions. For about 15 or 20 years now the NEC has required that the handles from the two circuits be handle tied and in the panel there are some wire grouping or marking requirements.

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    It actually looks like the 12/3 doesn't actually go all the way back to the breaker. There is 14/2 coming from it to a box in the kitchen. From there, the 12/3 is run to the switch/fixture I mentioned. So it looks like the just ran the 12/3 so they only had to pull one wire up there. What I'd like to do is basically the original configuration, but would add a 12/2 wire in the junction box to run the 4 lights instead of running the fan/light directly off the red/neutral. I can try and get a few more pictures if that would help
    – Xhynk
    Commented Dec 16, 2019 at 0:30

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