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I am replacing an old (1980s?) ceiling fan with light. The light and fan were turned on with one wall switch and pull cables on the fan. I pulled out the fan fixture and found wiring in the box that I am trying to understand. My primary purpose is to leave the circuit wiring safe while I find a new fixture (and then ultimately to wire the new fan correctly).

In the ceiling box I found three cables, each with three wires (1 black, 1 white, and 1 copper). The 3 copper wires from these cables are all pig-tailed together, and so are the 3 white wires, the black wires were attached to the fan/light wires. I think what is going on is that one cable is the feed to the box and the other goes off to the rest of the circuit.

I pigtailed the 2 black wires from these cables together and everything in the rest of the circuit seems to work. I tested the wires and the white pig-tail is not hot and neither is the copper ground pig-tail. My black pig-tail is hot, but the final black wire for the third cable is not hot.

I think the final cable may be for the switch loop. However, based on everything I've read, it sounds like the white wire from the switch loop cable should be marked black because it would be switched hot and should not be pig-tailed to the other white wires (but it was and everything worked for many years?). What am I missing??

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    Whites together, grounds together - good. A little confused about the description: Before you made any changes, what was EACH black connected to? – manassehkatz Dec 31 '18 at 23:44
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Whites all together with a switch loop, that's not good. It means you are switching neutral. Power is going

  • from the 2 black wires (supply and onward) to the fan's hot...
  • from the fan's neutral to the switch via the black wire
  • and then from the switch to the neutral bundle via the white wire.

That is bas-ackwards and was wired by an amateur.

First, the switch loop cable must be identified and both ends of the white wire marked with black tape, per Code. Also, this white must be used as always-hot, per Code. This is why: electricians are expected to test wires, and by making white always-hot, it will clearly test as hot every time. Otherwise if the switch is off, it will test as not hot, and could be mistaken for the usual hot-neutral pair. There was once a rule that white wires didn't need to be marked if the usage was obvious, but you just saw how it isn't obvious even in a simple situation.

I for one am a big fan of marking switched-hot wires with red tape, so I'd mark both ends of the switch-loop black with red tape, while I was in there. Also the black wire on the lamp itself.

Switch-loop black and lamp black (the ones I'd mark red) go together.

The remaining blacks are supply and onward power. They go together with the switch-loop always-hot (white tagged black). The remaining wires are all white, they go together.

  • Your answer sounds quite plausible - though it means a really messed up original wiring. That's why I was trying to find out the original configuration - which is likely lost forever... – manassehkatz Jan 1 at 18:06
  • I just saw this post and think that must be what is going on - it was a very old fan and clearly not installed to code. Thank you both for your answers and for telling me how is should be wired. – amys Jan 1 at 18:18

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