I am upgrading a bathroom fan from below (no attic access) and replacing the single pole switch with a timer switch. I’ve wired switches and outlets before, but this one is throwing me for a loop. I don’t trust how it was wired before, and I’d like to do this correctly. Romex 1A and 1B were formerly a single 12-2 Romex that ran power up to the attic to some outlets. When the previous owner redid the drywall in the bathroom, they put in a poor-quality fan (w/ a light) where there wasn’t any fan before. They powered this new fan by cutting that wire (Romex 1) running to the attic and tied it together in a junction box above the ceiling. Then they ran 12-2 down from the new junction box to a new single pole switch. Then they connected the whole thing in a big mess with pig tails….but it worked. Of course, the light and fan came on together which is fine with me.

Romex #2 is stapled behind the drywall, so I can’t use it to pull a new 12-4 cable from the timer switch to the fan. And I haven’t been able to fish my tape down from the fan opening to the switch. I really don’t want to cut holes in the drywall to fish 12-4 if I don’t have to.

Update: as ThreePhaseEel pointed out below, I will either need to somehow install 12-4 (in place of current Romex #2) or downgrade to a more simple timer (or single pole switch). If I simply put back in a single-pole switch for now (instead of the timer shown in the photo), then how would I connect everything up at the light to allow the attic outlets to still have continuous power? I’m OK with having the light and fan come on together (it’s an energy efficient LED light and fan). I tremendously appreciate any help.

bathroom ceiling fan wiring diagram

  • Actually you'd need to run 12/4 not 12/3... since this is a new cable you'd have to include a neutral wire along with your hot and 2 switched hots. Apr 15, 2017 at 5:50
  • Thanks @Harper. I have edited my response to reflect your helpful (and accurate) suggestion.
    – Jason
    Apr 19, 2017 at 6:53

3 Answers 3


how would I connect everything up at the light to allow the attic outlets to still have continuous power?

Wire neutrals #1, #2, and #5 together; there will be no neutral connection to Romex #2. Connect "black" #1, #2, & #3 together, to deliver power to the outlet in the attic and to the wall switch; #3 will connect to the "line" terminal on the switch (if it has a terminal labeled as such, most do not and it doesn't really matter).

The wire you have labeled as "neutral #3" in your diagram will actually become the "switched hot" that delivers switched power back up to the load (to black #5 and red #2), if it is a white wire then you must mark it as a switched hot by wrapping black or red tape around the visible insulated ends in each junction box, or marking those ends with a black or red marker, or labeling them somehow.

  • What does he do with neutral for the timer? Or are you saying don't use a timer that needs neutral? Apr 15, 2017 at 5:51
  • Ha can't use a timer that requires a neutral unless he pulls new wire. This answers the "update" section of his question where he says he will put a single-pole switch back in. Apr 15, 2017 at 13:34
  • Ah, yes! Thank you @Jimmy Fix-it for that very clear answer. I'm not only going to flag the 'hot' neutrals, but I will label the wires and leave a wiring diagram up there in the ceiling for the next home owner to discover.
    – Jason
    Apr 17, 2017 at 15:33
  • Worked like a charm! Had to cut the drywall opening (and some wood above that) to a larger size, and had to install a junction box above the ceiling, but I got it done. Thank you again Jimmy Fix-it.
    – Jason
    Apr 19, 2017 at 6:56

Get a different timer

You'll have to take your timer back and get one that doesn't require the neutral to work, unfortunately. You'll also need to make sure your timer is rated for a fan load (many are not).

If you are using a single pole switch instead of the timer -- connect one terminal to the black in the switch box, the other terminal to the white in the switch box, tag the white as a hot with a tape flag, and connect the green grounding screw to the ground wire in the switch box, assuming the box itself doesn't need grounding as well. If it does need grounding, you'll need to pigtail the ground from the switch together with the box ground and nut them to the ground wire. Then, you can wire the box in the attic as Jimmy Fix-It's answer describes.

  • Thank you ThreePhaseEel. I improved my question thanks to your comment--thank you very much. The current timer is rated for a fan load (good call), but what if I just downgraded the timer to a single pole switch for now? Is that simple enough to wire?
    – Jason
    Apr 14, 2017 at 14:26

Why not use the classic spring operated timer switch? It doesn't need neutral to get its own power, it runs on you power! Then you can wire it as Jimmy recommends.

I hate those digital timers, the UI is rather confusing. Why seven switches for a simple function?

You may also be able to find smart switches with in-fan modules they communicate with over the power lines. Then you would just wire always-hot and neutral to everything, the fan and light to the module, and yer done.

  • Excellent, thank you @Harper. I think that's exactly what I'll do (install a simple timer switch).
    – Jason
    Apr 17, 2017 at 15:36

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