I recently moved into a new home and found out one of the bathroom fans don't work but the lights are fine. I thought at first it was the motor but the motor run if i connect it directly to a power socket. I also tested the wires on the exhust fan and they have no current. I tried to understand the wire but I have not accomplished much. Usually there are only two sets of wires but in mine there are four. I have checked other switchs and there not the same there simpler. I have taken a picture so it will be easier to help, i have included a picture what i know or think i know.

  1. Basically the first wire form the left is the form the light.(Black/White)
  2. The second wire is the power line. (Black/White)
  3. Not sure what the third wire is. (Black/White/Red)
  4. Not sure what last one is either. (Black/White)

If anyone has seen this before please let me know.

Labels in the picture.

M-Line : Main power T-Wire : Transferring Wire, this wire provides current to both switch.

Any help would be appreciated.enter image description here

  • Have you checked inside the fan to see if it has a 16/3 or a pair of 16/2s going into it? Both of these switches have two loads coming off of them. Anything else you can find that they might be switching?
    – Comintern
    Aug 7 '14 at 0:57
  • the fan only has a black and white, not sure were this red wire is coming form. So the fan is 16/3. You were right the power outlet next to the switch is controlled by the right switch. were do i go from here. Aug 7 '14 at 1:05
  • Need to see wiring at both fans and light . Is one fan a light/fan combination or is the light separate? Checked for a tripped breaker or gfci outlet? Checked both fans.
    – user24125
    Aug 7 '14 at 1:10
  • I'm guessing the red in the 16/3 goes to half of the outlet, and the black goes to the other half. That would make the 16/2 on the far right the one going to the fan. I'd try attaching the black on that one directly to the main to see if the fan runs that way.
    – Comintern
    Aug 7 '14 at 1:11
  • @Comintern i figured out that the fourth wire is the bathroom outlet, i directly connected it to main to insure its always on since i need it like that and I was sucuessful but i am still stuck on the the set of red and black. where do they typically go. Aug 7 '14 at 2:15

Without actually being there, and not being able to see the wiring at each of the devices, it's difficult to be sure what's going on. But here's my best guess, based on past experience.

Wires labeled

To make it easier, I've numbered the ungrounded (hot) conductors in the photo from left to right.

  1. You've already established goes to a light.
  2. Supplies power to the switches.
  3. Likely goes to the fan.
  4. Also goes to the fan, but since the fan doesn't have a light built in, it's likely capped off at the fan.
  5. Probably feeds some other device, maybe a receptacle.

Why 3 and 5 are controlled by the same switch, I have no idea. Again, I can't see the room, so I have no idea what equipment you have.

If 1 and 4 are both for lights, it makes sense that a singe switch controls them.

One other thing to check, is to make sure the terminals of those switches are rated to accept more than one conductor. There should be a label on the switch that tells you what type, and how many conductors can connect.


Without any of the information that I asked for in my comments. I'd say the 3 wire (black red white) most likely goes to one of the fans or the light box. The light box if both fans are fan only. Check the right hand switch and the make up in the light box especially if the light looks new . Someone may have replaced the light and left the red wire at the light box disconnected from the wires feeding the fan.

  • No such thing as 16 awg romex.
    – user24125
    Aug 7 '14 at 1:45
  • yea im sorry for that i was wrong, i was very confused. the red/ black/ white for the fan but still don't see a red wire on the fan, what do i do. can u explain which wire goes were. im really sorry if i am being a little diffcult. Aug 7 '14 at 1:58
  • From what I see the three wire that's the one that has the red wire goes to the light box (the junction box behind the light) the black wire that is connected to the switch with the red goes to the fan that is working you can verify this by removing it from the switch and see if it turns off the fan the fan that is not working probably has a 2 wire romex going to the box that the other end of the 3 wire is in since the black wire in the 3 wire feeds the light the red needs to connect to the wire going to the fan in this case white wires will connect to white wires.
    – user24125
    Aug 7 '14 at 4:16
  • You have 2 lights one of them should have the 3 wire to it.
    – user24125
    Aug 7 '14 at 4:24

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