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Thread: bathroom light/fan operate separately

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  1. #1

    Exclamation bathroom light/fan operate separately

    I am trying to have my bathroom light/fan operate separately, with one switch operating the light and the other operating the fan. The power coming to the switch is 3 wire (black, white, and ground). The wire coming from the light/fan is 4 wire (black, white, red, and ground). I have 2 single pole switches. How do I run the wires to the switches so that the light works from one switch and the fan works from the other?

    I draw a scheme of the situation i hope somebody can help me urgently. (i read on a website somebody had similar situation and answer was he hadn't have extra wire to able to do this.)

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  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    You may not be able to do it without running a new cable. You need to look in the fan assembly and draw what is there now.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Extreme DIY Homeowner Scuba_Dave's Avatar
    Join Date
    Jan 2009
    South of Boston, MA


    IF power comes to the switch

    Ground continues to each
    Neutral continues to each
    Incoming power goes to each switch
    (Next depends upon which color wire goes where)
    Other side of 1 switch is black wire to one device (fan)
    2nd side is red wire to light
    DIY Handyman (not 4 hire)
    I have enough to do to my own house

  4. #4
    Master Electrician Chrissimms's Avatar
    Join Date
    Oct 2008
    Cohutta GA


    The wire from the fan is a 3 wire (12-3) with a bare ground, 1st turn off breaker to the fan/light, 2nd remove the fan from the housing to check how the fan is wired up. Should be wired with the black (12-3) wire to the black wire from the fan, the red (12-3) wire to the blue or red wire (color depends on make of fan) both of the white wires from the fan should be wire nutted to the single white (12-3) wire.

    In the switch box.....
    According to the drawing
    Tie all whites together and wire nut
    tie all bare grounds together and put on the grounding screw of the switch
    Black wire (12-2) put on either black screw of the switch
    black (12-3) from fan/light put on bottom gold screw of switch
    Red (12-3) from fanlight put on top gold screw of switch.

    The 12-3 wire to the fan from the switch is the " switch leg"
    The 12-2 wire in the switch box is the input power.

    Reassemble fan and energize.

  5. #5
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default fan

    According to your drawing you only have one switched wire going to the fan. The black wire is either feeding from the fan to the switch and then on to the rest of the circuit, or power is coming to the switch from the right side and then the black wire is continuing on to the rest of the circuit while the red wire is operating the fan and light. As you said, you do not have enough wires to do the job you want to, unless your drawing is incorrect.

  6. #6


    Red on the left side of the double switch.

    Disconnect the two black wires connected to that one black wire.

    Connect each black wire to each connection on the right side of the double switch.

    So on left of double switch, red wire.

    On right side of double switch, one black wire to first switch, then the other black wire to the second switch.

    Then green to the ground connection on the double switch.

  7. #7


    I did what Chrissimms told and when i did that i see one button controlled light and fan and the other one receptacle on the wall. So i think light and fan connected above so it is an advanced job for me to do. Like most of you said it needs an extra wire.

    Thanks a lot all.

  8. #8


    IF your fan has a black and a red, then one powers the light and one powers the fan.
    You are thinking of a ceiling fan. His situation is a bit different. Blk is hot, red is switch leg to his bathroom light/exhaust fan.

    The existing wiring looks like either the fan or the light (whatever's wired to black) isn't switched at all
    The black wire is constant power.

    I fail to see how adding even a single wire in a house wired with Romex, would be a "fairly easy" job, for anyone, unless it has the attic above it for access.
    If it's an "old school" installation with a wall light above a medicine cabinet, the installation is pretty easy

    You are a plumber and you have been around for a while.....right?

    Picture this.

    Bathroom has a recessed med cabinet with a light on the wall right above it. If you are really lucky it is one of those 6" plumbing walls framed with offset 2x4's.

    His wiring description sounds like there is both the light switch leg and power in the light jbox. The fan sw leg would also come from the sw box.

    You pull out the med cabinet and take down the light fixture.

    You have power in the JB as well as the fan sw leg.

    You also have pretty good access to the wall cavity via the med cabinet niche. You just need to get from the light JB to a new switch location below it and install your ex fan switch/timer there.

    If it IS an offset 2x4 plumbing wall you can easily fish across the wall to locate the switch left or right.
    Last edited by 220/221; 05-06-2009 at 07:31 PM.

  9. #9


    Thanks for all ideas. Yesterday i checked fan box and decided to put a pull chain switch inside the box and that was easy i have no idea what is what behind the walls and i did not want to ruin the paint and wall.

  10. #10
    Homeowner Thatguy's Avatar
    Join Date
    Aug 2008


    Does X-10 home automation make modules for this? The receiver would need to be mounted inside the fan housing to decode the fan/light signals.


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