I have a single switch and an outlet in a box in the bathroom. I am installing a bath fan and would like to operate the light and fan separately. I have a double switch. The trouble I am having is the switch only has one black, one white, and ground. The outlet has one black, one white and one ground. They are both hooked up separately. How do I incorporate another line one black, one white and one ground from the fan, Everywhere I read there should be one more black to have power coming in?

  • What circuit do you want the fan on? Can you get power from that circuit to the fan location, or do you want to power it from the circuit the outlet's on? – ThreePhaseEel Jan 15 '18 at 12:39
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    Are there any other wires at all in the junction boxes with the switch and outlet? – A. I. Breveleri Jan 15 '18 at 12:39
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    Electronic control module with special partner switch. Only thing I can think of. – Harper - Reinstate Monica Jan 15 '18 at 15:28
  • @Harper are you suggesting in your terse and cryptic comment, the installation of a remote controlled exhaust fan which would be powered by a cable (hot, neutral + gnd) from the light to the fan, but which would be switched by a wireless signal from a remote that would be affixed to the wall or sit in a little cradle on the wall? – Jim Stewart Jan 15 '18 at 19:11

What I get from your description of your bathroom circuit is you have both a wall receptacle and a light (presumably in the ceiling) with the light controlled by a wall switch in a single gang box. You want to add a vent fan and control it by a separate switch placed in a 2-gang box which would replace the existing single gang box.

In order to do this you will have to get both an "always hot" and a neutral to the exhaust fan and then have a "switch loop" to the new switch to control the fan. From your description of the wiring in the current box containing the light switch the white wire in this box is not a "neutral", but rather it is a "switched hot" going to the light. If this white wire is attached to one side of the switch, it is not a neutral.

There will be both a neutral and an always hot in both the box for the light and in the receptacle box. From one of these boxes you would connect a new cable to the new fan box to provide a neutral and a hot there. Then you would run another cable from the fan box to the new switch which would control the fan.

It might be easier to simply add another 1-gang box for the new switch for the fan rather than replace the existing 1-gang box with a 2-gang box, but I believe the usual way to do this is to have a 2-gang box.

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    Could use a single gang with a double switch. – Ed Beal Jan 15 '18 at 14:10
  • It takes some special equipment and skill, and I think two people, to run a new cable from an existing box inside a wall, up through the top plate and into the attic. but one person working alone can fish a new cable down from the attic through the top plate into an open hole in the wall. From there it is dead easy to insert the cable into an old work" box and then insert the box in the hole. – Jim Stewart Jan 15 '18 at 18:40

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