Tag: Bathroom Fan Wiring Diagram

Dear Mr. Electrician:  How do I go about adding bathroom fan switch to my existing bathroom light switch to control my bathroom fan separately? Answer:  Depending on how the home was originally wired, adding bathroom fan switch could just be a matter of changing some connections at the existing light switch.  Then you could install a combination device with two single pole switches on one strap.  NOTE: Some text links below go to applicable products on Amazon.  As an Amazon Associate I earn from qualifying purchases. ADDING BATHROOM FAN SWITCH I have had this request a few times and in some cases all I needed to do was open up the existing wall switch and make some changes.  I would remove the wall plate, unscrew the screws holding the switch in the switch box, and pull the switch out away from the wall so I could access the wires.  Sometimes getting the paint off the wall plate screws is the most difficult part. If there is a cable inside of the electrical switch box that goes to the bathroom light fixture and another separate cable that goes to the bathroom fan then it is quite possible that a second switch could be added without installing additional wiring.  See the bathroom fan wiring diagram below. The original wiring would consist of a cable that brings the power to the switch box along with the two cables that go to the fan and the light separately.  Other cables could be present that supply power to other parts of the home.  They would just be connected to the hot and neutral. All of the white neutral wires would be spliced together using a wire nut or another type of wire connector.  The black wires that go to the fan and to the light would be spliced together with a black pigtail which would be connected to the single wall switch. The black wire from the power cable is connected to the other terminal on the switch.  When the switch is turned on power flows to both fan and light at the same time. Inside of the wall switch electrical box I would separate the black wire that goes to the bathroom fan from the black wire that goes to the light fixture.  Then a combination switch device such as the one below is installed to replace the old single pole switch. In the replacement scenario above, the existing hot wire in the switch box would connect to one of the black screw terminals.  Then the black wire for the fan goes under one of the brass screws.  The other black wire for the lighting goes under the other brass screw.  The grounding conductor only goes under the green screw. In the photo below you can see the wiring terminals.  Both screws on the left side are the hot connection which is obvious because of the break-off tab between them.  It is possible to have two separate circuits feeding this device just by breaking off that one little tab. ADDING WIRING FOR A NEW...