Wire A Double Switch For Bathroom Fan / Bath Fan & Light Dual Switch - Electrical - Contractor Talk . I have a vanity light on a single switch, a vent fan and ceiling light combo on a double switch and a gfci outlet that are wired together in that order. There are several other ways to wire this but i sa. You will have a black, red, and white wire, plus the ground. Connect the wire that's on the switch (not the one leading to the bundle), to the common terminal of the new double switch. Connect the black fan cable together with the black light wire and the black switch wire, and cover them. *** refer to more video separate switches for bath fan and light from single switch by sparky channel at this: Amazon prime student 6 month free trial (my affiliate link): Your single wall switch has now been converted to a double wall switch, so you can control lights independently or turn on a light without turning on a fan and vice versa. Single wall switch wiring | dua