Wiring a Bathroom Exhaust Fan Light Combo It all depends on the specific bath exhaust fan and light combo unit you choose, so you must consult the installation manual and wiring directions. You may also see that the unit requires a dedicated circuit depending on the type of heating system the unit uses. Wiring a Light Switch – How to Wire a Bath Ceiling Fan Light Combo With 2 Switches Wiring a combination bathroom ceiling exhaust fan and light unit with the fan and light being controlled by separate wall switches is an easy project even for a beginner. The most challenging part Wiring Diagrams for a Ceiling Fan and Light Kit - Do-it Ceiling Fan with Light Kit Wiring Diagram. This wiring diagram illustrates the connections for a ceiling fan and light with two switches, a speed controller for the fan and a dimmer for the lights. The source is at the switches and the input of each is spliced to the black source wire with a wire nut.