Bath fans, also known as bathroom exhaust or ceiling fans, help draw moisture out of bathrooms. Fans helps prevent the build-up of mould and keep your mirrors clear of moisture. Bath fans are usually wired to an existing wall switch that controls an overhead light and a fan that you'll be replacing. The wiring of a bath fan is a fairly simple procedure, but it's important to follow a few safety steps along the way.
Turn off all power to the circuit you'll be working on at the home's circuit breaker box. As an extra fail-safe measure, tape a note to the box indicating that it should not be touched while you are working on the circuit.
Use a wrench to remove the old light or fan from the bathroom ceiling by undoing the nuts at the centre or side. Lower it out of the ceiling. As you lower the old light or fan, disconnect the wiring. In most cases the wires from the wall switch to the light/fan will be connected with wire nuts. Simply twist these to the left and pull off to disconnect the wires.
Wrap the wires from your new fan around the existing wires. Match the colour coding of the wires. In most cases there will be a black wire and a white wire, which you can match to the existing wires. Wrap the bare ends of the fan's wires around the existing wires, then slide a wire nut over the wires. Twist the wire nut to the right to firmly connect the wires.
Turn power back on to the circuit when the wires are connected and test the bathroom fan by turning on the wall switch. Turn the power back off and complete the physical installation of the fan.
Some fans or wiring circuits will have a third wire. This is a ground wire and should be connected to the corresponding wire on the fan. If the fan doesn't have a ground wire, simply tape this wire off with electrical tape.
Never work on a live electrical circuit. Always turn the power off at the source for safety and inform other members of the household what you are doing.