Putting in a bathroom fan is important in homes to reduce excessive moisture that can damage paint and walls. The time to plan for a bathroom fan system is while the walls and ceilings are still open from remodeling or new construction.

Most bathroom fans have a light metal box that can be installed between the ceiling rafters or floor joists. The bathroom fan assembly will fit into this box as part of the final electrical work or appliance installation.

The attic or ceiling is the best place to run the exhaust vent. A dryer hose makes the best vent because of its low cost and flexibility. One end of the flexible hose attaches to the exhaust outlet in the metal box with a big hose clamp. The other end of the vent will go to an opening in the roof or the soffit.

There are different types of exhaust fans available for different needs. If its a simple bathroom fan, then you can use a single light switch to turn it on and off. If theres a light and heater with the fan, then youll need to use three different switches to control each component. There are some nice looking triple switches that work well for these types of fixtures.

Be sure to disconnect the electric breaker at the breaker box and make sure that other people in the home know what youre doing with the house electrical system to avoid electrical mishaps.

Lets say were wiring a fan and light combination. We can use 12-3 non-metallic sheathed cable which has three conductor wires and a ground wire. From the switch well need to have the house circuit wires to provide the power. Well run the 12-3 cable from the switch box to the fan. Therell be a red wire, a black wire, and a white wire, along with a copper ground wire in the cable sheathing.

Well use a double switch that fits into a normal switch box. The 12-3 electrical cable that runs from the exhaust fan to the switch can be wired first. You will need to wire the red wire to one of the hot screws on the switch. The black wire can be connected to the other hot screw. These will usually be on the same side of the switch over and under.

The switch will also have a screw that attaches to the house circuit power. The black wire that comes from the power circuit will connect to the switch giving it power. The white wire from the circuit power and the white wire from the fan can be joined together with a wire nut. You can also attach the copper ground wires together with a wire nut. Tuck all of the wires into the switch box and secure the switch in place.

Next, youll wire the light and fan with the 12-3 cable. There will be four wires with this fixture. The red wire from the fan will connect to the red wire from the 12-3 cable. There will be a black wire from the fan light. It will connect to the black wire from the power cable. The white wire can be combined with the other white wire and the ground copper wire can be combined with the cable ground wire with a wire nut.

Secure the fan in place with the attachment screws. Turn on the breaker to make sure that each component works when you flip the switch.