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How to Wire a 2-Speed Whole-House Fan

Robert Sylvus

A 2-speed whole-house fan sucks warm air from the home's interior and dumps it into the attic, where the air exits the house through attic vents. Removing air from the interior creates a pressure differential which pulls cool air into the house.

The 2-speed whole-house fan's louvers only open while the fan runs, and prevents warm attic air from reentering the interior when the fan turns off. The switch on a 2-speed whole-house fan wires into a common 120-volt residential electrical circuit.

  1. Turn off the 2-speed whole-house fan's circuit breaker. This circuit breaker should control all electrical circuits in the attic.

  2. Remove the screws holding the fan switch's electrical-connection box's cover in place with the correct screwdriver, often a 1/4-inch hex-head screwdriver. Remove the lid.

  3. Look at and understand the whole-house fan's electrical connections. The box contains two leads -- short wires -- for the power supply to connect to. One lead runs to the whole-house fan's switch, and the other lead travels to the fan motor's neutral connection. Usually the switch's lead has black insulation, and the neutral lead has white insulation. The screw with green paint, which connects to the electrical box, acts as a ground connection.

  4. Push the wire set feeding electricity to the 2-speed whole-house fan into the electrical box. The box usually has a round hole with grommets for wire access. If the hole does not have a grommet, then install a wire clamp in the hole and push the wire through the wire clamp.

  5. Strip 1/2 inch of insulation from each insulated wire in the 2-speed whole-house fan's electrical box with wire strippers. Four wires have insulation.

  6. Encircle the wire set's ground wire around the 2-speed whole-house fan's ground screw. Tighten the ground screw with the screwdriver.

  7. Wrap the end of the 2-speed whole-house fan switch's lead around the end of the wire set's black wire. Tie these wires together with a wire nut.

  8. Wrap the end of the wire leading to the 2-speed whole-house fan's neutral wire around the end of the wire set's white wire. Tie these wires together with a wire nut.

  9. Replace the fan switch's electrical-connection box's lid and screw. Turn the circuit breaker on and test the fan.