How to Wire a Duct Fan
- 1). Extend 14-2 with ground wire from the duct fan's location to the air-conditioning system's air handler. Cut the wire with wire cutters. A 14-2 with ground wire set consists of a bare 14-gauge copper wire and two 14-gauge wires with insulation. A protective plastic covering surrounds the wire set.
- 2). Push the tip of the knife into the middle of the plastic coating about 6 inches from the end of the 14-2 wire set and slice the covering to the end of the wire set. Pull on the covering and cut a 6-inch piece of plastic coating off of the wire set.
- 3). Remove 1/2 inch of the insulation from each wire with wire strippers. Place the insulated wire into the wire stripper's slot with the "14" label. Squeeze the stripper's handles and pull the insulation off of the wire. Repeat this for each insulated wire.
- 4). Remove the lid from the duct fan's electrical box with the correct screwdriver, often a 1/4-inch hex-head screwdriver. Some lids use a single screw located in the center of the lid and some lids use multiple screws located on the sides.
- 5). Insert an NM cable clamp into the hole on the side of the duct fans electrical box and tighten the locknut. Insert the wire through the clamp and tighten the two clamp screws.
- 6). Wrap the duct fan's black insulated wire around the 14-2's black insulated wire and hold them in place with a wire nut. Wrap the duct fan's white insulated wire around the 14-2's white insulated wire and hold them together with a wire nut. Wrap the duct fan's green wire around the 14-2's copper wire and hold them in place with a wire nut.
- 7). Replace the duct fan's lid and tighten the lid's screw with the correct screwdriver.
- 8). Turn the electricity that controls the air handler off. Most air handlers use a special disconnect switch, located within arm's reach of the unit, in addition to the circuit breaker. This switch allows a service technician work on the unit without the need to access the circuit breaker box.
- 9). Remove the screws that secure the air handler's lid to its housing with the correct screwdriver, often a 5/16- or 1/4-inch hex-head screwdriver. Pull the lid of off the housing. Verify there is no power present by touching the incoming wires with a non-contact voltage tester.
- 10
Push the wire that leads to the duct fan into the air handler's housing. Work the wire into the air handler's electrical box. If you have to run the wire through a knockout, use another NM cable clamp as described in step five. - 11
Follow the uninsulated wire that enters the air handler from the disconnect box. This wire ends at a terminal block. Several other wires also end at the terminal block. Loosen one of the terminal block's screws with a slotted screwdriver. Push the duct fan's white insulated and bare copper wire into the terminal block, then tighten the screw. - 12
Follow the blower motor's black wire into the air handler's electrical box to the fan relay, the electrical part the wire connects to. Connect the black wire from the duct fan to the same fan relay terminal to which the blower motor connects. With the duct fan's black wire connected to the fan relay and the white wire connected to the terminal block, the duct fan receives 120 volts when the fan relay turns the blower motor on. - 13
Replace the air handler's lid and turn the air handler on to test the duct fan.
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