How to Wire a Three-Pronged Plug to a Hard-Wired Appliance

A hard-wired appliance such a dishwasher or clothing dryer has a power cord that is spliced to integrate with the electrical wiring of the building instead of a power plug. The connection makes the device immovable. You could move such appliances if the wiring is connected to electric plugs. The same cord that connects to the house wiring may be connected to a power plug for 120-volt or 240-volt electrical outlets, depending on the power supply need of the device to make moving it possible.

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Three-prong switched plug

Step 1

Shut off the power to the appliance at the breaker panel. A hard-wired appliance is probably on a dedicated circuit with a labeled breaker switch. Turn off the main power switch at the top of the breakers to cut power if you cannot identify the correct breaker. Lock the breaker box or tape a warning note to it until the work is finished.

Step 2

Open the junction box containing the spliced connection to the house wiring. Remove the lower panel of a dishwasher to access its junction box. The junction box for a dryer or other appliance will be on a nearby wall. Open the box by swinging the door upward or to one side.

Step 3

Remove the wire nuts over the spliced connections on the black and white wires. You may slice the bare copper ground wire and cap it with a wire nut, or you may secure it to a screw terminal inside the box. Twist off the wire nut, or unscrew the terminal to remove the copper ground wire. Cut off the bare wire ends with wire cutters.

Step 4

Strip off 1/2 inch of the insulation from the black and white wires with wire cutters. Use 240-volt plugs for clothes dryers, and 120-volt plugs for dishwashers. Twist the bare wire ends from the black and white wires around the matching colored wires on the power plug cord. Cap the connections with wire nuts. Twist the bare copper wire around the green wire from the power plug and cap the connection with a wire nut.

Step 5

Wrap electrical tape around each wire nut connection the adjoining wires. Wrap another layer of electrical tape around all three wires and extend the wrapping in both directions to cover an inch the cable from the appliance and the cable for the plug.