Power is supplied to a North American home by two hot wires, each carrying electricity at 120 volts, and a return wire. Most circuits in the home use only one of these hot wires, but some appliances, energy-intensive ones like dryers or stoves, need both of them. Together, they supply 240 volts. To wire a 240-volt receptacle, you need a four-strand conductor with two hot wires, colored red and black, a white neutral, or return wire, and a bare ground wire. The wire also needs to be thicker than for a 120-volt circuit.
Instructions
1. Turn off the power to the circuit by flipping off the two-gang breaker that controls it. The breaker you need to turn off should be labeled, but if you aren't sure if you turned off the right one, test the leads on the cable with a voltage tester. Place one of the terminals of the tester on the end of the red or black wire and the other on the white one. If the circuit is live, it will read 240 volts. If the breaker is off, it will read 0.
2. Pull the cables through the back of the electrical box in the wall and give yourself about 8 inches of slack. Cut off about 6 inches of sheathing with a utility knife, then expose 1/2 inch on the ends of the insulated conductors with a wire stripper. If the wire is too thick for your stripper, use a utility knife.
3. Slip a mud ring over the wires and attach it to the electrical box with the screws that came with the ring. The mud ring is an adapter with holes at the sides, top and bottom for attaching a 240-receptacle to a standard electrical box.
4. Loosen the terminal screws on a 240-receptacle with a screwdriver. Insert the ends of the red and black wires into the clamping holes behind the brass screws, then tighten the screws. It doesn't matter to which brass terminal you attach the red or black wire. Insert the white wire into the clamping hole behind the silver screw, and the bare wire behind the green screw.
5. Push the wires into the electrical box, then screw the receptacle onto the mud ring. You can attach it vertically or horizontally, whichever is easier. Plug in the appliance and turn the breaker on.
Tags: about inches, black wire, into clamping, return wire, stoves need, utility knife