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How to Wire a NEMA L14-20 Pigtail

    • 1). Turn off the main circuit breaker inside the electrical panel. Check the lights and appliances inside your home to make sure that there is no more power flowing through the wires. Do not work on the wires unless you are absolutely certain that there is no more power.

    • 2). Strip off 3/4 inch of insulation from each wire inside the outlet box, using a wire stripper. A 220-volt circuit has four wires that run from the electrical panel to the outlet box: a black 110-volt wire, a red 110-volt wire, a white neutral wire and a green or bare grounding wire. There should be another set of similar-colored wires that run to the next outlet in case the outlet is in the middle of a circuit and supplies power to another outlet.

    • 3). Cut about 6 to 8 inches of electrical cable having the same amperage, voltage rating and color as the existing wires, using diagonal pliers. Cut away the outer covering of the cable to reveal the inner wires. Strip off 3/4 inch from the tip of each wire.

    • 4). Hold all similarly colored wires together and cut the wires so that they are even on the end. Except for the green or bare wires, twist the ends of similarly colored wires together (including the similarly colored pigtail wires) by three or four turns to splice them, using regular pliers. Insert each set of spliced wires into an appropriate size wire nut of the same color and twist the wire nut clockwise to secure the connection. Hold the wire nut and lightly pull on each wire to check for loose connections that can cause the wires to heat up and burn.

    • 5). Connect the pigtail wires to the NEMA L14-20 receptacle by wrapping the bare tips of the black wire (hot) and the red wire (hot) each to a separate brass colored terminal screw on each side of the receptacle. Wrap the white wire (neutral) around the silver terminal screw and attach the green or bare wire (ground) to the green terminal screw. Tighten each terminal screw to secure each connection, using a screwdriver.

    • 6). Strip off 3/4 inch of insulation from both ends of a six inch green wire. Hold one end of the six-inch green wire and wrap its tip around the outlet box grounding screw in case the outlet box is made of metal. Hold the other end of the wire side by side with the other similarly colored grounding wires and splice all wires together by twisting the wires with pliers. Cover the spliced grounding wires with a wire nut. If the outlet box is made of plastic, simply splice all the green or bare wires together and cover with a wire nut.

    • 7). Tuck all wires carefully into the outlet box. Fasten the NEMA L14-20 outlet onto the box, using screws supplied with the outlet. Cover the outlet with its faceplate. Turn on the main circuit breaker and plug a 220-volt appliance into the outlet to check the connection.

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