Things You'll Need
3-prong electrical plug
Three wire extension cords have a heavy outer protective coating with three wires inside for positive, negative and grounding. Each internal wire has paper insulation around it and an additional protective coating. Extension cords may accidentally be cut with power tools, loose their protective coating or have breaks internally. Cutting out the defective section of an extension cord and rewiring the plugs on the ends creates a shorter usable cord.
Unplug the extension cord from the electrical outlet.
Cut the extension cord entirely through with wire cutters to remove the defective part of the cord or the defective plug.
Cut an one-inch shallow slit in the end of the extension cord with a utility knife to cut the outer protective coating only. Peel the coating back and pull the three wires out of it. Pull off the paper insulation around each of the three wires.
Strip about 1/2-inch of the white wire with wire strippers and twist the copper wires together. Repeat this process to strip and prepare the black and green wires.
Insert a slotted screwdriver into the new plug screws on the rear flat side of the plug. Turn each screw counterclockwise to loosen and remove them. Pull the back of the plug straight off. Insert the extension cord into the hole in the back of the plug.
Place the green wire around the green terminal screw on the plug. Tighten the screw clockwise. Attach the white wire to the silver terminal and the black wire to the gold terminal in the same manner.
Slide the plug back onto the wiring on the front while aligning the screw holes. Replace the screws in the plug back and tighten them clockwise.
Standard three-prong plugs attach to wiring by placing the stripped wire ends under a screw and tightening it. Heavy-duty plugs attach to wiring by inserting the wire in the hole next to a screw. When the screw is tightened on the side of the hole, it draws the wire into the hole as a worm gear.
Wire the opposite end of a three-wire extension cord in the same manner with a female plug.