How to Make an Extension Cord Using Solid House Wire
House wire was formerly generically referred to as "ROMEX®," after the Rome Wire Company which manufactured it until 2003. That company was taken over by Southwire, and today ROMEX® is a trademark name, like Kleenex. Because it is not very flexible, it is not generally used for extension cords, but it can be. Use the correct gauge wire for the load you plan to service with the cord. Common gauges, in order of increasing thickness, are 14, 12 and 10. For loads of 15 amps or more, use 12-gauge or thicker.
Cut off the length of wire you need from a roll and remove about 4 inches of sheathing from either end with a utility knife. Cut around the perimeter of the sheathing, being careful not to cut into the wires underneath, and pull it off with pliers.
Separate the wires underneath. Remove about 1/2 inch of plastic coating from the white and black wires with the splicing tool. Take the paper off of the bare wire.
Unscrew the screws holding the male connector together and separate it. Pass one end of the ROMEX® through the hole in the bottom piece and move it along the wire.
Connect the wires to the nuts inside the top part of the connector. Connect the black wire (hot) to the brass nut, the white wire (neutral) to the silver nut and the bare wire (ground) to the green nut. You may have to make a little bend in the ends of the wires to hook them around the nuts. Do this with pliers and bend the wire clockwise.
Slide the bottom up into place against the top of the connector. Verify that the sheathing extends into the hole of the connector. If it doesn't, disconnect the wires and trim them back a little.
Fasten the top and bottom of the connector with the screws provided and tighten them well. It is a good idea to wrap some electrical tape around the hole where the wire comes out. Repeat steps 2 through 6 with the female connector.
- The inflexibility of house wire makes it very inconvenient, especially if the cord is very long. If this becomes an issue, consider using regular extension wire instead.
- If you are using connectors that don't have a grounding pin, use two-wire ROMEX®. If you only have three-wire, just don't connect the ground wire. However, if you are using the wire to service an appliance with a three-prong plug, you must use three-prong connectors and three-wire ROMEX® and connect the ground wires.
- Never use extension cords in places where they can be damaged.
- Never use an extension cord as a permanent installation.
- Use plastic-coated exterior ROMEX® if you plan to use the extension cord outside.
Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.