Splicing a Power Cord
Power cords get damaged from all sorts of things; over-enthusiastic weed-whacking or hedge-trimming, forgetting that the car's battery warmer was still plugged in, even being chewed up by dogs and rodents! New cords aren't cheap as any hardware store patron knows. This task shows you how to make that cord almost as good as new for the cost of a little time and effort. It demonstrates repairing a 3-wire power cord but the same techniques apply to their smaller 2-wire power cord cousins.
To splice a power cord, you'll need the following tools: a sharp knife, wire cutters, wire strippers, and a soldering iron and solder. You'll also need a 3-wire power cord and heat shrink tubing — 1/4-inch diameter to fit the inner wires and a larger size 50% larger than the diameter of the cord.
This project should take less than an hour:
1. Trim the separated ends of the cord and remove any frayed, wet, or oxidized wire.
2. Cut a 6-inch piece of heat-shrink tubing with a diameter 50% greater than the cord's jacket.
3. Trim 4 inches of jacket from each piece of cord. Avoid nicking the inner wires or their insulation by scoring the jacket and flexing the cord until the jacket breaks away cleanly. Untwist and straighten each wire. Remove any string or filler material. Slide the heat shrink tubing over either piece of cord.
4. To separate the splices of each individual wire, perform the splice at a different point on each pair of wires. On the left-hand piece of cord, cut the wires as follows: hot — 2 inches from the jacket, neutral — 3 inches from the jacket, ground — do not cut.
On the right-hand piece of cord, cut the wires as follows:
• Hot: do not cut
• Neutral: 3 inches from jacket
• Ground: 2 inches from jacket
Strip each wire 1 inch. Each splice will be 1 inch apart, keeping plenty of insulation between the bare wires.
5. Cut three 1-1/2-inch pieces of 1⁄4-inch diameter heat shrink tubing. Slip one piece over each wire.
6. Starting with the neutral wire (it will be the easiest since both pieces are longer), cross the stripped wires at their midpoint and twist each around the other in opposite directions. This is a "Western Union" splice, originally invented for repairing telegraph lines in the mid-1800s! Continue twisting until the wires are snugly wrapped around each other.
7. Solder the wires together, center the heat-shrink tubing over the splice and shrink it.
8. Repeat Steps 6 and 7 for the hot and ground wires.
9. Center the large piece of heat-shrink tubing over the entire splice and shrink it.
10. Wrap the splice with good-quality electrical tape twice, once in each direction, overlapping each successive wrap at least 50%. At the end of the wrap, cut the tape and press it into place.
Do not pull the tape apart; that causes the top layer to begin to separate. Eventually pulled-apart tape comes completely loose (flagging).