Introduction: Power Cord Repair

Extension power cords are one of the most common household items needing repair. Dealing with electricity can be frightening. The proper precautions must be taken in order to avoid injuring someone. That being said anyone with the proper tools can correctly and safely repair a torn or cut power cord. This guide will discuss basic electrical safety I’ve learned through taking Robotics courses at LATI and working for Daktronics. In addition, it will be discussing the proper tools and materials needed for repair.


The tools required to repair this issue go as follows, a wire cutting tool, a sharp knife, a lighter, a tape measure and a soldering iron. The materials in conjunction with this process include solder and heat shrink.

Step 1: Safety Info

In terms of electrical safety, the main reason to repair a power cord is due to exposed wire. This means there is a cut deep enough into the cord to expose the copper underneath the insulation. Exposed copper carrying an electrical current could potentially turn into bad news. If the hot (normally black) wire were to come into contact with the neutral (normally white) wire it could cause a short. A short circuit will cause a fuse to blow and could potentially emit sparks.

Step 2: Damage Removal and Re-work Prep

The initial step in repair is to remove any remaining cord that shows damage in order to prolong the quality of the equipment. Despite removing the initial damage the next course of action will be to cut into the power cord again. Using the knife, make an incision into the jacket of the power cord starting one inch from the end. Take care in doing so, as to not accidentally cut into the insulation of the wire and create the problem all over again. At this time, open the jacket of the cord to reveal three different colored wires. Peel the cut jacket away from the wires and remove it with the wire cutting tool. As soon as the jacket is removed, strip back the insulation on all three wires at a quarter of an inch. Repeat this process with the opposite end of the power cord.

Step 3: Wire Tinning

Now that the prep work has been completed for the cord it’s time to begin the soldering steps of repair. “Tinning” is the term used when covering copper wire with solder. By the same token, tin each copper wire with the solder. Thereupon completing this step, put a two-inch piece of heat shrink over the jacket of the power cord. Move the heat shrink as far away from the re-work area as possible, it will be used at a later point in time. Furthermore, place a half-inch piece of heat shrink over the three single wires on the power cord. As shown above, keep these pieces of heat shrink out of the way.

Step 4: Soldering

At this point, the wire holding the heat shrink will be attached to the wire of the same color on the opposing side of the power cord using solder. Set both wires side by side and flush with each other. Add a small amount of solder and combine the two ends into one. In essence, the pair should take up the same width as the overall single wire. Provided that, do the same process for the remaining two colors of wire.

Step 5: Heat Shrink

Up to the present time, all of the necessary electrical connections have been made. The last steps are focused on protecting each of these individual connections. First, adjust the heat shrink on the newly combined wires so that the soldered areas are covered. Upon completion, place the flame from the lighter a few inches away from the heat shrink. The heat shrink should tighten to the wire in just a few seconds using a back and forth motion with the flame. Be cautious in how long the flame is heating, too long and the wire will melt. Finally, take the last piece of heat shrink and cover the exposed strands of wire. The heat shrink should be touching either end of the power cord’s jacket. Duplicate the previous process by heating with the lighter flame. After completing these steps, the power cord is safely repaired and ready for use.