Repair an Electric Cord
How to properly (and safely) repair electrical cords. It will be a shorter cord; but it will be safe as new.
Steps
- Shut off power. A cord suspected of being defective or damaged should not be handled while energized.
- Disconnect the cord from the outlet.
- Check cord end(s). If an extension cord, unplug the any cord connected to it. With the end in in your hand, notice if it feels warm. A warm end indicates a potential problem (more on this later). The end should have the "blades" or "prongs" checked for evidence of disfigurement, melted, darkened or burned insulating materials around blades. Extension cords should have the female end checked for these same conditions.
- Check the cord length. Visually inspect the entire length of the cord for damage - such as cuts, tears holes or burn marks in the jacket or insulation. Slip the cord through your hand to feel for inconsistencies that may not be easy to see - especially on the blind side of the cable. Mark the area(s) of suspected damage.
- Inspect the marked areas of the cord. Determine which could be a potential source of danger to those using the cord, etc. from those that appear to be only superficial.
- Determine if a polarized plug and cord is being used. Many appliances and older "2 wire" (ungrounded) extension cords employ polarized cords and caps. Polarized cord caps consists of different width blades that only allows the plug to be inserted one way into an outlet. The cord caps are connected to a (flat) two wire cord. These cords have a feature to identify one wire from the other. One wire will either have a ridge running the entire length of the cord, have printed information about the cord on it at evenly spaced intervals, have different colored conductors (gold / silver), or some other means. Check the old cord end to see if it had a polarized type cap. If it does, it will be important to replicate which wire was connected to the wide blade and which was connected to the narrow blade.
- Cut the cord. Once the identifier has been determined to be present, choose a location between the appliance and the damaged section (as close to the damaged section as possible) and cut the remaining cord and end off.
- Install a replacement cord end (or "cord cap"). Only use a replacement cord cap with the same number of blades as the original. Round cords are usually three wire grounding types and have different color insulated wires under the outer jacket. If presented with a (1) white or gray wire, (2) a green or green / yellow wire and (3) a colored wire (often red or black), the green / yellow wire will be connected to the long, ground blade; white / gray to the wide blade and the remaining colored wire to the narrow blade (or openings if replacing the opposite end of an extension cord). If a flat, two wire cable; make sure the wire with the identifier is terminated to the blade of the same relative width as the original to maintain polarity is intended by the manufacturer.
- Check your work. Make sure all the small strands of the wire are secured under their respective terminals. These strands should be twisted together and then wrapped clockwise around any terminal screw(s). Strands that are permitted to bridge different terminals will cause a short circuit and can result in an arc flash, blown fuse or circuit breaker or worse. If all strands are not fully under their respective terminals, it effectively reduces the size of the wire to carry the load - and will cause heat build up or a reduced voltage at the other end. Tighten all connections securely and assemble housing to complete. Be sure to install any insulating barriers supplied with the replacement cord cap.
- Do not over-tighten any strain relief connector on the cord cap around the cable. Doing so can crush the cable jacket / wire insulation and create a new hazard to anyone that comes in contact with it.
- Test. If at all possible, shut off power to the outlet to be used and plug in the repaired cord and cord cap. Turn power back on and test the device or cord without coming into contact with the area of the repair.
- Not working? It is possible that there is more than one source for the problem. Warm cord caps can indicate excessive build up of oxidation, dirt, or other condition that is interfering with a good connection. The problem may lay inside the outlet (or the openings of an extension cord) as heat felt on one end of the cord will be present on the mating surfaces of the connection. Over time, the heating and cooling of the metal contact parts in the outlet become fatigued, resulting in less "squeeze" strength. These surfaces may no longer grip the blades of the cord cap sufficiently and may require replacing the outlet (or in the case of an extension cord - female end cord cap).
Tips
- When a cord is damaged, cut out the damaged portion and install cord caps as needed on each end. This will permit them to be plugged into each other so that they may be able to serve nearly full length again.
- Test extension cords by connecting a continuity tester or ohmmeter probes to the ground blade and opening; wide blade and wide opening and finally the narrow blade and opening. There should be an indication of continuity or 0 ohms each time. Next, test between each blade to the next. There should be no continuity or infinite ohms each time.
Warnings
- If presented wire colors that are different from steps above, you must determine which color wire connects to which blade. This can be done with an inexpensive continuity tool or tester or with an ohmmeter. Do NOT guess.
- The only safe way to repair any cord is to shorten it so that the defective portion is removed.
- Never splice a cord.
- Never tape over a broken jacket or insulated wires of a device / appliance cord or extension cord.
- Never install a 3 prong cord cap if 2 wires supply it, or install a 2 wire cord cap if 3 wires supply it.
