Power Cord Splice and Repair

I'm sure some of you have come across this situation, a severed power cord, in my case one that was chewed through by some animal. Severed power cord

In this tutorial I'll show you how to repair it as good as new so you don't have to throw it in the trash.

Here are the materials I'm going to be using in the repair. Links to each item are provided:

The tools I'll use to help me perform the repair include:

  • Utility knife
  • Wire cutters
  • Wire stripper
  • Helping hands
  • Soldering iron
  • Hot air blower

    First step is to snip off the ends of the frayed cord so we have a nice clean starting point to make the repair.
    Snip frayed end of power cord

    We're going to remove a small piece of the outer jacket that house the wires inside. Use the wire strippers to measure how much you need to take off to make stripping the wires a lot easier later on.
    Measure length to strip off

    Using a utility knife score the outer jacket around its circumference. Be careful not to press too hard or you'll cut into the insulation of the wires underneath. This blade is really sharp so it takes almost no pressure to cut into the jacket. You'll be able to pull the jacket right off once its cleanly cut all the way around. Depending on the jacket you may have to cut along its length to remove it.
    Cut outer jacket of power cord

    Notice how the wires are twisted together, this helps them from producing kinks, we'll do the same at the end of the repair.
    Pull off outer jacket of power cord

    Check to see if you cut into the wire insulation. As you can see I did, but I'll be able to seal this up later so it won't be a problem.
    Examine cut wires

    Now that we have our wires free we can go ahead and strip the ends. I'm going to strip as little as possible while still ensuring I can get a good solder joint later on. A smaller solder joint will allow more flexibility in the cord around the area of the splice.
    Stripping wires

    Having a set of wire strippers like these makes this task not only easy, but quite enjoyable. Look how nice and even those ends are.
    Wires cleanly stripped

    Before we can start splicing the wires we need to prepare our heat shrink tubing. Select one that is the smallest diameter possible that will still slide easily along the cord. Don't forget to take into consideration whether the heat shrink will fit over the spliced section of wire.
    This looks like a nice fit, but if you're not sure just test out a small piece to see if it will shrink tight.
    Fit heat shrink tubing

    You want to make sure the length of the heat shrink tubing will not only cover the exposed wires but also that it overlaps the cord's jacket. Since I will be using this cord outside and want a watertight seal I'll be generous with the amount of overlap. You can easily estimate the overlap you'll get by lining up the cord and heat shrink like I'm doing here.
    Length of heat shrink tubing

    Once you're happy with the length of heat shrink tubing, slide it over one end of the cord and a few inches away from the end. We want it out of the way for now while we work on our splice.
    Slide on heat shrink tubing

    Now we're ready to join the two ends of the cord. Because we are dealing with 3 strands of wire at once it may be a little more difficult to work with than just one, mainly because the other 2 strands just get in the way. So we're going to focus on splicing just one wire at a time from start to finish.
    Separate wire strands

    I'm going to be using a mesh splice, it has a lower profile than other splice methods but it'll give the connection enough mechanical strength for this purpose.
    Bring the ends of the wire together so the individual strands intermesh evenly, then we twist the wire to give it some strength and a compact profile.
    Stranded wire mesh splice

    Using our helping hands we are ready to solder this first wire.
    Wire soldering with helping hands

    I'm going to use solder with a rosin flux core, this helps wick the solder through the individual strands to provide a solid electrical connection.
    Rosin flux core solder

    To ensure an even better solder joint I will dab a bit of solder flux paste, we want to maximize the amount of strand surface that is covered by the solder.
    Apply solder flux paste to wire splice

    Before I start soldering, I'm going to power up my solder fume extractor, always solder in a well ventilated area as the fumes are very toxic.
    Solder fume extractor

    Once the soldering iron is heated add some solder to the tip and clean it off, a clean tip will help conductivity of heat.
    Prepare soldering iron tip
    Clean soldering iron tip

    Put the iron tip under the wire connection and melt a little solder where the tip is touching the wire. This will help heat transfer faster to the wire strands.
    Heating wire for soldering

    As the wire heats up the solder will melt from the top and evenly disperse through the joint. You want to add enough solder to get a nice shiny surface that covers all the copper wire, but not too much that it pools up.
    Applying solder to copper wire

    Take a look and check if there are any loose copper strands, or protruding strands that need to be trimmed. I'm going to add a bit more solder to this joint.
    Soldered copper wire

    After the solder joint cools for a few seconds move on to the next wire and repeat the process. Bend the already soldered wires out of the way to make it easier to access the joint you are soldering. You can also see that extractor fan pulling the fumes away from me.
    Soldering fumes being extracted

    After all three wires are done you should have something like this, a clean and strong connection.
    Soldered power cord strands

    We are ready to apply the liquid tape to the solder joints. Place a cover to protect your work surface as it can get quite messy. Using the helping hands we'll secure the cable for this step.
    Soldered power cord with helping hands

    I'll let you read the directions on the back of the container. The main advantage over regular electrical tape is how it's able to seal the wiring from moisture.
    Liquid electrical tape directions

    We'll stir the sealant for about a minute and then apply a light coat onto the exposed joints with some overlapping the wire insulation.
    Applying liquid electrical tape

    I'll give you a good look to see how messy this could be. The liquid is very thin so make sure you scrape off any excess before trying to apply it anywhere. Again you want to overlap a bit of the wire insulation to make sure you have a good water seal to the copper underneath.
    Liquid electrical tape splatter

    Have a look around the wires to make sure you didn't miss any spots and dab any areas you need to. We'll wait 10 minutes and apply a second coat in the same manner.
    I'm also going to dab some along the cut lines when we removed the outer jacket. The instructions say wait at least 4 hours before using, I'll give it 10 to 12.
    Liquid electrical tape second coat

    Once the liquid tape is fully dried we can see there is strong seal around the wiring. One more step to make the final product look tidy and prevent kinks, give the cable a twist so the exposed wires are neatly wrapped together.
    Twist wire strands to prevent kinks

    Add one coat of liquid tape along the entire length of the unjacketed area. Once dried this will help the wires keep their form and add an extra layer of durability. I would give this 4 hours to dry before the next step.
    Final coat of liquid electrical tape

    Take the heat shrink tubing that was inserted earlier and slide it over the exposed section.
    Slide heat shrink tubing over spliced wires

    Make sure the tubing is centered by feeling for the end of the jacket underneath.
    Center heat shrink tubing over spliced wires

    Heat up your hot air blower and give a few passes of hot air until the tubing has fully shrunk. Start from one end and work your way slowly to the other side. This will ensure a tight fit as the heat shrink contracts uniformly.
    Begin heating shrink tubing
    Shrink tubing contracting 1 of 4
    Shrink tubing contracting 2 of 4
    Shrink tubing contracting 3 of 4
    Shrink tubing contracting 4 of 4

    Once you see the tubing is no longer contracting you're all done.
    Finished power cord repair

    And there you have it, a watertight splice that is also strong, durable, and flexible.
    Strong and flexible power cord splice

    Here is the full video of the repair...
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With 20+ years experience in programming and website development Simon has recently dipped his toes in electronics, and inspired by many great bloggers preceding him he created Simon Says Anything.