How to Re-wire a Potted Motor, Part 5: Covering Wire Joints with Heat Shrink Tubing

Now that we’re able to solder two wires together, we’ll use heat shrink tubing to cover the soldered joints. It’s quick and easy.

Heat shrink tubing is just a little tube of thin, rubber-like material. You cut it to length with scissors. Then you slide it over your wire joint, apply heat with a cigarette lighter or heat gun and it shrinks a predetermined amount, acting as insulation and protection. It comes in different sizes and many different materials, but there's a particular kind we need.

It’s easy to apply--if you get the right kind. Because I did not know this at first, after trying and failing to apply different types using a lighter, I wasted my money on a heat gun. Some types of heat shrink tubing only shrink at extremely high heat (heat gun), while others shrink at low heat (cigarette lighter). Get the right stuff and you can do this job with a $1 cigarette lighter. Get the wrong stuff and you waste $37.69 on a heat gun.

You’ll need two types:

- 1/8” Polyolefin Heat Shrink Tubing with a 2:1 Shrink Ratio
- 3/16” Polyolefin Heat Shrink Tubing with a 2:1 Shrink Ratio

I bought eight different kinds before I figured this out, and I hope to save you the trouble. You should be able to find the stuff at a hardware, electrical supply or auto parts store. If not, here’s links:





How to apply heat-shrink tubing

Take some of the wires that you’ve soldered together in your testing, cut off a 1” piece of HS tubing, and slide it down so it covers the joint, with some room left over on the sides. Have it clamped in the Helping Hands. Then, quickly run a lighter under it, using the blue part of the flame:



Easy peasy. The tricky part is that during actual application, we must remember to slide the heat shrink tubing onto a piece of wire, and slide it out of the way, before we solder it. Otherwise it may be impossible to get it on, as you'll see later.

Go on to Part 6: The Underwriter's Knot