Heat Shrink Installation Guide: Settings, Steps, Mistakes

Most heat shrink failures are made before the gun is switched on. Get the size and the sequence right and the joint outlives the cable. Get them wrong and you are redoing it in six months.

Tools and temperature

Use a heat gun rated 300-400 °C. Polyolefin starts recovering at about 120 °C and fully activates between 120-175 °C. A hair dryer (70-140 °C) will not reliably shrink it - do not try.

The one rule

Slide the tube onto the wire before you make the joint. Once the crimp or solder is done, the tube will not fit over it. This is the mistake every rookie makes once.

Step by step

1. Cut the tube to length, extending at least 25 mm past the joint each side.
2. Slide it well back from the work area.
3. Make the crimp or solder joint.
4. Centre the sleeve over the joint.
5. Heat from the centre outward in slow passes.
6. For dual-wall, wait for the adhesive bead at both ends - that confirms a full seal.
7. Let it cool before flexing.

Mistakes that cause failure

A lighter leaves soot and chars the surface (the carbon is conductive - a fault path on a live joint). Spot heating recovers unevenly. Wrong size - pick a supplied ID 20-30% larger than the largest object - lets the tube either not fit or not grip. Flexing while hot deforms the seal.

Frequently asked questions