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How to Heat Shrink Wire

Heat-shrink tubing can be cut to size.
tubes image by Dusan Radivojevic from Fotolia.com

Things You'll Need:

  • Heat source, preferably a heat gun
  • Knife or scissors

Heat-shrink tubing is made of a material that shrinks in diameter when heated. It is a fast and easy way to insulate, protect and add strength to wiring without sacrificing flexibility. Available in a range of decorative colors, heat-shrink tubing is also handy for tidying up joins, labeling and organizing your wires and cables.

A variety of materials are used to make heat-shrink tubing, such as Teflon, Neoprene elastomers, Kynar, Viton and PVC. These materials vary in properties, such as shrink temperatures, flexibility and resistance to abrasion, cutting, chemicals or heat.

Select tubing of an appropriate diameter for your project. Heat-shrink tubing is commonly marked with a ratio of its current diameter to its final diameter after maximal shrinkage. For instance, a 2:1 ratio means the tubing will shrink to half its current diameter, and a 3:1 ratio means the final diameter will be one-third the original diameter.

Cut the tubing long enough to cover your joint.

If you are splicing wires, slip the tubing over the end of one wire before you splice your wires.

Move tubing over the joint.

Heat the tubing with the heat gun until it shrinks securely over the join.


Heat-shrink tubing that is a little too narrow can be stretched with needle-nose pliers or tweezers until it can be slipped over the joint, then shrunk down to size.

Other heat sources--such as candles, lighters, torches or light bulbs--may be used if held at a distance from the tubing and moved up and down the tubing. However, these methods have a greater risk of burning the tubing, and may yield less satisfactory results.


  • Use care when operating a heat gun or other heat source. Anything hot enough to shrink tubing will be hot enough to cause a serious burn to human skin. Tubing may char or burn, and electronics may overheat if you do not keep the heat source moving up and down the tubing. Overheating tubing may cause it to become brittle.
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