What is Heat Shrink Tubing and How to Use It — A Practical Guide

Heat shrink tubing is a shrinkable tube made of polymeric material that, when heated, reduces its diameter and tightly encloses the wire or component beneath it. It is used for insulation, protection, and marking of wires and cables in electrical installations, electronics, and automotive technology.

How Heat Shrink Tubing Works

Heat shrink tubing is made from a special polymer with shape memory. At room temperature, the tube is in an expanded state and can be easily placed over the wire. When heated to 70–120°C (depending on the type), it shrinks uniformly and fits tightly. After cooling, it permanently retains its shrunk shape.

Shrink Ratio

The most important characteristic when choosing heat shrink tubing is the shrink ratio — it indicates how many times the diameter decreases upon heating:

- 2:1 — standard; shrinks to half its diameter. Suitable for most applications.
- 3:1 — shrinks to one-third. Used for uneven or tapered surfaces.
- 4:1 — maximum shrinkage. For special applications with a large difference in diameters.

For most household and electrical engineering applications, a 2:1 ratio is sufficient.

Types of Heat Shrink Tubing

Standard Heat Shrink Tubing (PE — polyethylene)
The most common type. Shrinkage temperature around 70–100°C. Suitable for wire insulation, marking, and protection against mechanical damage. Available in many colors.

Adhesive-lined Heat Shrink Tubing (with internal adhesive)
Contains an inner layer of hot-melt adhesive that fills irregularities when heated and provides waterproofing. Used for outdoor cable connections, marine, and automotive applications.

Teflon Heat Shrink Tubing (PTFE)
Withstands very high temperatures and chemically aggressive environments. Used in industry and laboratories.

How to Install Heat Shrink Tubing — Step by Step

Step 1 — Choose the correct size
The diameter of the heat shrink tubing in its expanded state should be 20–30% larger than the wire's diameter. If it's too tight, it won't fit; if it's too wide, it won't adhere properly.

Step 2 — Cut the required length
Cut a piece slightly longer than the area you want to cover — heat shrink tubing also shrinks lengthwise (about 5–10%).

Step 3 — Place it over the wire
Slide the heat shrink tubing over the wire before making the solder joint or connection (if necessary). After soldering or connecting — slide it to the desired position.

Step 4 — Heat evenly
Use a heat gun (recommended) or a lighter. Move the heating element evenly along the entire length of the heat shrink tubing. Do not concentrate heat in one spot — it may burn or shrink unevenly.

Step 5 — Allow to cool
Do not move the wire until the heat shrink tubing has completely cooled — about 1–2 minutes.

Applications of Heat Shrink Tubing

- Insulation of solder joints and splices
- Protection of cable ends and terminals
- Color marking of wires (phase, neutral, ground)
- Protection against mechanical friction and scratching
- Repair of damaged cable insulation
- Grouping of wire bundles
- Protection of cables when passing through sharp edges

Color Selection

According to IEC 60446, the colors of conductors in electrical installations are:
- Brown/black/gray — phase (L)
- Blue — neutral (N)
- Yellow-green — protective earth (PE)

When marking with heat shrink tubing, observe these colors to avoid confusion during future maintenance.

See available heat shrink tubing in our store:

Important: Electrical installations should be carried out by a qualified electrician. The information in this article is for educational purposes only.