Heat shrink tubing is a versatile component used in electrical and mechanical applications to provide insulation, protection, and sealing for wires and cables. When it comes to cable entry seals, heat shrink tubing plays a crucial role in ensuring a secure and waterproof seal around cable entry points. Here’s how it works:

1. Material and Properties

Heat shrink tubing is typically made from thermoplastic materials such as polyolefin. These materials have unique properties that allow them to shrink in diameter when heated, providing a tight fit around the objects they encase.

2. Application Process


  • Selection: Choose the appropriate size and type of heat shrink tubing for the specific cable and application. The tubing’s diameter should be slightly larger than the cable’s diameter before shrinking.
  • Cutting: Cut the tubing to the required length, ensuring it covers the entire cable entry point with some overlap.


  • Positioning: Slide the heat shrink tubing over the cable before making any connections, positioning it so that it will cover the entry point and the surrounding area once shrunk.
  • Heating: Use a heat gun or other heat source to apply even heat around the tubing. The temperature required varies depending on the material but is typically between 90°C to 200°C (194°F to 392°F).


  • As the heat shrink tubing is heated, it begins to shrink in diameter and tightly conforms to the shape of the cable and the entry point, forming a snug, secure fit.
  • The tubing’s length also reduces slightly during the process.

3. Sealing Mechanism

Adhesive Lined Heat Shrink:

  • Some heat shrink tubing comes with an inner adhesive lining (dual-wall heat shrink). As the tubing shrinks, the adhesive melts and flows, filling any gaps and forming a watertight seal around the cable and the entry point. This type of tubing provides enhanced protection against moisture, dust, and other environmental factors.

Non-Adhesive Heat Shrink:

  • For applications where moisture sealing is not critical, non-adhesive heat shrink tubing can be used. While it still provides a tight fit and good mechanical protection, it does not offer the same level of sealing as adhesive-lined tubing.

4. Benefits of Using Heat Shrink with Cable Entry Seals

  • Protection: Offers excellent electrical insulation, mechanical protection, and resistance to environmental factors like moisture, chemicals, and abrasion.
  • Durability: Enhances the longevity and reliability of cable connections and entry points.
  • Versatility: Available in various sizes, colors, and materials to suit different applications and requirements.
  • Ease of Use: Simple to apply with basic tools and provides a professional finish.

5. Applications

Heat shrink tubing is used in a wide range of industries and applications, including:

  • Electrical and Electronics: Insulating and protecting wiring connections, splices, and terminations.
  • Automotive: Protecting cables and wire harnesses from heat, moisture, and abrasion.
  • Marine: Sealing and protecting cables in harsh, wet environments.
  • Aerospace: Ensuring reliability and safety in high-stress and high-temperature environments.


Heat shrink tubing is a reliable and effective solution for cable entry seals, providing insulation, protection, and sealing properties that enhance the durability and performance of cable installations. By selecting the appropriate type and size of heat shrink tubing and applying it correctly, you can achieve a secure and professional finish for your cable entry point.

How Heat Shrink Works With Cable Entry Seals