Cold Shrink Cable Accessories Installation: The Pull-core Method

Installing cold shrink cable accessories takes three steps: slide the pre-expanded sleeve over the prepared cable, position it accurately, then pull the spiral support core. The EPDM tube contracts radially and forms a tight seal around the insulation—all without heat, torches, or waiting. A complete termination finishes in about 30 minutes.

⚠️ Installation warning: Pull the support core straight along the cable axis. If the pulling angle exceeds 15° off-axis, the EPDM cold shrink tube may roll back unevenly, causing stress cone misalignment. Maintain a straight pull direction throughout the entire recovery process.

Installation sequence:

• Slide the cold shrink sleeve over the prepared cable end

• Position the stress cone at the insulation shield cutback

• Grasp the support core end and pull it counterclockwise

• Allow the EPDM tube to contract uniformly around the cable

Why Switch from Heat Shrink?

Heat shrink cable accessories require an open flame or hot air gun to activate. This creates multiple field problems:

• Open flames are prohibited in petroleum, chemical, mining, and tunnel environments

• Overheating degrades the material; underheating leaves the sleeve incompletely shrunk

• Each termination takes 1–2 hours with constant operator attention

• Thermal cycling gradually reduces elasticity, compromising the moisture seal over time

The cold shrink sleeve eliminates fire hazards and reduces installation time by 75%, making it the preferred choice for safety-sensitive sites.

How to Match the Correct Cold Shrink Tubing Sizes

Selecting the right cold shrink tubing sizes requires more than checking the conductor cross-section. The critical measurement is the outer diameter of the cable insulation shield layer—use a caliper, not a conversion table.

Sizing rule: The cold shrink tube's inner diameter must be 15–25% smaller than the cable's outer diameter to generate sufficient interfacial pressure for a permanent moisture barrier.

For 12/20 kV systems, cold shrink tubing sizes cover conductors from 35 mm² to 500 mm². For 18/20 kV applications, the range extends from 35 mm² to 630 mm². Single-core, two-core, three-core, four-core, and five-core configurations are available for low-voltage terminations and intermediate connections.

Environmental adjustment: For high-temperature or high-humidity installations, specify EPDM cold shrink tube with slightly higher durometer hardness. The EPDM compound offers excellent resistance to water, alkalis, acids, abrasion, and ozone, with a hydrophobic surface that maintains strong contamination resistance in polluted environments.

Step-by-Step Cold Shrink Sleeve Installation

1. Strip the cable layers according to the dimensions specified for the cold shrink sleeve being installed

2. Grind the semiconductive layer断口 into a smooth taper to prevent electrical stress concentration

3. Clean the exposed insulation surface thoroughly and apply the recommended silicone grease

4. Slide the cold shrink accessory over the cable end—verify the direction marking before positioning

5. Align the stress cone precisely at the insulation shield cutback point

6. Pull the support core straight and steadily until the EPDM cold shrink tube fully recovers

7. Install the ground braid and seal all termination ports

⚠️ Field fix: If the support core breaks during pulling, use needle-nose pliers to grip the remaining portion and continue rotating it out. The core will unwind completely with patience—do not cut the tube.

Factory Electrical Performance Verification

Every cold shrink cable accessory is electrically tested before shipment. Key pass criteria include:

✔ Power frequency withstand: 54 kV for 5 minutes, no breakdown
✔ Partial discharge: ≤10 pC at 20 kV
✔ Impulse voltage: 125 kV, 10 positive and 10 negative impulses, no breakdown
✔ Load cycling: 35 kV over 60 cycles at 95–100°C conductor temperature, no flashover

Additional validation covers thermal stability (23.4 kA for 2 seconds, twice, no visible damage), dynamic stability (82.6 kA for ≥10 ms), moisture exposure (15 kV for 300 hours indoors), and salt spray (15 kV for 1,000 hours outdoors).

Storage note: Pre-expanded EPDM cold shrink tubes should be stored at -10°C to 40°C, away from direct sunlight, to preserve rubber elasticity and shelf life.

Related Installation Checks

Termination quality depends on several interrelated factors: DC withstand testing after installation confirms the assembly integrity. Ground braid cross-section must match the fault current capacity of the cable system. Partial discharge monitoring during commissioning detects any stress cone mispositioning before the cable enters service.

Cold shrink technology replaces thermal activation with mechanical recovery—eliminating flame restrictions and heating inconsistencies that have plagued field installations for decades. Correct sizing and a straight pull axis are the two variables that determine whether a termination delivers 10+ years of reliable service.

12/20, 18/20 kV Fully Cold Shrink Three-Core Terminal – Installation Outline Drawing

Electrical Performance Tests

Product overview

◆The product is available in single-core, two-core, three-core, four-core, and five-core versions, and has been widely used for low-voltage cable terminations and intermediate connections.

◆Excellent surface hydrophobicity, ensuring the product maintains strong resistance to contamination.

◆Compact size, lightweight, and reliable performance.

◆Application Scope: The product demonstrates excellent cold and heat resistance, making it particularly suitable for high-altitude, cold, humid, salt-spray, and heavily polluted environments.

Installation requires no open flame, making it ideal for flammable and explosive areas such as petroleum, chemical, mining, and tunneling sites.

12/20 kV Single-Core Cold Shrink Indoor Termination – Installation Drawing	12/20 kV Three-Core Cold Shrink Outdoor Termination – Installation Drawing	12/20 kV Three-Core Cold Shrink Outdoor Termination – Supporting Drawing	12/20 kV Three-Core Cold Shrink Intermediate Connection – Supporting Drawing

Technical Data - Model Selection