33kV Heat Shrink Cable Joints Connecting XLPE Cable In Underground Trench

Published 08 Jan 2018

• Application: Connecting XLPE-insulated high-voltage cables in an underground trench.
• Cable Joint Type: 33kV heat shrink cable joints.
• Cable Jointer: Garry Hardaker, Electrician and HV Jointer (Offshore).
• Article By: Chris Dodds, Thorne & Derrick. Estimated reading time: 5 minutes.

33kV Heat Shrink Cable Joints

Protecting High-Voltage Cables From Water Damage

33kV heat shrink cable joints connect and protect high-voltage power cables. These jointing kits include either mechanical connectors or compression crimp connectors.

They are suitable for polymeric-insulated cables, including XLPE and EPR cable types. Installers can also use them with armoured or unarmoured cables.

The joints support different cable screen constructions, including copper wire screens to BS7870 and copper tape screens to BS6622.

Heat shrink joints also feature integrated stress control sleeves. In addition, installers can use torque-controlled mechanical shearbolt connectors to join copper or aluminium conductors.

These connectors remove the need for traditional crimping tools and associated die sets.

Mechanical Connectors for Confined Spaces

Mechanical connectors offer a practical solution where cable jointers have limited working space. This includes underground trenches, manholes and cable vaults.

They are particularly useful when working with large cable conductors. In these situations, traditional hydraulic crimping equipment can be difficult to position and operate.

For example, Pfisterer SICON connectors use bolted connections. The cable jointer installs each connector directly onto the conductor using standard Allen keys.

As the installer tightens the bolt, it shears off at the specified torque. This creates the conductor connection without the need for hydraulic crimping equipment.

Pfisterer SICON – Cable lugs and connectors with stepless shearbolts for high-voltage cable joints and terminations.

How Heat Shrink Cable Joints Protect 33kV Cables

A heat shrink cable joint provides three important functions:

• Electrical insulation.
• Mechanical protection.
• Electrical stress control.

It must also help prevent water from entering the cable.

Although installers consider flooding during initial risk assessments, some projects require cables to operate in challenging environments. These conditions can include condensation, flooding and water exposure.

Therefore, cable joints need robust protection against moisture. This applies to both indoor and outdoor installations.

Heat Shrink Tubes and Water Ingress Protection

Heat shrink jointing kits include thick-wall tubes with an adhesive lining. These tubes provide a protective seal around the cable joint.

They also help protect against moisture and corrosion. Installers can use them on exposed cable installations and directly buried underground cables.

The outer black heat shrink tube forms a protective barrier. When the jointer applies heat, the inner adhesive lining melts and flows around the cable sheath. This helps seal the joint against water ingress.

Before installing the outer heat shrink tube, the jointer should clean, degrease and abrade the 33kV cable sheath. During installation, they should keep the flame moving to achieve an even recovery. This also helps prevent scorching or heat damage to the tube and cable.

Installing the Outer Heat Shrink Protection

The jointer applies heat evenly along the centre of the cable joint. As the tube recovers, it should form a smooth, wrinkle-free finish.

The heat-activated sealant should also appear at both ends of the tube, where it meets the cable sheath.

Once installed, the tough outer layer restores the cable’s sheath or jacket insulation. It also provides mechanical protection against underground trench backfill before the HV joint is energised.

33kV Heat Shrink Cable Joint Installation

Installers follow the manufacturer’s instructions when preparing and fitting 33kV cable joints.

These instructions provide the required cable preparation dimensions and marking measurements. They identify where to remove the outer sheath, semi-conductive screen and cable insulation.

The jointer then uses suitable cable jointing tools to prepare the cable and complete the installation.

Although these 33kV cable joints are not designed for permanent submersion, their heat shrink protection helps prevent water ingress. Installers can use them on underground cables and within cable containment systems in MV and HV substations.

33kV Cable Joint Selection and Technical Support

Choosing the correct cable joint is important for a reliable installation. The cable construction, operating voltage and installation environment all influence product selection.

If you need help selecting or specifying MV and HV cable joints or terminations, contact Thorne & Derrick for technical assistance.

Further Reading: High-Voltage Cable Accessories

For more information about cable accessories and installation considerations, explore these related articles:

• Dangers of Substandard Heat Shrink Cable Terminations on High-Voltage Systems
• HV Cable Terminations – A Report Into 11kV Heat Shrink Termination Failure

33kV Heat Shrink Cable Joint Installation Video

The following training video demonstrates how to install heat shrink joints on single-core 33kV cables.

It covers the main stages of cable preparation and joint installation. This includes the initial stripping and removal of the 33kV cable sheath, followed by the completion of the heat shrink joint.

The video was produced by SPS and includes a narrated installation guide. It is intended for familiarisation purposes only. It does not replace recognised industry training or the manufacturer’s competency requirements.

More 33kV Products for High-Voltage Cables

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33kV Cable Terminations

Thorne & Derrick – Specialist Electrical Distributor

LV ♦ MV ♦ HV

Thorne & Derrick distribute a comprehensive range of low-, medium- and high-voltage cable accessories. Our products support cable jointing, termination and installation projects across the UK and international markets.

We also supply cable pulling equipment for underground cable installations and electrical construction projects.

Our product ranges support work on underground cables, overhead lines, substation earthing and electricity transmission and distribution networks. Applications include LV, 11kV, 33kV and EHV systems.

Key Products

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• Electrical safety and arc flash protection.
• Cable glands and fusegear.

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Thorne & Derrick supply products from established manufacturers, including:

• 3M and ABB.
• Alroc, Band-It, Catu and Cembre.
• Centriforce, CMP and Elastimold.
• Ellis Patents, Emtelle, Furse and Lucy Zodion.
• Nexans Euromold and Pfisterer.
• Polypipe, Prysmian and Roxtec.

LV – Low Voltage Cable Joints, Glands, Cleats, Lugs & Accessories (1000 Volts)

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