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Solution

Medium Voltage Cable Jointing

Rebuilding insulation screen and sealing across a jointed conductor from 6 kV to 36 kV

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Medium Voltage Cable Jointing

The Problem

Why This Is Harder Than It Looks

A medium voltage joint has to do four things at once. It has to carry current through the connector, rebuild the insulation to the same thickness the cable had, restore the semiconductive screen and the metallic screen so the field stays where it belongs, and seal the whole assembly against water for the next thirty years. Get any one of them wrong and the joint fails.

Process

From Requirement to Delivered Product

Design material selection prototyping production quality control packing logistics and after sales

  1. 01

    Design

    We start from the cable construction on both sides. Conductor size insulation diameter screen type and jacket diameter decide every tube size in the build. Where the two cables differ the joint becomes a transition joint and the insulation build changes.

  2. 02

    Material Selection

    Stress control grade is set by voltage class. Insulation build is set by the required wall thickness. Screen restoration is either a co extruded layer in the same tube or a separate component depending on the design.

  3. 03

    Prototyping

    For a new joint design we build a sample against the drawing and measure the recovered geometry before any production tooling is committed.

  4. 04

    Production

    Compounding extrusion and radiation cross linking run in our own plant. Co extruded double and tri layer tubes are made in a single pass so no interface can trap air.

  5. 05

    Quality Control

    Tensile elongation heat aging dielectric strength volume resistivity and tracking resistance are tested in our own laboratory on every production lot.

  6. 06

    Packing

    Kits are packed to the agreed bill of materials with a pack list an illustrated instruction sheet and customer branding where required.

  7. 07

    Logistics

    Standard configurations ship in 5 to 10 working days. Export documentation and certificates travel with the shipment.

  8. 08

    After Sales

    Installation questions go straight to an engineer on WhatsApp. Field feedback changes the next batch rather than sitting in a complaints file.

Products

Products Used in This Solution

C15 Medium Voltage Heat Shrink Cable Accessory Kits 8.7/15 kV
C15

MV Kits 8.7/15 kV

Indoor outdoor and joint kits for 8.7/15 (17.5) kV single core and three core cable tested to IEC 60502-4

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C35 Medium Voltage Heat Shrink Cable Accessory Kits 26/35 kV
C35

MV Kits 26/35 kV

The highest voltage class in the range covering 26/35 (40.5) kV single core and three core cable to 630 mm²

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C105 Semi Conductive and Insulation Double Layer Heat Shrink Tube
C105

C105 Double Layer Tube

Co extruded heavy wall tube that restores insulation and the outer semiconductive screen in one operation up to 36 kV

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C106 Tri Layer Heat Shrink Tube for Medium Voltage Joints
C106

C106 Tri Layer Tube

Ultra heavy wall tube combining semiconductive screen plastic insulation and a fast recovering elastomeric inner layer

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C107 Plastic and Elastomeric Insulation Double Layer Heat Shrink Tube
C107

C107 Insulation Tube

Ultra heavy wall insulation for joints where the cable screen is restored separately from 6 kV to 36 kV

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C102-10 Stress Control Heat Shrink Tube up to 24 kV
C102-10

C102-10 Stress Control

High permittivity black tubing that redistributes the electrical field at the screen cut back on 6 to 24 kV cable

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C102-35 Stress Control Heat Shrink Tube up to 36 kV
C102-35

C102-35 Stress Control

The 36 kV stress control layer with a dielectric constant of 25 to 50 for 26/35 kV terminations and joints

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Y1 Heat Shrink Breakout Boots for Multi Core Cable
Y1

Y1 Breakout Boots

Molded two three four and five leg boots with adhesive on the big end and every leg for 1 kV to 36 kV cable

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Outcomes

What You Get

  • A joint that satisfies the full IEC 60502-4 joint test sequence including 30 heating cycles under one metre of water
  • Partial discharge held to 10 pC maximum at ambient and at operating temperature
  • Insulation rebuilt in one shrink operation rather than four separate layers
  • Screen continuity restored with braid and constant force springs supplied in the kit
  • No cure time so the joint is energisable as soon as it cools

FAQ

Medium Voltage Cable Jointing Frequently Asked Questions

What is the difference between a joint and a transition joint
A straight joint connects two identical cables. A transition joint connects cables of different construction such as paper insulated to XLPE where the insulation thickness and screen system differ. Transition joints are built from individual layers rather than a standard kit.
Can a joint be installed in a flooded chamber
The joint must be built in the dry. Once installed and cooled a correctly built heat shrink joint is tested for 30 heating cycles under one metre of water at 2.5 U0.
How is the metallic screen restored
Tinned copper braid held with constant force springs and sealed with mastic. All of it is supplied in the kit.
Which insulation tube do I need
C105 for a double layer build with screen restoration C106 for a 35 kV build needing 11 to 14 mm of wall and C107 where the screen is restored separately. Send us the cable data and we will confirm.
How long does a joint take to install
A trained jointer completes a 15 kV three core joint in a few hours including preparation. The heat shrink work itself is the fastest part.
Do you supply the connector
Connectors are optional because most utilities specify their own brand and barrel length. Tell us your preference when you enquire.

Still need an answer ask our engineers on WhatsApp

Other Solutions

Explore the Rest

Cable Termination Indoor and Outdoor

Field grading anti tracking insulation and creepage from 0.6/1 kV to 26/35 kV

Switchgear and Busbar Insulation

Raising internal clearance inside compact switchgear and covering the joints a tube cannot reach

Emergency Cable Repair

Restoring a damaged jacket in place without cutting the cable or disturbing the terminations

OEM and Private Label Kits

Kits packed to your bill of materials with your brand on the carton the instruction sheet and every bag

Custom Formulation and Tooling

Changing a wall thickness a shrink ratio a colour or a molded shape when the catalogue does not fit

Start a Conversation About Medium Voltage Cable Jointing

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