3M Cable Joints & Terminations

What We Learned from 3M Cable Accessories Training | Thorne & Derrick

Thorne & Derrick Team Takes Part in 3M Cable Jointing Training

Continuous learning and hands-on experience are essential in the electrical industry especially when working with critical infrastructure across LV and MV systems.

Recently, the Thorne & Derrick team took part in an in-depth 3M cable jointing training session, focusing on improving technical knowledge, product understanding and real-world application.

The session brought together team members from across the business, combining theory with practical demonstrations to strengthen confidence in specifying and supporting cable jointing and termination solutions.

3M cable jointing training with the Thorne & Derrick Team

The training session provided an excellent opportunity for the team to step away from day-to-day roles and engage directly with the products and techniques used in the field.

From working with jointing materials to observing installation methods, the day focused on building a deeper understanding of how solutions perform in real-world environments.

Covering everything from tapes and Scotchcast resins to LV & MV Joints and Terminations, the session offered both technical insight and practical experience—bridging the gap between product knowledge and real-world application.

Understanding Cable Jointing in LV & MV Systems

Cable joints and terminations are critical points within any electrical network. Whether connecting sections of cable or safely terminating them at equipment, these components must maintain electrical integrity under demanding conditions.

During the training, key focus areas included:

• Preparation of cables prior to jointing and termination using correct cable jointing tools
• Selection of appropriate materials for insulation and sealing
• Installation techniques for both LV and MV systems
• Common installation errors by HV Jointers and how to avoid them

For those specifying or supplying equipment, understanding these processes is essential when recommending solutions such as LV cable joints and MV cable joints.

The Role of Tapes & Resins in Cable Jointing

A significant portion of the session explored the use of electrical tapes and resins, which play a vital role in insulation, protection and environmental sealing.

• Insulating tapes are used to rebuild insulation layers and provide dielectric strength
• Sealing tapes help prevent moisture ingress and contamination
• Resin systems provide robust encapsulation for joints, particularly in harsh environments

These materials are commonly used alongside cable jointing systems to enhance performance and durability. For example, Scotchcast resin-based solutions are widely applied in underground or submerged installations where environmental protection is critical.

Heat Shrink vs Cold Shrink: What’s the Difference?

One of the most valuable parts of the training was understanding the difference between heat shrink and cold shrink technologies—two of the most widely used methods for cable jointing and termination.

Heat Shrink Technology

Heat shrink products are installed using controlled heat (typically via a gas torch), causing the material to shrink tightly around the cable.

• Provides a strong, durable seal
• Excellent mechanical protection
• Widely used across LV and MV applications

However, installation requires trained personnel and careful handling of heat sources, particularly in sensitive environments.

Cold Shrink Technology

Cold shrink products are pre-expanded and mounted onto a removable core. Once positioned, the core is removed and the material contracts automatically.

• No heat required – safer for hazardous or confined environments
• Faster installation time
• Consistent application with reduced risk of error

This makes cold shrink ideal for applications where speed, safety and repeatability are critical.

Terminations: Ensuring Safe Connections at End Points

While joints connect cables together, terminations are responsible for safely connecting cables to equipment such as switchgear, transformers and panels.

The training demonstrated how proper termination:

• Prevents electrical stress at the cable end
• Maintains insulation integrity
• Reduces the risk of partial discharge and failure

Both heat shrink and cold shrink technologies are widely used in cable termination systems, depending on the application and installation environment.

Why Product Training is Essential in the Electrical Industry

With increasing demand for reliable power across industries, the margin for error in cable installation continues to shrink. Training plays a key role in ensuring:

• Correct product selection for the Jointing, Termination & Abandonment
• Safe installation practices
• Compliance with industry standards
• Improved long-term performance of electrical systems

Key Takeaways from 3M Cable Jointing Training

• Understanding the difference between heat shrink and cold shrink is critical for correct product selection
• Tapes and resins play a vital supporting role in insulation and protection
• Proper jointing and termination directly impact system reliability and safety
• Hands-on experience significantly improves technical understanding
• Training ensures confidence when specifying and supplying electrical solutions

3M Electrical Cable Accessories | Low & High Voltage

Manufactured by 3M Electrical their range of Cold Shrink cable accessories including Joints & Terminations are used to repair damaged cables, replace cable fault sections, extend existing cable circuits and connect cable ends for termination onto electrical equipment bushings in switchgear and transformers, including LV 11kV, 33kV and 66kV power cables operating at medium/high voltages (MV HV).

3M Electrical solutions include Cold Shrink and Scotchcast Resin cable joints – 3M products provide permanent, durable and watertight cable seals, joints and terminations with excellent electrical insulation and unrivalled performance for low (LV), medium (MV) and high (HV) voltage cables and power systems.

Cable Sealing with 3M Scotchcast Resin

Cable Sealing with 3M Scotchcast Resin

3M Electrical Liquid Resin 2123 

3M Scotchcast Resin 2123 is a two-part, unfilled polybutadiene resin designed for temperature curing – the resin from 3M Electrical offers the following features, consistent across the full range of 3M Scotchcast Electrical Liquid Resins: this re-enterable resin is ideal for low voltage cable sealing and insulation in electrical boxes. It comes with the Easy Dispenser 250, ensuring a cleaner application with reduced waste.

The 2123 Resin is formulated for virtually every electrical application requiring a soft, re-enterable resin with good handling and performance characteristics up to 1000 Volts.

Contact us for 3M Electrical technical support, specification guidance or assistance on the selection of electrical insulating resins for all LV MV HV applications.

3M 2123

Scotchcast Electrical Liquid Resins

Typical Property Data – Room Cures

• Polymer Cure/Cured Form/ Filler/Colour – Polybutadiene Room-Temperature Soft, re-enterable Unfilled Translucent Amber
• Temperature Class – 0
• 3M Electrical Liquid Resin Product Number – 2123
• Mixing Ratio – Wt 1:1 Vol (%) 48:52
• Viscosity at 23°C (73°F) (Centipoise) – A = 350-750* B = 700-1400*
• Cure Schedules (Temp/Time) – 21°C (70°F) 24 hrs.
• Gel Time – 62 min

3M Scotchcast Re-Enterable Electrical Insulating Resin 2123 is a soft, two-part polybutadiene resin designed for cable splice protection. It offers excellent handling and performance features and is formulated to be re-enterable for splice sealing. This versatile resin bonds effectively to most cable jackets while providing moisture sealing.

The resin is characterised by good wetting properties and low viscosity, ensuring ease of application. It cures at room temperature and functions as an insulating material for cable splices up to 1 kV. Its flexible, soft nature allows it to flow smoothly, even at low temperatures, filling enclosures and reducing voids. It is tested in accordance with CENELEC HD 623.S1 (EN50393) standards and complies with 2011/65/EU (RoHS) and 1907/2007/EC (REACH) regulations.

3M Scotchcast Resin Features

• Re-accessibility of the cable connection
• Homogeneous and reliable insulation
• Good adhesion of the resin on cables and on itself
• Excellent protection against water
• Low exothermic reaction temperature (0,6 K raise from 24° C)
• Continuous operating temperature of the resin at 90° C, emergencies up to 130° C

3M DISTRIBUTORS, STOCKISTS & SUPPLIERS

Thorne & Derrick provide competitive prices and fast delivery from stock for the complete range of 3M Scotchcast and Cold Shrink cable joints, terminations, resins and Scotch electrical tapes – we stock high voltage cable joints and terminations manufactured from 3M using Cold Shrink for 11kV and 33kV cables.

3M Terminations | Surface Tracking on Medium Voltage Cable Terminations

Surface Tracking – 3M Medium Voltage Cable Terminations

Surface Tracking on Cable Terminations

Surface tracking is the irreversible damage and degradation on the surface of a medium or high voltage cable accessory or  insulative material, such as a cable termination, due to the formation of conductive, carbonized paths.

Tracking results when discharges cause carbon to be left on an insulating surface as a result of the degradation caused by the heat of the discharge. This carbon deposit will grow to eventually create a continuous conducting path, which will lead to catastrophic failure.

Cold Shrink & Condensation In Medium Voltage Switchgear & Cable Terminations

Hydrophobic silicone Cold Shrink terminations provide excellent performance in Medium Voltage electrical equipment, such as switchgear, where cables endure temperature fluctuations caused by thermal cycling when under load – this “heating and cooling” effect condensates potentially causing premature partial discharge at the cable termination point. 3M Cold Shrink technology has a material tendency to reject and repel moisture accumulation and thereby reducing the probability for discharge-initiated erosion and tracking on medium/high voltage cable terminations.

N2XS(F)2Y Cable Terminations 12/20 22kV 24kV

Energising Data Centres | The QTIII range of MV Terminations are approved and in widespread service throughout the data centre sector for 12/20 (24)kV connection of N2XS(F)2Y Medium Voltage Cables with XLPE Insulation, Copper Wire Screen and Stranded Copper Conductor to BS EN 60228 into electrical switchgear equipment.

Surface Tracking Causes

Carbonized paths can occur from the dielectric breakdown of insulation, and/or by the introduction of contaminants on the surface that allow for electrical discharges across the surface.

The 3 factors that enable surface tracking to occur on cable terminations (MV HV): 

Hydrophobicity

3M Terminations | Protecting Against Tracking

Tracking is defined as a process that produces localised irreversible deterioration on the surface of an insulator, resulting in the loss of the insulating function by the formation of a conductive path on the surface of the insulator.

Silicone is an excellent track resistant material and is hydrophobic, repelling water and making the insulator self-cleaning which results in a dryer surface and lower leakage currents. 3M outdoor cable terminations include 3M rain sheds which disrupt any wet leakage paths that occur in industrial environments and also allows the creepage distance of the termination to be much shorter.

Insulator Skirts

Use of skirts on cable terminations increases the creepage distance (leakage distance) between the voltage source and ground plane. The undercut skirts disrupt wet leakage paths that occur in outdoor environments.

Advanced Materials

Insulators and skirted assemblies are made of formulated silicone rubber, which has excellent tracking resistance and hydrophobic properties. Special High K materials formulated to effectively control electrical stress.

Effective Stress Control

Electric field stresses are distributed in a controlled manner along the entire termination length. Voltage stress concentrations on the insulator surface are kept below 15 V/mil at rated voltage.

Further Reading

• 66kV Terminations | NEW Stock Introduction for 3M Cold Shrink Cable Terminations
• Stress Control | MV Cable Terminations by 3M Electrical
• Cable Jacket Repair | 3M Electrical Webinar

3M DISTRIBUTORS, STOCKISTS & SUPPLIERS

Thorne & Derrick provide competitive prices and fast delivery from stock for the complete range of 3M Scotchcast and Cold Shrink cable joints, terminations, resins and Scotch electrical tapes – we stock high voltage cable joints and terminations manufactured from 3M using Cold Shrink for 11kV and 33kV cables.

LV, MV & HV Jointing, Earthing, Substation & Electrical Eqpt

Thorne & Derrick International are specialist distributors of LV, MV & HV Cable Installation, Jointing, Duct Sealing, Substation & Electrical Equipment – servicing UK and global businesses involved in cable installations, cable jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.

THORNE & DERRICK Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV HV 

Thorne & Derrick Certificated by 3M for Medium Voltage Training & Product Familiarisation

Thorne & Derrick have successfully hosted the 3M Electrical “Train the Trainer” Programme and are now the first Certificated UK Distributor for this innovative scheme introduced to support MV Cold Shrink Cable Accessory installation competency.

T-t-T has been conceived by 3M to empower their Approved UK Distributors to deliver Product Training and Demonstrations to customers and ensure the highest levels of installation quality and safety are achieved – reducing cable failures, increasing reliability and securing both the revenue and reputation of asset managers and owners.

We had the privilege of welcoming industry expert Allan Russell (Application Engineering Specialist at 3M United Kingdom) who provided excellent tuition and guidance to our team of Technical Sales Engineers on the installation process of 11/33/66kV Cold Shrink Joints and Terminations.

The focus for the 2 days intensive session was the advancement of education, skills and technical knowledge for our Sales Team to best support the Medium Voltage Cable Accessory requirements of all industries – we covered all practical aspects of Cable Preparation & Accessory Installation for the 3M Cold Shrink ranges of Joints & Terminations covering voltage classes 11kV, 33kV and 66kV.

“The Train-the-Trainer concept enables Thorne & Derrick, as a Specialist Distributor for 3M Electrical since 1985, to bolster our customer service and field support to clients and is the perfect complement to our recent appointment as Approved 3M Electrical Kitting Partners – this is a further formidable personal achievement for Jonny Hewitt and another business accolade for Thorne & Derrick,” comments Chris Dodds (Sales & Marketing Manager – Thorne & Derrick).

Rail Electrification Innovation | The next-generation of 25/45/52kV Network Rail PADS ColdShrink Joints with Concentric Neutral, stocking at Thorne & Derrick.

Further Reading

• Thorne & Derrick Electrifying Industry With 3M
• Thorne & Derrick Appointed 3M Electrical Kitting Partners

Thorne & Derrick are Specialist Distributors to EPC’s & Contractors working on the design, construction and maintenance of UK, European and international projects supplying an extensive range of LV HV Cables, Accessories Jointing, Substation & Electrical Eqpt – this includes Hazardous Area (ATEX & IECEx Certified) Equipment to provide Power, Heating & Lighting to the Potentially Explosive Atmospheres industries.

Based in the UK, we are highly customer responsive and absolutely committed to providing a world-class service.

Since 1985, we have provided expert technical support and express delivery from extensive UK stocks to world-wide destinations.

Renewable Energy Energisations at Medium Voltage with 3M Electrical

MV Power

Reliable Solutions for Renewable Electrical System Installations

Since 1985, Thorne & Derrick have been Authorised Distributors for the 3M Electrical range of Low, Medium & High Voltage Cable Accessories for the insulation, connection, repair and provision of reliable electrical power up to 66kV utilising Cold Shrink, heat shrink, Scotch Tape and Scotchcast Resin technologies.

For more than 30 years, 3M Electrical has been committed to delivering comprehensive solutions tailored to the needs of challenging renewable energy projects, including wind farms, solar farms, and battery energy storage systems.

3M understands the pivotal role that well-designed and dependable electrical installations play in maximising the benefits of renewable energy sources. As energy demands increase and circuits operate at high capacities, minimising downtime becomes essential for maintaining efficiency and productivity.

To address these challenges, 3M offers a comprehensive range of easy-to-install and reliable electrical solutions across Low, Medium, and High Voltage applications. Their products are designed to withstand the rigours of modern energy systems while ensuring optimal performance.

Together, we can collaborate with you to provide strong technical support, training and customised product kits to help you keep your system running.

Power Cable Accessories

Easy-to-install, reliable solutions

3M™ Cold Shrink Medium Voltage splice kit QS200 12-36 kV	Designed from the ground up, these medium voltage cable splices are one of the pinnacles of 3M’s performance, quality and reliability these kits are used with 1-core and 3-core cables, armoured or non armoured. No special cable jointing tools, torches or other heat sources needed.
Designed using a unique Cold Shrink delivery system. Products are supplied pre-stretched on a removable core for efficiency and ease of installation. Electrical field control device pre-installed in the insulation body help to avoid complexity during the installation. The specific properties of the insulating silicon body allow to terminate wide range of cable cross sections. 3M™ MV termination kits are available both with and without mechanical lugs included. 3M™ QT-III Termination is a further development of the QT-II. It has similar functionality but offers additional advantages for the end user. The main advantages of the QT-III Termination are that it contain fewer individual components. This eliminates time-consuming installation steps, which leads to fewer chances of error.	3M™ Cold Shrink Medium Voltage Termination QT-II3M™ Cold Shrink QT-III Termination Kit 12-36 kV
3M™ Separable Connector Kit 12-36 kV	The Separable Connector is used to establish the connection between the cable and switchgear, transformer or other equipment. Products are moulded using high quality EPDM and sold in packs of 3 phases and they come with stress control element, earthing set, mechanical cable lug and assembly instructions. The straight, elbow and T-plug connectors cover a wide range of cable cross sections. All kits are fully type tested to Cenelec HD 629.1 (DIN VDE 0278).
3M™ Cold Shrink Connector Insulators are useful as primary electrical insulation for all solid dielectric (rubber and plastic) insulated wire and cable splicing rated to 1000 V, both indoor and outdoor. They are often good in providing physical protection and environmental sealing for communication and other non-electrical applications, including sheath repairs. Operating temperature range is -40°C to 90°C. In applications where the product is continuously exposed to UV radiation it is good to overwrap with e.g. Scotch® Super 33+™ Vinyl Electrical Tape or Scotch® Self-Fusing Silicone Rubber Electrical Tape 70.	3M™ Cold Shrink Connector Insulators 1000 V
3M™ Cold Shrink High Voltage Splice kit QS3000 72.5 kV	3M™ Cold Shrink High Voltage Splice QS3000 Series Kits are designed for inline splicing up to 72.5 kV Umax Voltage class, 1-core XLPE Crossed Linked Polyethylene cables systems with copper wire screen, lead sheath or aluminium sheath according to IEC 60840.
3M™ Cold Shrink High Voltage Termination QTEN Series Kits. 1-core copper wire, lead sheath or aluminium sheath screened cables. The product options cover power cables up to 2500 mm² in size. The QTEN series, is designed for XLPE Crossed Linked Polyethylene cables up to 72.5 kV (U_max) according to IEC 60840. The kit includes silicone Cold Shrink body with integrated silicone rain sheds with a separate Cold Shrink stress control tube. Silicone Cold Shrink tubes are included to seal on cable lug and cable sheath. The creepage current collector is included for a defined earth potential at the end of the rain sheds.	Cold Shrink High Voltage Termination kit QTEN Series 72.5 kV
3M™ Sensored Cable Accessories (SCA)	3M™ Sensored Cable Accessories (SCA) are Medium voltage cable accessories including accurate current and voltage sensors to support the grid automation. It provides high accuracy voltage, current and phase angle with real time measurements when connected to secondary equipment, like RTUs or protection relays, at the medium voltage secondary substation. Moreover with a capacitive voltage sensor, the accessories provide reliable measurements over a wide temperature range and capable to capture up to the 50th harmonic (2500 Hz), offering a unique way to measure key parameters on the grid for use in prominent use-cases such as Real time monitoring, Fault detection and location, Voltage regulation and volt-var optimisation, Power quality management and Asset health.

Insulation, Connection and Termination Solutions for Renewable Electrical System Installations

3M™ Locating and Marking System

3M™ Locators and Markers provide a complete system for locating, marking and mapping vital underground assets. From markers that give an exact path and estimated depth of underground utilities, to markers that store information, to utility locators that interface with GPS/GIS field mapping instruments, 3M offers the precision tools needed to manage your assets.

3M™ Path Marking Tape	3M™ EMS and iD Ball Marker	3M™ Dynatel™ Locator XE Series

Cable Jacket Repair

Scotch® Cable Jacket Repair Tape	3M™ Heat Shrink Tubing HDCW

Other Supplies

Vinyl Electrical Tape	Rubber Electrical Tape	3M™ Scotchflex™ Cable Tie

Thorne & Derrick are Specialist Distributors to Solar EPC’s & High Voltage Jointing Contractors working on the design, construction and maintenance of UK, European and international projects supplying an extensive range of LV HV Solar Cables, Jointing, Substation & Electrical Eqpt. Based in the UK, we are highly customer responsive and absolutely committed to providing a world-class service.

We stock LV HV Cables, Accessories & Electrical Equipment to enable the construction, maintenance and operation of utility-scale PV installations – our products connect 600V/1500V solar cables into combiner boxes, inverters, transformers and energise switchgear up to 33kV/132kV for high voltage grid connections. Since 1985, we have provided expert technical support and express delivery from extensive UK stocks to world-wide destinations.