Surface Tracking – 3M Medium Voltage 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.
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):
Contamination |
Moisture |
Voltage |
| Dirt/Dust | Rain/Mist/Snow | Electrical Stress |
| Salt | Condensation | |
| Chemicals | Fog | |
| Pollutants | Humidity | |
| Other particulates |
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
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
4.10.2024
By Chris Dodds | Sales & Marketing Manager at Thorne & Derrick International
In our latest Blog, we would like to focus on Energy Transition and the future Green direction of our business at Thorne & Derrick as members of NEPIC (North East Process Industry Cluster). NEPIC represents the largest single cluster of process, pharmaceutical and chemical companies in the UK, and is the second largest in the whole of Europe.
Thorne & Derrick International, based in the North East of England, are leading UK Specialist Distributors of products to guarantee personal safety, site efficiency and plant reliability in Harsh, High Voltage & Hazardous Areas.
Our diversity is our strength, from providing legacy asset management solutions for aging electrical infrastructure to the delivery of high voltage cable connection products to repair or energise networks from 600V to 66kV.
NEPIC Membership and their energetic corporate team have been an invaluable and a vigorous catalyst to the outstanding business and employment growth at Thorne & Derrick over recent years.
NEPIC supports the needs and interests of the process industry sector in the North East of England and exists to ensure our region thrives – lobbying for and supporting investments, innovations and opportunities with a partnership network of members.
Pictured | Thorne & Derrick at NEPIC’s flagship annual networking Event, Meet-the-Members – an opportunity to initiate new client introductions, strengthen existing relationships and gain invaluable insight into the Energy future via Main Stage talks delivered by industry leaders.
During the Event we showcased and received substantial interest in our ATEX certified range of products that provide LV & HV Power, Lighting and Heating to the emerging-energy, process and power industries.
Thorne & Derrick add premium supply-chain value to the Process Industry Sector – with an unrivalled product and service provision from locally manufactured Hazardous Area Lighting by Raytec to Cold-Shrink cable accessory products from global giant and Fortune 500 company 3M Electrical. Our business also provides design services for electric heat tracing and lighting systems for industrial and Explosive Atmospheres to ensure regulatory compliance with DSEAR and ATEX certification requirements.
We specify, supply and are Certificated to provide Installer Training for the 3M range of Cold-Shrink Medium Voltage Cable Accessories in the 11kV, 33kV and 66kV voltage classes.
A Sustainable Future for our Energy & for our Business
Our NEPIC Membership has positioned Thorne & Derrick alongside a cluster of industrial, power, process and hydrogen businesses dedicated to the decarbonisation of industrial operations through the deployment of Carbon Capture & Storage (CCS) – we are working to specify and supply compliant critical equipment to build and operate the infrastructure required to transport CO2 from emitters in the Teesside and Humber regions to a secure offshore carbon store beneath the North Sea via the East Coast Cluster and the Northern Endurance Partnership.
Image | The East Coast Cluster & Energy Transition
Net Zero Teesside
Net Zero Teesside (NZT) is a collection of industrial, power and hydrogen businesses which aim to decarbonize their operations through the deployment of carbon capture utilization and storage (CCUS).
Net Zero Teesside Power (NZT Power) is a first-of-a-kind fully integrated gas-fired power and carbon capture project and a key driving force behind plans to make Teesside the UK’s first decarbonized industrial cluster.
NZT Power’s proposed combined cycle gas turbine electricity generating station will have an electrical output of up to 860 megawatts (MW) of low carbon electricity, enough to power up to 1.3m homes per year.
NZT | The UK’s First Decarbonised Industrial Cluster
T&D are Specialist Distributors to the Process Industries – this includes the fine and speciality chemicals, petrochemicals, pharmaceuticals and polymers
manufacturing sectors.
We supply and support businesses working on the design, construction and maintenance of UK, European and international projects.
We can competently specify and competitively supply an extensive range of Hazardous Area Equipment (ATEX & IECEx) to provide Power, Heating & Lighting to the Explosive Atmospheres industries – this includes LV HV Cables, Accessories, Jointing, Substation & Electrical Eqpt from 600V to 66kV.
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.
Reliable 3M Electrical Solutions That Help Keep Your Power On
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.
3M Electrical is a trusted supplier of advanced materials for Data Centres. Long-lasting 3M electrical products are engineered to enhance performance, help improve reliability,
and offer the right protection for less downtime and fewer interruptions.
3M Electrical Products — More Uptime, Reduced Outages
Insulate, Connect, Protect & Energise
Each letter below represents an electrical construction or maintenance application. Match all letters that apply to the facility illustration to see all the places where 3M electrical products help you deliver efficient, reliable, and sustainable energy solutions.
A |
Insulate Wires and Cables • Repair and re-insulate LV cables and busbar • Repair or replace busbar insulation • Insulate and seal in harsh conditions |
| Connect Wires and Cables • Conductor to conductor (pigtail and inline) • Conductor to flat pad or pin-connection |
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Splice Cables • Splice underground buried and submerged • Splice in cable tray or ductwork • Shearbolt and compression connectors |
| Rejacket and Protect Medium Voltage Cables • Rejacket buried and submerged cable • Provide mechanical and abrasion protection |
|
E |
Terminate Cables • Terminate in switchgear • Terminate live-front busbar connections • Terminate with dead-front separable equipment connection • Terminate in outdoor pole top and substation connection |
| Motor and Equipment Maintenance • Insulate motor lead connections • Repair busbar insulation • Repair metal housing for motors and pumps |
|
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Be Safe on the Job • Equipment outlet line insulation • Personal protection |
| Protect Cables from Fire, Water or Corrosion • Resist water, oil and chemicals • Resist abrasion, puncture and cut-through • Resist pipe corrosion |
|
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Fire Protection • Protective wraps • Caulks, putties, foams and large opening solutions • Sprays, sealants and tapes |
| Locate & Mark • Map path and depth of underground assets |
|
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Maintain & More • Cable identification and cable management • Metal lubrication and rust resistance |
Voltage Rating of 3M Product Applications
Indicates High Voltage Application (69KV-145KV)
Indicates Medium Voltage Application (5KV- 46KV)
Indicates Low Voltage Application (<1000V)
Kitting & Stocking Commitment | Thorne & Derrick have expanded existing stock lines and introduced products into stock across the 3M Electrical Product range from LV to HV. From Scotch Tapes for 600V repair to QTEN for 66kV termination – we hold the deepest and broadest selection of 3M Scotch, Scotchcast and ColdShrink cable accessories in UK stock, 11kV 33kV 66kV.
| Application | 3M Solution | Faster installation | Outdoor/UV resistance | Low temps performance< 0°C | High temperatures > 105°C | Moisture/humidity | Chemical/corrosion protection | Small or tight spaces | Irregular shapes or sharp edges | No access to cable end | Mechanical protection |
| Connect | Spring Connectors | • | • | • | • | ||||||
| IDC Connectors | • | • | • | • | • | • | |||||
| Direct Bury Kits | • | • | • | • | • | ||||||
| Butt Connectors | • | • | • | • | • | ||||||
| Insulate & Protect |
Vinyl Tapes | • | • | • | • | • | • | • | |||
| Rubber Tapes | • | • | • | • | • | • | |||||
| Mastic Tapes | • | • | • | • | • | ||||||
| Specialty Tapes* | S,C | S,G,V | C,S | C,S | • | • | G,V | ||||
| Motor Lead Kits | • | • | • | • | • | • | |||||
| Heat Shrink | • | • | • | • | • | • | |||||
| Splice & Terminate |
Resins | • | • | • | • | • | • | • | • | ||
| Cold Shrink Splices | • | • | • | • | • | • | |||||
| Compression Lugs & Connectors | • | • | • | • | |||||||
| Terminations | • | • | • | • | • | • | |||||
| Separables | • | • | • | ||||||||
| Locate & Mark |
Locators | • | • | • | • | • | • | • | • | ||
| Markers | • | • | • | • | • | • | • | • | |||
| Maintain & More |
Wire Terminals | • | • | • | • | ||||||
| Lubricants | • | • | |||||||||
| Wire ID | • | ||||||||||
| Cable Ties | • | • | • |
NOTE: Products vary within each category. Not all products will be suitable for all the application requirements listed.
*Speciality Tapes coding: S=silicone, C=corrosion protection, G=glass cloth, V=varnished cambric
Thorne & Derrick supply LV HV Cable Accessories, Substation & Electrical Eqpt to EPC’s & High Voltage Jointing Contractors working on the design, construction and maintenance of UK, European and international data centre projects.
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
View our Data Centre Capability page.
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.
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.
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.
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-II  3M™ 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™ 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.
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| 3M™ Path Marking Tape | 3M™ EMS and iD Ball Marker | 3M™ Dynatel™ Locator XE Series |
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| Scotch® Cable Jacket Repair Tape | 3M™ Heat Shrink Tubing HDCW |
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| 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.
Published 12 Mar 2026
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