Cable Pulling & Laying

Cable Socks – Proper Usage, Maintenance & Inspection for Pulling-in Cable

Thorne & Derrick | Jointing, Termination & Pulling Equipment

Cable Socks

Have You Inspected Your Cable Socks?

Inspecting cable socks (also known as a cable grip and cable stocking) is not an exact science, but is crucially important to ensure safe cable pulling operations, maximum grip strength and grip longevity. There are a number of variables that can weaken cable socks that are not immediately obvious on visual inspection. However, there are some important and simple checks that you can do routinely to mitigate product wear, deterioration and potential accidents from happening.

When inspecting a cable grip, it is critical to know the potential damage and trouble spots. Below highlights the type of damage you need to be aware of prior to beginning any pulling project with your cable socks.

CABLE Sock INSPECTION

Safety is Slingco & Thorne & Derrick’s primary concern.

The products manufactured by Slingco are safety critical and must be used by competent trained personnel – it is essential to choose the right cable grip for the job. Inspecting a cable grip is not an exact science. There are a number of variables that can weaken a cable grip that are not immediately obvious on visual inspection.

This is why we work to Factors of Safety.

It is important to know the difference between Working Load and Approximate Break Load, and how to use the Factor of Safety to calculate the Working Load Limit for the cable grip that will be utilized. To maximize grip performance, we highly recommend utilizing banding on the ends of cable grips, as shown in the figure below.

WLL = ABL ÷ FoS

Cable Grip Factor of Safety (FoS) *

• Overhead Pulling – 5 : 1
• Underground Pulling – 3 : 1
• Cable Supporting – 10 : 1

WORKING LOAD LIMIT

The Working Load Limit (WLL), sometimes also known as the safety working load, is the mass that the equipment being used can safely hold, pull, or lower without breaking. In short, it’s the maximum load that can be applied to the product safely when in general service.

The Approximate Break Load (ABL) is the load at which a new grip can be reasonably expected to break. This is measured on a straight line pull only, as side pulling, or angular loads, will produce different results.

The Working Load is calculated by dividing the Approximate Break Load (ABL) by the Factor of Safety (FoS). No component in the system should exceed the working load for the cable grip.

The Factor of Safety (FoS) is the “extra” coverage of the breaking load over the over the working load expected. Factor of Safety is often noted as “X to 1” or “X:1”. The Factor of Safety accommodates normal spikes in load tension that may occur when under load.

Note: Slingco recommends double banding the ends of cable socks.

When you are inspecting a cable sock, it is critical to be able to identify damage or potential trouble spots. The following are some of the types of damage you should be aware of prior to beginning a pulling project with your cable grips. If these are observed, replacement of grip should be considered.

Pulling & Supporting Power & Subsea Cables in the Wind Sector | These cable socks manufactured from offshore/marine grade type 316 Stainless Steel are suitable for use in the renewable energy sector in applications such as cable installation (onshore and offshore), cable support inside wind turbines and cable management – used to pull, protect and support wind turbine cables. Pictured: June 2020 : the first of two export cables, each 37 kilometres in length, has been installed at the nearshore of Thorntonloch Beach as part of construction of the Neart na Gaoithe (NnG) Offshore Wind Farm.

CABLE SOCKS & PULLING PRODUCTS LV MV HV

Complete range of LV, MV and HV cable pulling products for installation and enabling cable jointing in trench or ducts including LV, 11kV/33kV medium voltage (MV), 66kV/132kV high voltage (HV) and EHV transmission and distribution cables up to 400kV.

Thorne & Derrick distribute the most extensive range of Cable Installation & Electrical Distribution Equipment to the Power Transmission & Distribution industry in the onshore and offshore wind, solar, rail, oil/gas, data centre, battery storage and utility sectors.

We service UK and international clients working on underground cables, overhead lines, substations and electrical construction at 11kV and up to and EHV transmission and distribution voltages.

➡ See Also Further Reading

• Cable Laying, Installation & Support Products | MV HV Windfarm
• Thorne & Derrick Appointed Approved Stockist for UK Leading Cable Pulling Equipment Manufacturer
• NOF Members Thorne & Derrick and Slingco Ltd Supporting Cables in the Offshore Wind Industry

Earlier this year, Thorne & Derrick welcomed Phil Day from Slingco Limited, the world-leading manufacturer of cable pulling and support socks, swivels, cable protectors, wire rope assemblies and accessories. Phil provided an Offshore Wind focussed company presentation to our Sales Team (pictured left-to-right Sarah Henderson, Carl Cox, Jonathan Hewitt, Phil Day, Jeff Jhanke, Natalie Lundie and Chris Dodds.

Cable Rollers | Duct Rods | Cable Socks | Cable Lubricant | Duct Seals | Cable Duct

Working Loads & Break Strength | The Key is Your Factor of Safety

Line Pulling Swivels By Slingco

Line Pulling Swivels By Slingco

Working Loads & Break Strength

Safety is critical when dealing with utility, construction or maintenance projects.

One of the main ways to ensure safety is by working within the load limits of crucial equipment. Slingco promote the safety critical role of cable support grips and the need for independent break load testing to safeguard project, people and reputations.

Swivels designed for use in stringing high tension wires for electrical transmission and distribution. Line Pulling Swivels are important in pulling when the lines develop torsion during the installation. This torsion must be released.

Use of a swivel will release torque and prevent it from reaching dangerous levels, which can cause damage to the cable or cable socks.

Slingco also offers a ‘bull nose’ style swivel designed for underground and overhead applications. All swivels are stringently quality tested and inspected to ensure optimum performance and reliability with working Loads from 10 to 134 kN.

What is Factor of Safety?

This is the factor used to ensure sufficient break load to handle working load spikes. It is critically important that all devices and tools used for pulling conductor are rated for the working loads expected on each job.

Factor of Safety (FOS) is often notated as X to 1 or X:1. It is the ‘extra’ coverage of the breaking load over the working load expected. When pulling conductor or cable, many factors impact how much load your equipment must handle.

Sometimes the conductor can get hung up on something which will cause the load tension to spike. The factor of safety helps accommodate a normal spike without dropping wire or experiencing equipment failure.

How do you determine Break Load?

Break Load must equal or exceed the Working Load x Factor Of Safety.

To help explain this, imagine the tension for a pull is calculated to be 1,800kg – this is Working Load of the pull. If the equipment used is only rated to a Break Load of 1,800kg, any variation in the load tension over the standard can cause failure. So, project designers assign a factor of safety (FOS).

• A FOS of 3 to 1 is commonly accepted in the UK for overhead line pulls. Different countries may have a different standard.

This means that the Break Load of any tool used must be 3 times the expected load tension. In this example:

Working Load of 1,800kg x FOS of 3 = Break Load of 5,400kg.
Grips and swivels would need to be selected with a break load of 5,400kg or more.

When selecting equipment for a pull, be sure you know whether items are rated at BREAK LOAD or WORKING LOAD. If rated at working load, you must know the Factor of Safety this working load is based upon to ensure it matches your project’s working load. If rated at break load be sure it meets your project’s break load including the Factor of Safety.

Here are a few common rules of thumb for the Utility industry:

Pulling & Support Grips – usually rated at approximate BREAK load. This means a factor of safety for your project must be applied. To determine the working load, divide the break strength by your project’s Factor of Safety. For example, a grip with an approximate break load of 5,400kg to be used on a project with a FOS of 3:1 has a safe working load of 1,800kgs.

Swivels – This is where it gets tricky (or trickier). Most (but not all) manufacturers will label swivels at a 3:1 FOS working load. Slingco (along with two other prominent manufacturers of swivels) go ahead and CONVERT THE BREAK LOAD INTO THE WORKING LOAD. Our 2,240kg swivel is rated for a 6,720kg Break Load – we have already built in the Factor of Safety of 3:1.

Connectors – (90 degree, Rope to Rope, Rope to Swivel): Similar to swivels these are typically listed at their rated 3:1 WORKING LOAD. Connectors are used to connect grips when pulling though a tensioner or around an angle greater than 50 degrees. Swivels should not be pulled around a tensioner. Swivels are not designed to handle the side loads experienced when going around a tensioner wheel. This can cause damage to the bearing structure within a swivel.

These are only a few of the tools used. Remember to make sure you understand how each tool is rated (Working Load at what FOS or Break Strength). The key to ensuring a safe project is making sure all tools meet or exceed your project’s Working Load.

➡ Contact Thorne & Derrick for technical support on your cable pulling, laying and installation projects.

Cable socks and support grips are available to enable the installation of 33kV 66kV array cables prior to MV HV Jointing & Terminating in windfarm towers, turbines and offshore substations.

Further Reading

• Slingco Take A Firm Grip on The Future With Cable Socks
• How To Lace Up Cable Socks By Slingco
• Cable Grips | Supporting Inter-array, Export, Umbilical & Subsea Cable Installations
• How Do Cable Socks React To Salt Water?
• Cable Laying, Installation & Support Products | Offshore Oil & Gas Cables
• MV HV Cable Laying, Installation & Support Products | Offshore Windfarms

Supplying Cable Termination, Jointing, Pull-in & Electrical Equipment up to 66kV

Specialist Distributors to the UK and international Offshore Wind & Renewable industry to provide safe and reliable LV HV Electrical Cable & Power Distribution Systems up to 66kV – we are highly customer responsive and absolutely committed to providing a world-class service. Contact our UK Power Team for competitive quotations, fast delivery from stock and technical support or training on all LV-HV products.

NOF Members Thorne & Derrick and Slingco Ltd Supporting Cables in the Offshore Wind Industry

Today, Thorne & Derrick welcomed Phil Day from Slingco Limited, the world-leading manufacturer of cable pulling and support socks, swivels, cable protectors, wire rope assemblies and accessories. Phil provided an Offshore Wind focussed company presentation to our Sales Team (pictured left-to-right Sarah Henderson, Carl Cox, Jonathan Hewitt, Phil Day, Jeff Jhanke, Natalie Lundie and Chris Dodds).

We look forward to further strengthening our position in the offshore wind sector with the support of Slingco and their team.

Thank you for visiting and updating us on the safety critical role of cable support grips and the need for independent break load testing to safeguard project, people and reputations.

Further Reading

• Slingco Take A Firm Grip on The Future With Cable Socks
• How To Lace Up Cable Socks By Slingco
• Cable Grips | Supporting Inter-array, Export, Umbilical & Subsea Cable Installations
• How Do Cable Socks React To Salt Water?
• Cable Laying, Installation & Support Products | Offshore Oil & Gas Cables
• MV HV Cable Laying, Installation & Support Products | Offshore Windfarms

Supplying Cable Termination, Jointing, Pull-in & Electrical Equipment up to 66kV

Specialist Distributors to the UK and international Offshore Wind & Renewable industry to provide safe and reliable LV HV Electrical Cable & Power Distribution Systems up to 66kV – we are highly customer responsive and absolutely committed to providing a world-class service. Contact our UK Power Team for competitive quotations, fast delivery from stock and technical support or training on all LV-HV products.

Greenlee Cable Pulling Equipment | Cable Laying Products for LV MV HV Underground Cables

Cable Pulling Equipment | Greenlee

Greenlee

In 1996, Klauke the leading manufacturer of cable cutting and crimping tools expanded its electrical product portfolio with the acquisition of the Greenlee brand – with the focus on punching tools and cable management, Greenlee supports the safe and reliable installation of electrical cables and equipment to provide power distribution at LV MV HV networks.

Speedy Spinner | Cable Pulling Device

Easy Rollers | Cable Drum Rollers 

Polyester Butler & Smart Bulter | Fibreglass Cable Pulling System

Fish Tapes | Conduit Rod Tapes 

Cable Installation Lubricant | Electrical Cable Lubrication

➡ Catalogue Download

Contact Thorne & Derrick for competitive prices, stock availability and technical customer support on the complete range of Greenlee products for Pulling & Laying cables.

Thorne & Derrick distribute the most extensive range of Low & High Voltage Cable Installation & Electrical Distribution Equipment to the Power Transmission & Distribution industry in the onshore and offshore wind, solar, rail, oil/gas, data centre, battery storage and utility sectors – this includes the most extensive range of Cable Pulling & Cable Laying Equipment to enable the installation of low, medium and high voltage power cables into underground trench or duct.

We service UK and international clients working on underground cables, overhead lines, substations and electrical construction at LV, 11kV/33kV and up to EHV transmission and distribution voltages.

Key Products: MV-HV Cable Joints & Terminations, Cable Cleats, Duct Seals, Cable Transits, Underground Cable Protection, Copper Earth Tapes, Cable Jointing Tools, Feeder Pillars, Cable Ducting, Earthing & Lightning Protection, Electrical Safety, Cable Glands, Arc Flash Protection & Fusegear.

Distributors for: 3M Electrical, ABB, Alroc, Band-It, Cembre, Centriforce, CMP, Elastimold, Ellis Patents, Emtelle, Furse, Greenlee, Lucy Zodion, Nexans Euromold, Pfisterer, Polypipe, ProGARM, Prysmian, and Roxtec.

Specialist Distributors | LV MV HV Jointing, Earthing, Substation & Electrical Eqpt

Techlube | Cable Pulling Lubricants for Power & Telecom Cables

Cable Pulling Lubricants | Techlube

Cable Pulling Lubricants

Techlube by Socomore

Techlube is a range of water-based underground Power & Communication cable pulling lubricants designed to provide superior friction reduction and reduce the risk of cable damage during cable installation, which is the primary cause of 90% of cable damage.

All Techlube cable lubricants share similar chemistries and characteristics:

• ‘Cling & String’ consistency of Techlube ensures strong adhesion to the duct wall/ cable
• Perfect adhesion to cable in wet weather
• Resistance to wash off, allowing lubrication even in flooded ducts
• Slow drying, leaving a thin film which keeps its lubricating potential assisting with cable pulls to the same duct, preventing ‘cementing’ of the cable
• Substantially biodegradable* & non-flammable
• Water polymer lubricants with low conductivity

Cable Lubricants By Socomore

Cable Pulling Lubricant Product Benefits

• Reduced friction & risk of damage
• Compatible with cable jackets & jointing accessories
• Regular pulling tension
• Temperature stability
• Retains lubricating potential
• Improved efficiency
• Environmentally responsible
• Several formulations available

Friction Reduction

The ability to reduce friction between the cable jacket and the conduit provides the means to evaluate performance of cable lubricants.

Friction Theory:

The coefficient of friction, µ is a dimensionless value that is a proportionality constant between the frictional force, F, and the normal force, N.
µ=F/N
µ_s : the static coefficient of friction, is defined as the minimal force required to start an object in motion divided by the normal force.
µ_k :the kinetic coefficient of friction, is defined as the minimal force required to keep an object in motion divided by the normal force.

Note: laboratory measured coefficients may not be accurate when used to predict actual cable pulling tensions.

Compatibility 

Techlube does not contain any salt, detergent, paraffin or grease which can degrade cable jackets or cause hot spots, and has passed compatibility testing with materials commonly used in power cable accessories, joints & cable jackets including HDPE, LLDPE, Natural Rubber, CPE, CSPE, EPR, XLPE, PVC and Neoprene.

Cable Pulling Lubricants Techlube Range

*Excluding microspheres in Techlube M

Directions For Use

Techlube products are easy to apply through a variety of methods:

• Hand
• Manual Pouring
• Pumping
• Cone Feeder Systems

Recommended Cable Pulling Lubricant Quantity

These quantities are given for reference and guidance only. Every installation is different depending on complexity, route, cable and duct variables.

• For plastic conduit (PVC, Polyethylene) use the following equation:
  Q = 0.0064 x L x D (HD, PHD, MULTI)
  Q = 0.0080 x L x D (FO)
  Q = 0.0004 x L x D (M)
• For multiple concrete, clay tile, fibre cement, fibre filled & wooden conduit use the following equation:
  Q = 0.0098 x L x D (HD, PHD, MULTI)
  Q = 0.0120 x L x D (FO)
  Q= 0.0006 x L x D (M)

Q = Quantity of Techlube
L = The total length of the pull in meters
D = The inside diameter of the conduit in centimeters

Physical Properties

Appearance: Viscous liquid
VOC: 0% or O g/1
PH: >=5.0 – <8.0

Health & Safety

• Substantially biodegradable*, non-toxic & water-based
• Non-flammable
• Not irritating to the skin under normal use
• No unpleasant odour
• Protective clothing not required under normal use
• No threat to the environment

Temperature Stability

Standard grade Techlube will not lose performance qualities in hot weather or after undergoing freeze/thaw cycles.

Clean Up

Good working practice in accordance with local & EU regulations.

Standard Packaging

• 20 litre buckets / 24 buckets per pallet
• 1 litre bottles (PHD only)/ 12 bottles per case/ 36 cases per pallet
• 2 litre pre-lube bags (HD only) / 10 bags per bucket

Storage & Shelf-Life

Store tightly sealed in adequately ventilated premises. Shelf life is one year from the manufacturing date.

General Requirements for Cable Lubricants

• Cable & Duct Compatibility: prolonged exposure to the lubricant should not adversely affect the cable or duct performance for the life of the cable
• Friction Reduction: the initial installation should not expose the cable to excessive pulling forces or generate damaging heating effects and when completely dried, the lubricant should not ‘cement’ the cable in place
• Environmental Safety: the chemical consistency of the lubricant should not adversely affect the users or environment into which it is placed
• Fire Resistance: the lubricant deposits should not continually burn or spread a flame along the length of the duct/ cable
• Electrical Considerations: the lubricant should not affect the volume resistivity of the semi-conducting cable jacket when used in conjunction with power cables

The below video shows the Socomore Techlube HD heavy duty water-based cable pulling lubricant in use. Suitable for underground cable installations and is designed for heavy power and difficult cable routes and pulls (LV HV).

Cable lubricants manufactured by Socomore are recommended when installing LV-HV power, fibre optic and telecoms cables into cable duct.

CABLE PULLING & CLEANING PRODUCTS

Thorne & Derrick International are the UK’s leading stockist and supplier of Cable Pulling & Cable Laying Equipment for the installation of underground land and subsea power cables and overhead lines up to 400kV – the products support cable pulling teams to install LV MV HV cables into trench, cable duct, risers and all forms of cable containment.

T&D distribute the complete range of LV-HV Cable Pulling and Laying Equipment including cable rollers, cable socks, cable jacks, cable drum trailers, cable lubricant, underground cable protection and conduit duct rod.