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.