11kV Cable Installation At Carnaby Street

Published 20 Apr 2021

Images Courtesy of: Declan Scully – AP, SMSTS, HV Electrical Fitter and Electrician at UK Power Networks

Pictured: 11kV cables installed using cable cleats manufactured by Ellis Patents

WHAT ARE CABLE CLEATS?

Cable cleats are used to fix, clamp and support cables – cleats provide effective short circuit protection, support and retention to LV, MV and HV power cable systems when installed at intervals to circuits to secure electrical installations.

The cable cleats provide restraint and prevent excessive cable movement resultant from fault-current magnetic forces – cleats must be suitably rated for cable size (outside diameter) and anticipated fault current (peak fault level kA).

Correctly specified cable cleats will withstand the forces corresponding to the values of the peak prospective short-circuit current.

Power cable system designers, engineers and specifiers must consider the correct cable fixing or securing system to provide safe and adequate restraint and protection of LV, MV or HV cables – cable cleats restrain movement of cables during electrical fault conditions.

Cable cleats are available to suit all environmental conditions (onshore and offshore), industrial applications and operating voltages – specialist cable fixings for fire resistant, low smoke zero halogen (LSF LSOH) and quadrafoil (Quad) cable installations.

“Every conductor or cable shall have adequate strength, and be so installed as to withstand the electromagnetic forces that may be caused by nay current, including fault current.” IET Wiring Regulations 17th Edition BS7671:2008 (2011). 

CABLE CLEAT SPECIFICATION

Selection of cable cleats should consider several key factors:

• Cable Diameter – the overall diameter of the LV-HV cable ensure the correct size of cleat is chosen. This dimension, namely the outside cable diameter around the cable sheath, is also required for calculating short circuit forces the cleat could potentially be subject to under fault conditions.
• Performance – depending on the cable installation application there may be a requirement for the cleat to include material performance and specification features, for instance fire resistance, LSF (Low Smoke Fume), LSOH LSZH (Low Smoke Zero Halogen) or corrosion resistant (stainless steel)
• Cable Type – check cable voltage and construction: LV Low Voltage, MV Medium Voltage or HV High Voltage.

Thorne & Derrick | Ellis Patents UK Distributors

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