Triplex Cleats – Selection Guide for Cleating 11kV BS7870 Part 4.10 Cables

Published 25 Jul 2018

Distributors for Ellis Patents Cable Cleats

uploaded by Chis Dodds – Thorne & Derrick Sales & Marketing Manager

The following post is provided to enable the selection of cable cleats to suit a standard UK DNO utility cable for medium/high voltage power systems – this type of MV HV cable commonly referred to as “Triplex” cable has increasingly replaced conventional BS6622 11kV 3 core XLPE insulated cable.

Triplex cable consists of 3 x single cores in a “twisted” spiral formation – this non linear cable orientation must be recreated into a circular formation using Triplex cable surrounds.

It is essential to effectively cable cleat Triplex cables to containment to ensure safe and reliable cable restraint in the event of a short-circuit situation – to simplify the cable cleat selection process it is a basic requirement to consider the calculated short-circuit fault current rating, installation environment and overall outside diameter of the 3 x single core cables when combined in Triplex formation.

The short circuit calculation would normally be the responsibility of the Electrical Design Engineer and can be calculated using a formula as recommended by IEC61914 the international standard which specifies requirements and tests for cable cleats and intermediate restraints used for securing cable in electrical installations.

Triplex Cables 11kV BS7870 4.10

Specification: 11kV Triplex, Solid Aluminium Conductor, Triplex Extruded Conductor Screen, XLPE Insulation, Fully Bonded Semi-con Screen, Copper Wire Screen, Longitudinal Water Blocking Tape, MDPE Cable Sheath, 6350/11000V to BS7870 Part 4. Sheath colour: Red.

Based on the following 11kV Triplex specification we can recommend and supply 3 types of cable cleat

Ellis Patents 2F Cable Cleat (Plastic)
Ellis Patents Vulcan+ Cable Cleat (Stainless Steel)
Ellis Patents Emperor Cable Cleat (Stainless Steel)

Voltage	Conductor Type	Conductor Sqmm	Nominal Conductor Diameter	Dia Over Insulation mm	Dia Over Semi-con Screen	Dia Over Cable Sheath	Diameter In Triplex Formation	Triplex Liner	2F Cleat	Vulcan Cleat	Emperor Cleat
11kV	Solid Aluminium	95sqmm	10.65mm	18.95mm	23.03mm	27.17mm	58.24mm	SFT26	2F+10	VRT+04	ES58-66
11kV	Solid Aluminium	185sqmm	14.9mm	23.25mm	27.33mm	31.67mm	68.24mm	SFT31	2F+1200	VRT+06	ES65-73
11kV	Solid Aluminium	300sqmm	19.0mm	27.3mm	31.38mm	36.12mm	77.83mm	SFT36	2F+1201	VRT+07	ES73-85

♦ Important: Manufacturers cable dimensional data and tolerances can vary by significant % factors hence critical measurements can be inconsistent – always provide manufacturers cable specification complete with construction information to ensure supply of correct cable cleats. Above is provided for guideline purposes only – check with Thorne & Derrick.

Based on the above cable dimensions we can supply the range of cable cleats listed below.

Triplex Liner & Cable Surrounds

Ellis Patents Triplex cable surrounds are manufactured from LSF Zero Halogen Polymeric material and used within single cable cleats to secure triplex cables – the cable liner surrounds have a maximum short circuit test level of 76kA when used with Ellis Patents 2F cable clamps and 600mm cleat spacings.

Triplex Cleats

The following table provides an overview of the Ellis Patents range of Triplex cable cleats depending on levels of short circuit fault protection required by the clamps.