11kV Cable Joint – Mankind Beats Nature In Muddy Joint Hole

Published 12 Feb 2018

• Application: Jointing 11kV Cables Using Heat Shrink Cable Joints
• Product Type: 11kV Cable Joint
• Cable Jointer: Robert Coleman Director at Power Jointing Services Ltd

• by Chris Dodds T&D - estimated reading time 5 minutes  

Special thanks to Robert Coleman for his step by step explanation about the processes involved in this type of 11kV joint installation – with over 30 years cable jointing experience at 11/33kV Robert is qualified to explain the skills and techniques required to effectively work on medium/high voltage power cables in challenging workplace locations.

11kV Cable Joint

It was the morning after the day from Hell with 60mph gusting winds and rain lashing sideways from bleak skies – not the conditions for comfortable 11kV jointing. The bottom of the cable joint hole was 6 inches deep in slop so first job to do was to dig a small sump hole and bail out the excess water. Wooden blocks were used to elevate the cleaned down 11kV cables and keep them out of the mud bath.

The 11kV cable is the relatively new UKPN standard – aluminium wire screen 11kV Triplex with 300sqmm conductors and jointed using UKPN Issue Tyco SMOE 64541 heat shrink cable joints in an underground cable trench.

Alroc – Cable Tools (LV MV HV EHV Cable Jointers Tools)

11kV Jointing Tools

Using the correct cable jointing tools is critical – failure to achieve semicon screen cut perfection and excellent insulation removal will compromise life cycle of the cable accessory and ultimately cable circuit.

Alroc PG3 cable strippers were used for ringing off and stripping the outer MDPE cable sheath to the dimensions shown in the jointing instructions.

The Alroc semi con stripper is used on the fully bonded semicon screen layer to 40mm from the aluminium wire screen cut.

The Alroc insulation stripper is set at 60mm and used to remove cable core insulation to desired length of the mechanical shearbolt connector. A thorough clean of the XLPE insulation with PF impregnated cable cleaning wipes working from the insulation cut towards the semicon ensures all traces of the semicon have been removed.

A light blow over with a slack flame from a gas torch is required to dry residue from the cable wipe – then apply the yellow void filler at the screen cut to dimensions in the instructions. A stress control tube is then applied in line with the insulation cut and heat shrinked using a slack flame working toward the aluminium wire screen.

Aluminium screen wires are bent back and stripped so the semicon layer is exposed.

A build up of black tape is used and then the brass ring slid onto the cable and over the black tape for a snug fit – the wires are brought down onto ring and temporarily secured with black and red heat shrink tubes.

Once the heat shrink tubes are applied then the 11kV shearbolt connectors can be “snapped off” in sequence – use putty to fill voids in the cable connection then black void filling mastic is applied over the bolts and around the connector. Next slide black and red heat shrink tubes over the shearbolt connectors and heat shrink using a slack flame working from the centre and around the 11kV cable.

Once fully shrunk allow the 11kV joint to cool before the copper braid tape is applied half lap, side to side, of the cable joint and the copper braid secured down on both sides of the aluminium wire screen with Jubilee clips. Repeat this process on the other 11kV cores before finally wrapping the last copper braid tape around the whole cable joint, half lap and securing at the end with a half hitch.

Thorne & Derrick International

Should you require any assistance with the selection or specification of Prysmian cable joints please do not hesitate to contact us.

T&D distribute the most extensive range of MV & HV Cable Joints & Terminations, Cable Installation Accessories & Cable Pulling Equipment – we service UK and international clients working on underground cables, overhead lines, substation earthing and electrical construction at LV, 11kV, 33kV and EHV transmission and distribution voltages.

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