Melksham 66v bulk supply point

Installation of double circuit 66kv cable system at Melksham

Project outline

As part of the EPC major underground circuits framework, National Grid was required to provide Network Rail with an 88MVA BSP connection to support the electrification of the Great Western Mainline. Melksham is one of the supply points for the London to Cardiff line.

Key challenges

The project was to provide and install a fully ducted double circuit 66kv cable system. The route predominantly runs through agricultural land, comprising fields and watercourses. A key challenge was to lay the cable in an efficient and sustainable manner whilst

The challenge faced was how to dig, lay 10.4km of cable, and reinstate the cable trench in an efficient and sustainable manner with the highest standards of health and safety.

Project delivery and innovations

Murphy devised, designed and fabricated a bespoke pipe laying system for this project. The ‘safe dig technology’ eliminated the need for operatives to enter the trench and didn’t require wooden trench support. This technology allowed up to 700m of ducting to be laid per day, reducing the health and safety risks to operatives and also the overall time needed to complete the job by 70%.

Other innovations included onsite batching of cement bound sand (CBS) and the introduction of an aluminum conductor works. The CBS was delivered in bulk from a local source and batched on site using a mobile batching plant, this reduced transport movements, wastage and down-time as fewer trips were required to and from site.

Key facts

  • Up to 700m of ducting laid per day using ‘safe dig technology’
  • Vehicle emissions halved due to the use of onsite CBS batching



National Grid


Melksham, Wiltshire

Completion Date

March 2016



Capabilities Demonstrated

  • Power systems engineering

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