High voltage underground cables near Bridgwater ready to be energised

Undergrounding section of existing electricity line part of modifications to accommodate new T-pylons

On Horsey Levels north of Bridgwater, the Hinkley Connection team have been undertaking complex engineering works to modify the electricity network and connect in the southern-most T-pylons on the route. 

A key part of these works, the undergrounding of a section of existing 400kV overhead electricity line, is now complete and ready for energisation.

Attached to a rare  nine armed junction pylon,  installation of the  cable means that part of the existing transmission line  between Shurton substation to Bridgwater substation is now undergrounded . By undergrounding the line, the team has made room  for a section of the new overhead lines between Horsey and the Huntspill River to tie into the same junction tower. This section of  overhead line establishes a new connection east to Melksham substation and features the most southerly T-pylon on the Hinkley Connection route.

For many reasons, including safety, overhead lines should not ideally cross each other. To ensure the new easterly branch to Melksham could be established, circuit 2 of the line between Shurton and Bridgwater had to be undergrounded. Work to underground the 400 meter cable began in February 2023, with all trenching and ducting work completed by July 2023. 

Measuring the same as four Big Bens, stacked one on top of the other, the cable was tested successfully in January 2024. Final landscaping works and the last components to be installed were completed over the summer 2024. Site demobilisation for the cable works, is expected to be completed by mid-October 2024. 

Bethan Jones , Project Manager at National Grid said:

“This piece of engineering allows us to connect the line to Melksham and provide greater resilience across the network. Once the new  transformer at Bridgwater Substation is switched on, the cable will be energised as it is a part of the same circuit. 

Work on the overhead lines is still ongoing in the area, so residents will still see activity in the area. These works should complete by Spring 2025.”  

When completed, the new high voltage electricity line will connect six million homes and businesses to new sources of low-carbon, homegrown energy including from the new Hinkley Point C power station.