Underground cables between Nailsea and Portishead
In August 2021, our contractors J Murphy and Sons finished installing 10.5 kilometres of 132 kV underground cables between the west end of Nailsea and Portishead substation. Laid out, these cables are a distance of 63 kilometres.
Building on this work, the team has since energised two circuits, meaning they are now in service.
World’s first T-pylons
In September 2021, National Grid and Balfour Beatty completed the foundations and piling work for 48 of the world’s first T-Pylons, from Bridgwater to Sandford. They went on to construct 19 of these ground-breaking pylons and have partly built a further 14 of the 116 that are planned for the 57-kilometre route.
We also removed 88 per cent of existing overhead wires between Bridgwater and Sandford, which span the Mendip Hills Area of Outstanding Natural Beauty (AONB) and 15 of the 24 pylons along this stretch.
World's first T-pylon erected in Somerset
The team at Shurton substation installed 18 gas insulator switchgear (GIS) units – sophisticated circuit breakers that improve safety on site and better protect the public against power outages. They built on this success by installing gas insulated busbars – metallic strips that allow conductors to cool down.
Throughout the year, our team at Sandford substation successfully coordinated four major deliveries of supergrid transformers and reactors.
Shunt reactor delivered to Sandford substation
Mendip Hills cable pull
In December 2021, National Grid and Balfour Beatty engineers finished installing 108 high-voltage, 400kV cables under the Mendip Hills Area of Outstanding Natural Beauty. These cables stretch a whopping 102 kilometres, the distance from Bridgwater to Gloucester!
Ahead of the works, the team conducted extensive archaeological mitigation works along Max mill lane, racking up 56,064 people hours (equivalent to six and half years). The team unearthed over 2,000 artefacts and 25 burial sites.
All 102km of cable is now in the ground under the Mendip Hills AONB
Overhead line from Sandford to Seabank
December saw our contractors complete piling works for 10 new pylons (and their overhead lines) between the Sandford and Seabank substations. As part of this work, the team has laid more than 9.7 kilometres of haul road and built 47 work areas.
Additionally, they have removed nine kilometres of conductors and 34 pylons between Nailsea and Portishead, dramatically improving views for many local residents.
Modifying the overhead line to Weston-super-Mare
Further down the road, the team started making changes to Western Power Distribution’s overhead line to Weston-super-Mare. They have already constructed the foundation and started to build nine new lattice pylons near Sandford substation.
The importance of communication
We know that our construction work impacts local communities, and we work hard to ensure that residents are kept informed. In 2021 we delivered 11 mailouts to 22,793 community addresses and hosted two community drop-in events in 2021. We also presented 22 briefings to stakeholders – including parish and town councils and interest groups – and organised two online and one in-person archaeology events.
Undertaking archaeological excavation works in the Mendip Hills
James Goode, Project Director at National Grid’s Hinkley Connection Project, said: “2021 proved to be another important year for National Grid and the Hinkley Connection Project, with several major milestones reached. We are looking forward to seeing what milestones our team will meet in the South West in 2022.”