Second Dinorwig-Pentir circuit energised in milestone for cable upgrade project
National Grid has switched on the second of three new high voltage electricity circuits connecting the Dinorwig hydroelectric power station with the transmission network in North Wales, marking another major step in future proofing a vital part of Britain’s electricity grid.
It follows the energisation of the first new circuit in January last year, and forms part of National Grid’s wider project to replace infrastructure originally installed in the 1970s between Dinorwig and Pentir substation.
Dinorwig pumped storage station is situated in Elidir Fawr mountain in Gwynedd, and provides fast-response power generation to help stabilise the transmission network. It is owned and operated by First Hydro, a company 75% owned by ENGIE.
Since autumn 2021, Morgan Sindall Infrastructure along with the other project delivery partner, Siemens Energy have been upgrading the connection with the transmission network to ensure clean electricity from the power station continues to flow reliably for decades to come.
Peter Kirk, managing director – Energy at Morgan Sindall Infrastructure, added:
We’re proud to be delivering this important work in North Wales, helping to bring cleaner energy onto the UK national grid and strengthen the resilience of the network. Energising the second circuit is the latest success story of strong collaboration, as we apply an innovative approach to upgrading existing circuits and boosting capacity between the Dinorwig and Pentir substations in a challenging environment.
Mark Brindley, construction director at National Grid, said:
Switching on the second new circuit is a major step forward for this project. We’re strengthening a vital clean energy link in North Wales and ensuring Dinorwig can continue to power homes, businesses and communities for years to come.
“We’re immensely grateful for the continued patience and understanding of local communities as we push ahead with the final phase of this complex once-in-a-generation project.
Delphine Cherel-Sparham, managing director of ENGIE Hydro UK, said:
It is fantastic to see the second circuit energised – another important step for Dinorwig’s future and enhanced reliability. As owner and operator, ENGIE is investing to extend the life of the station and is proud to be working with partners supporting its delivery; strengthening the flow of clean, flexible power from Wales to homes across the UK.
With the second circuit now in service, focus turns to completing the remaining new circuit and continuing work at Pentir and Dinorwig substations to further reinforce the network in the region.
Related Posts
Morgan Sindall Infrastructure launches new return to work programme
Morgan Sindall Infrastructure has formed a new partnership with STEM Returners to support more people back to the infrastructure industry after a career break. Morgan Sindall Infrastructure delivers some of the UK’s most complex…
Morgan Sindall Infrastructure completes overhead line upgrade between Harker and the Scottish border
Morgan Sindall Infrastructure has successfully completed upgrade works on overhead electricity transmission lines north of the Harker substation near Carlisle, delivered on behalf of our client, National Grid. These essential…
Morgan Sindall Infrastructure secures a position on National Grid’s New ETP
The new Electricity Transmission Partnership (ETP) will unlock long term supply chain capacity and skills across England and Wales. National Grid has introduced a transformative new approach to the way…




