LONDON, Jan 22, 2026, 11:31 GMT
- National Grid said four planning applications for its Pentir-to-Trawsfynydd upgrade in north Wales have been validated
- The plan includes a 5.8-km cable replacement under the Glaslyn Estuary near Porthmadog and a new substation south of Bryncir
- National Grid is targeting construction from summer 2026, with the scheme fully operational in 2030
National Grid said four planning applications for an electricity network upgrade in north Wales have been validated by local authorities, moving its Pentir to Trawsfynydd project into formal review. The company expects decisions early this year and, if approved, construction would start in summer 2026, with full operation scheduled for 2030. 1
The step matters because grid bottlenecks are starting to bite harder. National Grid said the works would ease pressure on the existing network, support Wales’ clean power and energy security goals and reduce “constraint costs” — extra charges that build up when the grid cannot move electricity to where it is needed.
In Wales, the politics around new pylons, cables and substations is heating up too. The Welsh government on Wednesday published a report from an independent advisory group on the future electricity grid for Wales, as it looks to set “clear expectations” for new infrastructure. 2
Cambrian News reported the north Wales plans would replace and add underground cabling across Gwynedd, including work at the Pentir and Trawsfynydd substations, a 5.8-km cable replacement beneath the Glaslyn Estuary at Porthmadog between Wern and Minffordd, and a new substation south of Bryncir. 3
Validation is the first check that an application is complete and has the required documents and assessments before a council formally processes it, National Grid said. The company said it filed three applications with Gwynedd Council and one with the Eryri National Park Authority.
John Lamb, the project director, called it a “significant milestone”. He said: “We need to reinforce and refurbish the existing electricity network between Pentir and Trawsfynydd to meet rising electricity demand.”
National Grid said it held public information events in May and ran a 28-day statutory pre-application consultation in September before submitting the applications in early December. Energy Voice also reported on Thursday that the four applications had been validated. 4
But the timetable is still conditional. National Grid said the project depends on planning approvals and will also need consent from the Department for Energy Security and Net Zero for aspects of the work, with that process expected later this year. 5
The filing is part of a wider UK push to strengthen the high-voltage transmission network. National Grid runs the system in England and Wales, while SSE’s SSEN Transmission and ScottishPower Transmission own the networks in Scotland.
National Grid has branded its wider programme the Great Grid Upgrade. For the north Wales scheme, the next decision point is whether planners sign off the applications in the coming months, ahead of a start date the company has pegged to summer 2026.
