The project
Latest update – September 2025
In May 2025, we issued a community newsletter and held information events in the community to update on our latest proposals. You can find out more about our plans on this website.
In line with Welsh Government legislation, we are now carrying out four separate statutory Pre-Application consultations for the main elements of this reinforcement and refurbishment project, including:
- Replacing underground cables and installing new underground cables at National Grid’s existing Pentir Substation.
- Constructing a new substation south of Bryncir and installing 132kV underground cables from the substation towards an existing SPEN overhead line.
- Underground cabling works and installing a new shunt reactor and other infrastructure at National Grid’s existing Trawsfynydd Substation.
- Extending the existing Wern Cable Sealing End Compound (CSEC); constructing a Tunnel Head house and CSEC; replacing the existing underground Glaslyn Cables including the removal of redundant sections of cable; and the removal of the existing Garth CSEC.
The consultations opened on Thursday 18 September 2025 and will all close at 11:59pm on Wednesday 15 October 2025.
You can view the draft application documents associated with these consultations on the Documents page of this website.
When the consultations close, we will carefully consider all the feedback received as we finalise our planning applications. We then expect to submit the four final planning applications to Cyngor Gwynydd and Eryri National Park later this year.
More information about the other permissions we need are set out on this page below.
We will continue to keep the local community up to date as our work progresses.
If you have any questions about these consultations, the consultation process or accessing the documents, please call or email us using the contact details on the right-hand side of this page.
National Grid needs to reinforce and refurbish parts of the existing high voltage power network in North Wales. This work is part of The Great Grid Upgrade- the largest overhaul of the grid in generations.
Enabling a clean energy future for Wales
National Grid needs to reinforce and refurbish parts of the high voltage power network in North Wales.
The way electricity is generated in the UK is changing rapidly to a cleaner, more affordable and more secure energy system for the future.
It is predicted that demand for electricity will at least double by 2050 as we shift to clean energy to heat our homes, drive electric vehicles and power our industry.
The Welsh Government wants to meet the equivalent of 70 per cent of Wales’s electricity demand from renewable energy sources by 2030. The UK Government has also set a commitment to reach net zero greenhouse gas emissions by 2050, and an ambition to connect 50 GW of offshore wind by 2030.
The existing transmission system was largely built in the 1960s and was designed to connect electricity mainly generated in coal-fired power stations to homes in Wales and England.
To allow new sources of renewable energy to be connected to the network, we need to reinforce and refurbishthe existing electricity network between Pentir and Trawsfynydd. This will help to keep the network secure by enabling more clean energy to be delivered to homes and businesses.
This is a major project, and it is essential that the strengthened connection is in place by 2030.
This is part of The Great Grid Upgrade, the largest overhaul of the electricity grid in generations, comprising 17 major infrastructure projects across Wales and England. Progress towards green electricity is the most effective way to ensure energy affordability, with homegrown renewable power expected to help to lower energy bills in the long term.
You can read more about our work and our latest plans here.
We currently expect construction to start in spring 2026, though this is dependent on us obtaining the permissions, licences and other agreements.
Project timeline
The permissions we will need
We need planning permissions for the different elements of our project from Cyngor Gwynedd and Eryri National Park. Consent will also be required for the work from the Department for Energy Security and Net Zero (DESNZ).
We are now carrying out statutory Pre-Application Consultations for the elements of the project set out at the top of this page. These consultations are being undertaken in line with Welsh Government legislation, and we are formally consulting landowners and adjoining landowners, local councillors and community councils, as well as specialist consultees.
The consultations opened on Thursday 18 September 2025 and will all close at 11:59pm on Wednesday 15 October 2025. The draft application documents associated with these consultations on the Documents page of this website.
Comments received will be carefully considered as we finalise our planning applications prior to submission later this year.
Contact us
If you have any questions about the project, you can get in touch in the following ways:
- Call us on: 0800 915 2485
- Send an email to: [email protected]