Penrhos Substation

National Grid Electricity Transmission (NGET) is planning to build a new Gas Insulated Substation (GIS) at our former substation site at Penrhos.  The original substation that served the old Anglesey Aluminium plant was decomissioned in 2009 and the main buildings were removed in 2024.

We are building the substation in response to connection requests for renewable energy and a new business development. NGET have a legal obligation to connect customers to our network when a connection is requested.

Penrhos substation works

The Isle of Anglesey County Council (IACC) confirmed that this work is classed as Permitted Development under the Town and Country Planning (General Permitted Development) (Amendment) (Wales) Order 2019. This means that planning permission is not required for the construction activities.

As part of the project, we will also be replacing approximately three kilometres of existing underground electricity cable that previously connected into the former substation.

Construction

Timeline

Below is our construction timeline:

• March 2026 - Site preparation complete
• July 2026 - Construction works start
• April 2028 - Cable system ready for energisation
• July 2028 - Substation ready for energisation
• Summer 2028 - All works complete

What to expect during construction

Please be assured we will work to minimise the impact of our essential works on the local area and community and will keep you informed.

During the construction period, residents may notice:

• Construction vehicles and workers accessing the site
• Increased activity during standard working hours (7:30am - 5:30pm)
• Temporary traffic management along sections of the cable route, where required for safety 

If you have any questions or concerns about construction activities, please get in touch with the project team using the contact details above.