Avonmouth

Current construction activity

Date from	Date to	Activity
June 2021	Late 2024	Access to public footpaths and rights of way
May 2021	2024	Building new pylons
October 2021	2024	Removing existing pylons
2018	Ongoing	Roadworks and traffic management

Overview – Winter 2023

National Grid started work to build the north section of the Hinkey connection between Sandford and Seabank substations in July 2022.

We’re using 400,000 volt traditional lattice pylons in and around Avonmouth, rather than the T-pylons seen elsewhere on the Hinkley Connection route. At approximately 50 metres high, the lattice design provides the height required across the River Avon and means the 27 new lattice pylons can navigate the tighter turning angles that are needed on the route between the River Avon and Seabank substation.

In February 2022, our contractor, J Murphy and Sons, started work to modify Seabank substation and the existing electricity network, replacing nearby pylons at Crooks Marsh with new underground cables. This work is set to be completed in late 2023.

To make way for the new connection, National Grid is removing 67 kilometres of existing 132,000 volt overhead wires and 249 along the new 400,000 volt connection route.

We removed seven pylons from across the M49 in 2021. Starting this spring, we’ll take down the line of pylons between Portishead and Avonmouth substations, removing pylons from a residential area, including those near Avonmouth C of E Primary School and Daisy’s Nursery.

Thank you from everyone working on the project for your patience and understanding as we progress with this vital work to connect six million homes and businesses to new sources of homegrown, low carbon energy, and help the UK meet its net zero ambitions.

Take a look at our detailed map

Avonmouth timeline

Completed September 2020

Modify Avonmouth substation and existing overhead line to the east of the substation

Work carried out:

Replaced a small section of overhead line to the north of the substation with underground cables.
Constructed a new cable sealing end (CSE) pylon to connect the underground cables to the overhead line.
Changes inside Avonmouth substation to enable the connection of the new underground cables.
Reinstatement work including removal of the temporary construction compound and part of the haul road.

To be confirmed

Modify Seabank 132,000 volt substation and the existing overhead lines at Seabank

What we're doing:

Building a temporary construction compound and temporary entrances and access roads to allow construction traffic to enter the undergrounding site from the local highway.
Undergrounding a small section of the three existing overhead lines at Seabank. This will enable the new overhead line to pass safely overhead.
Building three pylons to connect the existing overhead lines to underground cables.
Modifying Seabank substation to enable the connection of the new underground cables.
Removing the existing overhead lines that are no longer needed in this area.

Mid 2021 to mid 2025

Build new 400,000 volt overhead line

What we're doing:

Building temporary entrances and access roads to allow construction traffic to enter site from the local highway.
Building a new overhead line from Sandford substation to Seabank substation (approximately 31.2 km).
In this area, we'll use a mix of steel lattice pylons and T-pylons.

Mid 2021 to mid 2025

Remove the existing 132,000 volt overhead line

What we're doing:

Removing the overhead line from the A368 in Sandford to Avonmouth substation, which will make way for, and minimise the visual impact of, the new connection.
Removing a small section of the existing overhead line to the east of Avonmouth substation.

To be confirmed

Modify Seabank 400,000 volt substation

What we're doing:

Extending the existing substation to enable the connection of the new overhead line.
Modifying the existing site access road.
Removing unnecessary electrical equipment.
Installing a perimeter flood defence wall with flood gates around the substation to help guard against tidal flood risk.