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Onshore Construction Update

Onshore construction update - July 2019

Onshore substation

The new onshore substation is located in Burstall, near Bramford.

The substation building is complete, with commissioning activities and testing underway. The key components, including Gas Insulated Switchgear (GIS), shunt reactors, statcoms and transformers are all installed.

The GIS, which is effectively a big “on and off” switch, will receive the power from the offshore windfarm. The shunt reactors and statcoms will control and smooth the electricity and the transformers will convert the power from 220kV up to 400kV to make it suitable for transfer to the existing Bramford substation and across the grid network.

Onshore cable route

The majority of the onshore cable route runs through farmland and has been installed by digging a trench and laying ducts to house the cables. Occasionally the cable route goes under a major transport network or natural obstacle, where it was not possible to use open cut methods. In these locations the ducting was installed using Horizontal Direct Drilling (HDD) or auger bore techniques. HDD is a trenchless method, used to install ducts beneath the ground, through which the power cables for East Anglia ONE were pulled. The ducts for East Anglia ONE are all installed.

Cable installation

Installation of the 400kV cables through the pre-installed cable ducts was undertaken by Prysmian. The cables were installed in 2km sections and joined together at an underground joint bay. All 400kV cables are now in position and installation of supporting electrical equipment through adjacent ducts is nearing completion.

Testing and commissioning

The first of two export cables from the offshore windfarm to Bawdsey was laid in late 2018 and tested in early 2019. We then completed the first stage of testing of the onshore cables in spring 2019.

Installation of the second offshore export cable is underway. Once complete and tested, we will undertake testing and commissioning of the remaining onshore cables.


We have begun reinstating land along the 37km onshore cable route in areas where access is no longer required. Access to joint bays is needed until the second phase of testing and commissioning is complete.

Reinstatement includes removing our temporary stone haul road, replacing the stockpiled earth and removing the fencing which marks the boundary of our construction site. We will also resurface roads in the locations where our cable route goes under the public highway. For further updates on these locations and the traffic management required during resurfacing, please see our Road and Public Right of Way closures page.

We will return to plant replacement hedgerows and trees and have committed to providing two trees for every one tree removed.

First power from East Anglia ONE is expected later in 2019 and the windfarm is expected to be fully operational in 2020.

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