From January 2023, we will be carrying out essential maintenance work on the 400kV overhead electricity transmission line between Twinstead Tee and Rayleigh Substation in Essex.

This essential maintenance will replace sections of wire and refurbish other parts of the overhead line. The new line will be capable of carrying slightly more power, helping transport cleaner, greener energy from where it is generated to homes and businesses.


Over the next six to eight months we will be replacing sections of overhead line, as some of the existing wires (conductors), which are bundled together to form the overhead line, are reaching the end of their asset life. We will also be replacing fittings on the pylons and repairing steelwork where necessary.

Maintenance work on one circuit between Bramford Substation and Twinstead Tee has already been completed. The remaining work will span 34km of overhead line between Twinstead and Rayleigh.

There are three sections of the route where you can expect to see works being undertaken:

  • A small section of line south of Twinstead Tee

  • Between Braintree substation and Bulls Lodge substation

  • Between Bulls Lodge substation and Rayleigh substation

This maintenance work is needed to ensure a continued, reliable supply of electricity to homes and businesses.

The new overhead lines will carry slightly more power, which will help the network as the need to carry more power out of the region grows with the increase in renewable and low-carbon generation.

Our work will not affect local electricity supplies.

What can you expect to see

We anticipate that the maintenance works will take six to eight months to complete from January 2023. We started undertaking environmental and technical surveys in September 2022, to help us prepare for the works, and anticipate that the maintenance works will be completed by late August 2023.

During this time, you can expect to see work to establish access routes, the delivery and construction of scaffolding at worksites, repairs to pylon steelwork, and linesmen working at height to replace the overhead line. Our working hours will be 7am-7pm Monday to Friday and 7am-4pm on Saturday and Sunday. Weekend works will take place every other week but can differ on bank holidays.

Before we start any work that may cause notable disruption, we will let you know through local letter drops, informing you of what we plan to do, where and for how long.

We will always aim to keep disruption to a minimum, however, we do expect there to be a limited number of road closures for a short period of time. There may also be times when we may need to install temporary traffic control measures to ensure the safety of members of the public while certain activities, such as the installation of netting, take place. If we need to close roads or put temporary traffic control measures in place, we will inform communities beforehand.

Our work will also cross some footpaths and bridleways and we may need to apply for closures on a temporary basis while we are in the area. We also anticipate that the River Chelmer will be closed to the public for a short period of time.

Project documents

Braintree to Rayleigh leaflet

Twinstead leaflet

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Our Community Grant Programme is aimed at organisations and charities in areas where National Grid’s work impacts on local people through our operations and site activities.

We fund projects run by charities and community groups that meet local community needs, by providing a range of social, economic and environmental benefits.

If your project meets our criteria, you can apply for a grant of up to £20,000.

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