About the project
The North West London Upgrade is a major investment into the electricity network running between Sundon in Bedfordshire and St John’s Wood in London.
It includes new infrastructure, such as a new substation and cables, as well as upgrades to existing substations and overhead lines.
The project will help make the network more resilient, support growing demand for electricity, and ensure homes, businesses and public services have the power they need now and in the future.
The project will be delivered in stages up to 2030, with work taking place in different areas at different times.
This is because some work needs to be completed before other work can begin, and large equipment needs to be moved safely.
We will keep communities updated as the work progresses. For information about work near you, visit the what’s happening and where page or get in touch with the team via the details listed on this website.
About the infrastructure
A substation helps move electricity safely from the national network to the local network, so it can reach homes, businesses and public buildings.
There are four substations along the NWLU route: Sundon, Elstree, Letchmore Heath and St John’s Wood.
A Supergrid Transformer (SGT) is a large piece of equipment inside a substation. It helps change electricity from a very high voltage to a lower voltage, so it can be safely passed on to the local network.
This helps electricity reach homes, businesses and public services.
SGTs are very large and heavy, so moving them to site needs careful planning with local authorities to help manage impacts on local roads.
As part of the North West London Upgrade, new SGTs are being installed at the new Letchmore Heath substation.
Cable tunnels carry electricity cables underground. This helps us to avoid digging up roads and streets for most of the work, reducing disruption for local residents, businesses and road users.
A headhouse is a small above-ground building that gives access to an underground cable tunnel. It also contains ventilation equipment to help keep the cables cool.
There are eight headhouses along the Elstree to St John’s Wood cable tunnel. They will help our teams access the tunnel during the work.
Working with communities
Biodiversity net gain means leaving nature in a better condition than before the work started.
For the new Letchmore Heath substation, we are working to delivering a 15 per cent biodiversity gain through measures such as new landscaping and planting.
Across NWLU, we will look for ways to reduce impacts and improve habitats where we can. Any biodiversity improvements must be protected for at least 30 years, so they provide long-term benefits for local nature.
Communities play an important role in the move to cleaner energy, and we believe communities hosting new energy infrastructure should benefit.
In March 2025, the UK Government published guidance for delivering community funds in areas where we need to build new onshore electricity transmission infrastructure.
This means the community around the new Letchmore Heath substation will be eligible for £530,000 to support local projects.
We will speak with local people before the fund opens to help decide who can apply, what types of projects it should support and how the money should be used. We will share more details on how residents can help shape the fund in late 2026.
Community engagement
We will keep communities informed and listen to local feedback throughout the project. We know construction work can raise questions, and we want to be open, accessible and responsive.
We will update this website regularly with information about the work taking place along the route. We will also contact residents and communities directly where work may affect them.
In areas where larger works are planned, this may include public drop-in events. In other areas, we may share information through letters, posters or other local updates.
Please get in touch if you have any questions or concerns about work in your area. You can contact the project team at 0800 331 7097 or [email protected].
The best place to find local information is the ‘what’s happening and where’ section of the North West London Upgrade website.
This section is organised by location. Each page will explain what work is happening, where and when it is planned, and what people may notice locally, such as traffic or access changes.
Because construction details vary by location, these pages will be the best source of information for your area. We will update them regularly as the project progresses.
If you cannot find what you need, or have a specific question about work near you, please contact the community relations team at 0800 331 7097 or [email protected]. We are always happy to help.
Contact us
If you'd like more information or want to speak with a member of our community relations team about the work, please:
Email: [email protected]
Phone: 0800 331 7097
Freepost: RTBU-HAYY-LCUX, 7 Bayley Street, London WC1B 3HB (no stamp needed)