In Spring 2020 we embarked upon a £1 billion project to rewire South London via deep underground tunnels. In total, 32.5km of 3m diameter tunnels are being constructed deep below the road network between Wimbledon and Crayford, which will carry high voltage electricity cables.

Works at our Wimbledon substation were completed following the arrival of the Tunnel Boring Machine (TBM) ‘Caroline’ in July 2022. A new headhouse has been completed in 2023 – it is required for ventilation and as a permanent point of access for the tunnel once it is built. The only works remaining will be minor cable installation at the end of 2024.

Our works have been carried out under our permitted development rights and have been agreed with the London Borough of Wandsworth.

The LPT project, designed to bolster London's electricity network in response to increasing demand and support a net-zero future, is set to be fully operational by 2026.

Key facts

  • Dimensions: The shaft is approximately 15m in diameter and 35m in depth. The headhouse has a maximum footprint of 16m long by 16m wide, reaching a maximum height of 10m.
  • Access: Access to the headhouse and shaft is through the substation via Copper Mill Lane. Riverside Road will be used as a second access option only.
  • Traffic:  There is currently no increase in traffic to the site expected.
  • Working hours: Our current working hours are:
    • Monday – Friday: 7am to 5pm, however no work at the site is currently expected until late 2024.


  • May 2022 – Works began on site
  • Summer 2022 – Works to the existing headhouse building were carried out, including the removal of the roof
  • July 2022 – TBM breakthrough from Kings Avenue site
  • Early 2023 – Tunnel repair works, cable bracket installation and final fittings to the tunnel 
  • Autumn 2023 – Tunnel boring completed along entire route of project
  • Late 2023 – Headhouse construction completed 
  • January 2024 – September 2025 – Site will be occupied
  • 2026 – Project expected to be fully operational 


Our site in Wimbledon is located next to Wimbledon Football Club, the River Wandle and Garratt Business Park, in the London Borough of Wandsworth.

Community involvement

National Grid is committed to working with and supporting the local communities around its project sites. To support communities around the LPT project, National Grid and our partners are delivering:

  • Outreach programme: An engaging and impactful outreach programme for secondary school students in the local area, promoting engineering careers for our net zero future.
  • Community Grant Programme: Provision of financial support for local projects via our Community Grant Programme.
  • Volunteer days: Hands-on support provided by the project team via volunteer days conducted in the community.

In November 2023, we published a Social Impact Report for the LPT school outreach programme, which illustrates the social benefits the programme has delivered for young people across South London. Working alongside early-talent specialists, Connectr, we have supported over 100,000 young people during the initial three and half years of the programme – achieving our ambition of engaging over 100,000 students before 2025.

You can read the full Social Impact Report by clicking here.


Field worker inside london power tunnels

Contact us

If you would like to discuss the project in greater detail or have any questions, please contact our community relations team using the details below:

Call our Freephone helpline number: 0800 783 2855 (lines open 9am to 5pm, Monday to Friday)

Email: [email protected]