National Grid has activated one side of a new double‑circuit high‑voltage link between New Cross and Hurst, bringing an 18 km underground section into service across South London as part of its £1 billion London Power Tunnels 2 (LPT2) programme.

The switch‑on further strengthens the capital's electricity transmission network.

Running as deep as 50 metres, the live circuit replaces one of two underground cables that have served the city since the 1960s. The second New Cross–Hurst circuit is due to follow in the new year, completing the replacement of the original links, which were almost 22 km long and, until now, the longest AC transmission cables on the England and Wales system. That title will pass to the Elstree to St John’s Wood circuit in the north of the city.

The new link supplies approximately 340,000 properties in South East London, feeding UK Power Networks’ distribution system via National Grid's substations at New Cross and Hurst.

-- Advertisement --

Two earlier LPT2 circuits between Hurst and Crayford were energised in August 2024 and March 2025 along a 2.5 km stretch at the project’s eastern end.

Launched in 2019, LPT2 spans 32.5 km of tunnels across seven South London boroughs from Wimbledon to Hurst, delivered with partners HOCHTIEF‑MURPHY Joint Venture (HMJV), Taihan, Balfour Beatty and Linxon.

Deputy Mayor of London for Energy and Environment, Mete Coban, said: "It's fantastic to see electricity flowing through a new part of the London Power Tunnels. This circuit ensures homes, schools and local communities in South London are one step closer to having the power they need for the future, as we continue building a better London for everyone."

Joe Senior, project director at National Grid Electricity Transmission, said: "Switching on this circuit on a new part of our London Power Tunnels 2 project is a significant achievement for our engineering and delivery teams. This milestone in the project marks another step in reinforcing London's electricity network and keeping the city connected to safe and reliable power into the future."

Key facts from the programme include 32.5 km of tunnels; 200 km of high‑voltage cable installed — enough to reach from London to Cardiff or circle the M25; an average tunnel depth of 30 metres, with crossings beneath rivers and railways including the Northern and Victoria Underground lines and the DLR; outreach that has engaged 147,000 students through a schools programme; £525,000 awarded to local community groups such as a Lambeth food‑growing charity and Bexley Cricket Club; and more than 5 million working hours contributed by over 3,000 people since 2019.

LPT2 is the second phase of work to reinforce London’s electricity network, following the first phase completed in 2018 — a seven‑year, £1 billion project that built 32 km of tunnels and two substations to rewire North London.