National Grid Switches on First London Power Tunnels Circuit

U.K. Energy minister Michael Shanks visited National Grid’s £1 billion London Power Tunnels 2 (LPT2) project as engineers energized the first of its six new electricity transmission circuits installed deep underground in South London.

The energization sees 2.5km of new high voltage 275kV network made live between Hurst substation and Crayford – a tunnel route averaging 35 m below ground which was completed by Christine the tunnel boring machine last year.

Shanks visited New Cross substation, a key site at which work is ongoing on the project’s two other double circuits – one between Wimbledon substation and New Cross (12km), the other between New Cross and Hurst (18km).

Also under construction on the 32.5km LPT2 route is a new substation at Bengeworth Road, which – in a U.K. first – is being built using SF6-free gas insulated switchgear technology.

The previous cables between Hurst and Crayford were reaching the end of their operational life, having been commissioned in 1967 and having served London reliably for decades.

While the old cables were buried in shallower trenches in the streets, the LPT2 network carries power in 3-m wide tunnels deep beneath the road network, with vertical shafts between 9-15 m wide and up to 55 m deep sitting above the tunnels at key points along each circuit, each one covered by a headhouse.

The headhouses and shafts provide ventilation and safe access for project teams, meaning less construction and maintenance disruption, and easier future upgrade potential.

Alice Delahunty, president of National Grid Electricity Transmission, said: “We were pleased to welcome the minister at such a milestone moment for London Power Tunnels, and demonstrate the ongoing work to reinforce the city’s network. There’s still a way to go on the project, but the Hurst-Crayford circuit seeing volts for the first time is a tremendous achievement for our National Grid teams and supply chain partners.”

Energy minister Michael Shanks said: “The London Power Tunnels show British infrastructure at its best and I congratulate the efforts of everyone involved, as this new circuit switches on to power up homes and businesses across the capital.”

Since the project to reinforce the capital’s electricity network kicked off in 2020, National Grid has worked closely with supply chain partners to keep the project progressing on schedule and within budget. Project partners include HOCHTIEF-MURPHY Joint Venture (HMJV) on the tunnels, shafts, headhouses, mechanical and electrical works; Taihan and Balfour Beatty on cable supply and installation respectively; and Linxon on substation works.

The current London Power Tunnels project is the second phase of a massive endeavor to reinforce the capital’s electricity network in readiness for demand growing in the future.

It follows the completion in 2018 of the first phase – a seven-year, £1 billion project to construct 32km of tunnels and two new substations to rewire the network in North London.