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Rewiring London

London Power Tunnels is an ambitious £1 billion project to meet London’s growing demand for power. It’s also a significant engineering task that’s engaged local people every step of the way.

Deep under London’s busy streets, a 32km network of tunnels snakes its way across the capital. The reason? We’re creating a new electricity superhighway that will keep Londoners connected to safe and reliable power well in to the future.

This is the first major investment in London’s electricity system since the 1960s. And it’s much needed. 

Demand for power in the city is rising each year. As well as helping bolster future security of supply, the scheme will serve major projects such as Crossrail. It will also help link the city to new, renewable sources of energy.

A hidden marvel

The project began in February 2011 and is due to end next year. 

Most of the work is done deep underground to avoid disruption to daily life. The 3 and 4m wide cable tunnels run 20-60m below street level. They were carved by two giant boring machines, Cleopatra and Evelyn, named by local schoolchildren. After four years of digging, the tunnels were completed in March 2015.

Nearly 200km of 400kV cable runs through them. This is the same length as the M25. A series of 14 shafts have been sunk along the route allowing easy access and ventilation of the cables. This means we don’t have to dig up the roads if a repair is needed. We’ve also connected four existing substations and built two new ones.

Working with partners

We’ve worked closely with various stakeholders throughout the project. For example, tunnelling close to the London Underground network meant careful planning with Transport for London. We also sought and received hundreds of easements, which are required to permit us to tunnel under private land.

Engaging local people

In the past five years, we’ve welcomed 25,000 schoolchildren to events like sports days, and turned a disused car park into a small park for local people to use.

Our Energy Education Centre in Willesden, run by engineers working on the project, opened its doors to more than 8,000 pupils from across the city. This has sparked their interest in science and engineering.

We’ve also joined together with local groups to make a positive impact within neighbouring communities. For example, at our Highbury substation, we’ll be recovering more than 1MW of waste heat from our transformers. This will be used as a free source of heating by the nearby Montem Primary School.

Working closely with local communities and all our partners is crucial for National Grid. And this engagement is making sure that the legacy of the project will make a real difference to Londoners. As David Palser, Lead Project Manager, put it: “There is a true sense of pride within the team at what has been achieved. A secure and robust electricity network for London will be very much worth the wait.”

Related information

For more details on this project, visit the London Power Tunnels website.

Published: June 2017