National Grid's London power tunnels project

Deep beneath the busy streets of north London, one of the largest engineering projects that the capital has seen in the last 50 years has reached a major milestone. Last month at an underground site beneath Haringey, National Grid began assembling a 100m-long tunnel boring machine (TBM) - nicknamed ’Cleopatra’ by local school children - that will spend the next four years creating the passages that will carry London’s future electricity supply.

London currently accounts for 20 per cent of the UK’s electricity usage - a demand that is increasing by between three and five per cent every year. In order to supply the city’s substations with the necessary energy to keep up with demand, National Grid is constructing more than 30km of underground tunnels that will carry the 400,000V transmission line cables needed. One of the tunnels will also carry additional 132,000V cables to supply the distribution networks and so will need to be a metre wider.