Electric power transmission in the United Kingdom

London Power Tunnels is a project by National Grid to reinforce the electricity transmission network in London, UK, by constructing more than 60 km of new deep-level tunnels carrying high-voltage cables.

Fawley Tunnel, or Fawley transmission tunnel, is a 3-metre (9.8 ft) diameter, 2-mile (3.2 km) long tunnel under Southampton Water between Fawley Power Station and Chilling near Warsash. It carries the cables of two 400kV circuits of the National Grid.

The River Medway Cable Tunnels are a pair of tunnels carrying high-voltage electricity transmission lines beneath the lower River Medway between the Isle of Grain and Chetney Marshes, Kent.

The Lower Lea Valley Cable Tunnels, known as the PLUG (Power Line Under Ground) Project during construction, are a pair of 6 km cable tunnels running beneath the lower Lea Valley in east London. Constructed at a cost of £130m ahead of the 2012 London Olympic Games, they are owned by National Grid plc and UK Power Networks.

The Thames Cable Tunnel, also known as the Tilbury – Gravesend Cable Tunnel, is a tunnel carrying high-voltage electrical transmission lines beneath the lower River Thames between Tilbury and Gravesend. It remains the furthest tunnel downstream on the Thames.

The Elstree to St. John's Wood Cable Tunnel, known as The London Connection during construction, is a 20 km long, 3m wide tunnel beneath northwest London. Constructed between 2001 and 2005, the tunnel carries high voltage transmission lines from Elstree substation in Hertfordshire to Lodge Road sub station in Westminster at a depth of 20m below street level.

The 275 kV Forth Crossing is an overhead power line crossing of the River Forth in Scotland. The crossing, located next to the Clackmannanshire Bridge and the Kincardine Bridge, has the tallest electricity towers (pylons) in Scotland .

In the United Kingdom, powerlines cross rivers and estuaries either in the form of overhead lines or with cables carried in tunnels. Overhead power lines are supported on towers (called pylons in the UK) which are usually significantly taller than overland pylons and are more widely spaced to cross the river in a single span. Tall pylons ensure that the electricity cables which they support provide an adequate safety clearance for river traffic.

The 400 kV Thames Crossing is an overhead power line crossing of the River Thames, between Botany Marshes in Swanscombe, Kent, and West Thurrock, Essex, England. Its towers are the tallest electricity pylons in the UK.

The National Grid is the high-voltage electric power transmission network serving Great Britain, connecting power stations and major substations, and ensuring that electricity generated anywhere on the grid can be used to satisfy demand elsewhere. The network serves the majority of Great Britain and some of the surrounding islands. It does not cover Northern Ireland, which is part of the Irish single electricity market.