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.[1]
| Elstree to St. John's Wood Cable Tunnel | |
|---|---|
| Location | |
| Country | UK |
| Province | Greater London |
| Ownership information | |
| Owner | National Grid plc |
| Construction information | |
| Construction started | 2001 |
| Commissioned | 2005 |
| Technical information | |
| Type | Underground tunnel |
| Type of current | AC |
| Total length | 20 km (12 mi) |
| AC voltage | 400 kV |
The tunnel runs beneath the A5 road for the majority of its length, and houses a single 400 kV power transmission circuit with a rated capacity of 3700 A. There is provision for a second circuit to be installed in the future.[2]
A remotely operated, battery powered monorail system runs along the tunnel, allowing the cables to be inspected remotely using infrared cameras.[3]
References
edit- ^ "ABB starts to make 'The London Connection'" (Press release). 25 October 2004. Retrieved 13 January 2020.
- ^ "London extension uses biggest ever XLPE cable". Modern Power Systems. 20 April 2001. Retrieved 13 January 2020.
- ^ "The private monorail tunnel under North London". Ian Visits. 12 October 2016. Retrieved 13 January 2020.