Submarine power cable
Connecting Connecting Voltage ( kV ) Length ( km ) Year Notes
Mainland British Columbia to Texada Island to Nile Creek Terminal Vancouver Island / Dunsmuir Substation 525 Twelve , separate , oil filled single-phase cables . Nominal rating 1200 MW
Tarifa , Spain ( Spain - Morocco Interconnection ) Fardioua , Morocco through the Strait of Gibraltar 400 26 1998 A second one from 2006 Maximum depth : 660 m ( 2,170 ft )
Norwalk , CT , USA Northport , NY , USA 138 18 A 3 core , XLPE insulated cable
Sicily Malta 220 95-kilometre ( 59 mi ) 2015 The Malta-Sicily interconnector
Mainland Sweden Bornholm Island , Denmark 60 43.5-kilometre ( 27.0 mi ) The Bornholm Cable
Mainland Italy Sicily 380 38-kilometre ( 24 mi ) 1985 replacing the Pylons of Messina
Germany Heligoland 30
Negros Island Panay Island , the Philippines 138
Douglas Head , Isle of Man , Bispham , Blackpool , England 90 104 km ( 65 mi ) 1999 The Isle of Man to England Interconnector , a 3 core cable
Wolfe Island , Canada for the Wolfe Island Wind Farm Kingston , Canada 245 7.8 km ( 4.8 mi ) 2008 The first three-core XLPE submarine cable for 245 kV
Operational submarine power cables -- Alternating current cables
Alternating-current ( AC ) submarine cable systems for transmitting lower amounts of three-phase electric power can be constructed with three-core cables in which all three insulated conductors are placed into a single underwater cable . Most offshore-to-shore wind-farm cables are constructed this way . For larger amounts of transmitted power , the AC systems are composed of three separate single-core underwater cables , each containing just one insulated conductor and carrying one phase of the three phase electric current . A fourth identical cable is often added in parallel with the other three , simply as a spare in case one of the three primary cables is damaged and needs to be replaced . This damage can happen , for example , from a ship 's anchor carelessly dropped onto it . The fourth cable can substitute for any one of the other three , given the proper electrical switching system .
A submarine power cable is a transmission cable for carrying electric power below the surface of the water. These are called submarine because they usually carry electric power beneath salt water (arms of the ocean, seas, straits, etc.) but it is also possible to use submarine power cables beneath fresh water (large lakes and rivers). Examples of the latter exist that connect the mainland with large islands in the St. Lawrence River.