The Helgoland cable with a length of 53 kilometers, the longest submarine cable , which completely within the German territory extends. It is a 30 kV three-phase cable for the power supply of the island of Helgoland and was manufactured in one piece by the Norddeutsche Seekabelwerke for the energy supplier E.ON Hanse . The total length (with reserve) is 55 kilometers; it replaces Heligoland's previous power supply with diesel-powered generators . In addition to a live part, the cable contains optical fibers for data traffic.
Project planning began in 2007; the relocation was planned for spring 2009, but had to be postponed four times due to bad weather. On June 6th, 2009 the cable layer Nostag 10 finally started work from St. Peter-Ording , after 12 (planned 21) days it reached Heligoland. The cable was washed into the sandy seabed about 1.5 meters deep. Since September 2009, after all connections have been completed, Helgoland has been the last German municipality to be connected to the European network.
