The 380kV-crossing Berlin is the 380kV-line implemented to the largest part as ground cables through the city of Berlin. The first section was taken to 1977 in enterprise and consists of an overhead line with two circuits of the power station Reuter to the urban motorway. On this overhead line, which is beside a 110kV-powerline running in its proximity the only overhead line in the area of the former West Berlin, for the first time plastic insulators were used. From there the line runs to the transformer station Berlin center as underground cable. This cable is water-cooled and laid in an accessible tunnel. The transformer station Berlin center is laid out like the transformer station at the power station Reuter as totally enclosed SF6-insulated facility. It is like this the oldest 380kV-substation implemented in SF6-technology in Germany. After the reunification the 380kV-crossing Berlin was resumed in western direction to the transformer station Teufelsbruch and in eastern direction to the transformer station Friedrichshain. This line was laid in an accessible tunnel in up to 30 meters of depth, which is for better inspection equipped with a small railway.