A busbar system has at least two phase conductors (3 to 5) extending along an axis through insulating bodies. The conductors are all concentric about the central axis. They are surrounded concentrically by an insulating sheath (6). The insulating bodies are between the conductors as well as being between the outermost one and the sheath. The outer surface of the sheath is either conducting or semi-conducting. The insulators are spiral ones. The conductors are assembled from prefabricated tubular sections joined by annular conducting connections. These connections take into account the thermal expansion of the conductors and are formed by inner and outer rings.
