150-kV and 110-kV XLPE submarine cable installations between Morcote and Brusino, Switzerland

The installation of an underwater cable connection in Lake Lugano is described. The cable routing, choice of cross-linked polyethylene (XLPE) as the cable insulation, grounding system, laying methods, protection conduits, cable laying, and accessories are discussed. The submarine described has operated without incident since being placed in service in 1985. The three circuits described, which represent an innovation in submarine cables from both a product and an installation point of view, show that XLPE, when properly manufactured and used with the proper cable construction (a hermetically sealed metallic sheath), can be used as a reliable insulating material even when installed directly in water. >