A rigid joint assembly including a first and second cable core end sections of a first and second electric cables, including cores having a conductor, and an insulation system having a semi-conducting layer, an insulation layer and a semi-conducting layer. The assembly includes a joint connection, and a water tight metal casing. The casing assembly has a first and second cable entry parts for receiving the first and second cable cores having joint assembly includes first and second deformation preventing members that surround cable core end sections and includes a rigid pipe.