An electrically insulating shell is disclosed, which includes a first half shell and a second half shell devised to be mutually connected together and shaped so as to define, once connected together, a central part delimiting a substantially closed space, which will encase a corresponding first portion of an associated electrical conductor. A first hollow portion protrudes from a first side of the central part, the first hollow portion being in communication with an inner space of the closed central part and adapted to surround a corresponding second portion of the electrical conductor. A second hollow portion protrudes from the central part from a second side opposite to the first side, the second hollow portion being in communication with the inner space of the closed central part and adapted to surround a corresponding third portion of the electrical conductor.