<p>The unit (40) has a contact spring (42) accommodated in a housing (41) and comprising displays (46) provided at lateral sections of the contact spring, where the sections are provided at a distance from each other. The sections are positioned between a connection unit and contact points (45) of the spring. An element is inserted from a rear side (53) between the contact points of the spring. Elements (49) are inserted from a front side (43) between the displays of the spring. The elements are designed as separation device or testing device or splitting device or protection device.</p>
