In the switched-on position, under the influence of contact forces generated by elastic deflection or else by mechanical spreading, or spreading caused by the attraction of parallel currents or repulsion of antiparallel currents, of a switching pin (5) , the switching pins presses against the inner side of a first switching ring (4), which is rigid for the purpose of avoiding mechanical overloading and securing sufficient consumable reserves. By way of example, a support (30) of the switching pin (5) is adjoined by two parallel, elastic extensions (52a, 52b), which are separated by a slot (53) and respectively support a contact member (54a; 54b) by means of a connecting element (55a; 55b) forming half a screw thread, with the result that said contact member is in each case offset by 180.degree. relative to the extension (52a; 52b). In the switched-on position, therefore, the contact members (54a, 54b) are forced apart by the elastic deformation of the extensions (52a, 52b) which is caused by the attraction between the parallel partial currents through said contact members. The switching pin (5) is electrically conductively connected to a second switching ring (6), which is separated from the first switching ring (4) by an arc space.