The invention relates to a short-circuiting device for use in low-voltage and medium-voltage systems for protecting parts and personnel, comprising a switching element which can be operated by the tripping signal of a fault detection device, two mutually opposite contact electrodes having power supply means, wherein contact can be made with said contact electrodes at an electrical circuit having connections at different potentials, furthermore, in at least one of the contact electrodes, a moving contact part which is under mechanical prestress and executes a movement to the further contact electrode in a manner assisted by spring force in the event of a short circuit, a sacrificial element as spacer between the contact electrodes and also having an electrical connection between the sacrificial element and the switching element on the one hand and one of the contact electrodes on the other hand, in order to cause current flow-induced thermal deformation or destruction of the sacrificial element in a targeted manner. According to the invention, the moving contact part is in the form of a hollow cylinder which is closed on one side and a spring for generating prestress is used in the hollow cylinder. The hollow cylinder is guided in a movable manner in a complementary cutout in the first contact electrode so as to form a sliding contact. In the region of the base of the closed hollow cylinder, the cylinder wall of said hollow cylinder is configured to turn into a cone on its outer circumferential side. Furthermore, starting from the base, a first pin-like extension which is situated opposite a second pin-like projection which is insulated from the contact electrodes is arranged in the interior of the hollow cylinder, wherein the sacrificial element, in the form of a bolt or screw, is arranged between the first and the second pin-like projection. A cutout which is matched to the external cone of the moving contact and has an internal cone is provided in the second contact electrode, wherein the external cone and internal cone form a bounce-free short-circuit contact region with a force-fitting and interlocking connection on account of the plastic deformation which occurs.