The disclosure relates to a method for quenching a fault arc in a medium-voltage and high-voltage switchgear assembly, in which at least one shorting element is connected between the phases of a three-phase distribution board. In order to allow more reliable fault arc quenching in this case, the disclosure proposes that the fault arc is detected by means of sensors and an explosive charge which acts directly on the shorting switching element fires the shorting switching element at a conical contact structure which is connected to the three-phase conductors and is configured in a complementary manner to the shorting switching element, in such a manner that the complementary contours of the shorting switching element and of the three-phase conductors result in self-locking retention in the shorting position, without any holding force.