The pyrotechnic isolating apparatus (1) for isolating a conductor (8) using an isolating punch (14) has a housing, in which the isolating punch (14) is routed, and an ignition unit (6) for driving the isolating punch (14). According to the invention, a quenching means (13) for suppressing or quenching an arc is arranged between the isolating punch (14) and the ignition unit (6). Therefore, the quenching means (13) also transmits the drive force to the isolating punch (14). The isolating punch (14) can have at least one cutting edge, so that a printed circuit board (18) is stamped out of the conductor (8) and the conductor ends (8a, 8b) are at a large distance. The isolating punch (14) is preferably composed of electrically conductive material with a melting point of greater than 2000° C. It is advantageous when a thrust piston (12) is provided between the ignition unit (6) and the quenching means (13) in order to shield the hot combustion gases from the quenching means (13). In order to brake the isolating punch (14), a damping element (16) can be provided on the opposite side of the conductor (8). When the isolating punch is at a lateral distance from the housing at least in regions there, the quenching means (13) can continue to flow even after the isolating punch (14) is braked.