Disclosed is a heavy-duty circuit breaker featuring arc blow-out. Said circuit breaker comprises a hot gas-sensitive and/or gas pressure-sensitive element (10) that is protected from a hot gas flow (8) by means of a seal (1). Advantageously, said seal (1) is embodied as a movable contactless seal (1). The seal (1) is preferably provided with a means (2a) for generating a partial hot gas flow (8a) of the hot gas flow (3), a means (2) for reducing the mass flow rate of the partial hot gas flow (8a), and a means (3) for expanding the volume of the partial hot gas flow (8a). The mass flow reducing means (2) is advantageously configured as a duct (2) while the expanding means (3) is advantageously embodied as a pressure relief chamber (3). The element (10) can be a guiding element, a contacting element, or a sealing element, for example.