A circuit breaker is proposed, comprising a live line and a neutral line and a semiconductor switching unit located in the live line, the circuit breaker further comprises a bypass line, which is connected in parallel to the semiconductor switching unit, with a first mechanical switch and a second mechanical switch located in the bypass line, with the first mechanical switch connected in series to the second mechanical switch, whereby the semiconductor switching unit, the first mechanical switch and the second mechanical switch are controlled by a processing unit of the circuit breaker, which is embodied to send a first opening command to the first mechanical switch in case of a short-circuit-detection, and sending a second opening command to the second mechanical switch a time-delay after sending of the first opening command.