A low-voltage circuit breaker includes: at least one external conductor section from an external conductor power terminal of the low-voltage circuit breaker to an external conductor load terminal of the low-voltage circuit breaker; a neutral conductor section from a neutral conductor terminal of the low-voltage circuit breaker to a neutral conductor load terminal of the low-voltage circuit breaker; a mechanical bypass switch arranged in the external conductor section; a semiconductor circuit arrangement switched in parallel to the bypass switch; an electronic control unit; and a first current measuring arrangement arranged in the external conductor section, the first current measuring arrangement including a first shunt, which is connected to the electronic control unit. The electronic control unit actuates the mechanical bypass switch and the semiconductor circuit arrangement upon detecting a prespecifiable overcurrent that includes a short circuit current, by the current measuring arrangement.