A circuit breaker is for protecting a low-voltage circuit when current or current-time limits are exceeded in the low-voltage circuit. The circuit breaker includes an electronic trip unit which initiates an interruption or reduction of the current flow in the low-voltage circuit when first current or current-time limits are exceeded, and second current or current-time limits stored in the electronic trip unit, which are characterized by lower current limits or lower current-time limits, the second limits being activatable by an initiated switchover. A communication unit connected to the electronic trip unit is provided, which enables wireless communication, and the circuit breaker is designed such that when a wireless communication signal is received that exceeds a field strength value, the second limits are activated.