Abstract: A circuit breaker having a switch rated current setting on an electronic tripping unit is described. This is suitable for all circuit breakers having an electronic tripping unit that can be removed from the circuit breaker housing after removing a seal and can be lockably parameterized at the rated current of the circuit breaker. In parameterization of electronic tripping units of circuit breakers, the possibility of unauthorized parties tampering with the tripping unit must be prevented. Therefore, the tripping unit is equipped with a monitoring circuit which prevents the possibility of parameterization of the tripping unit when there is a galvanic connection between the trip magnet and the tripping unit. This permits parameterization only when the tripping unit has been removed, i.e., only by authorized personnel.