Abstract: An electrical full protection circuit breaker for interrupting a current circuit in response to an overload current, or a short circuit current, or in response to an earth leakage or fault current, includes the structural and functional combination of one or several single pole circuit breakers with an earth leakage current circuit breaker. Each circuit breaker has a narrow and compact structure and the same housing contour. The fault current circuit breaker member, which is coupled with one or more single pole circuit breakers, has its own contact interruption elements. Additionally, the fault current circuit breaker is provided in its outwardly located terminal connection zone with a freely accessible summing current transformer which is constructed as a bushing transformer.