Siemens 5su1356 series ground fault circuit 1 pole n tripping characteristic b siemens 5su1356 6kk20 the siemens 5su1356 6kk20 is a din rail mountable residual current operated circuit breaker rccb of characteristic type b this 20a circuit breaker is suitable for use in three phase current systems before input circuits with rectifiers it is not intended for use in dc systems and in networks with operating frequencies other than 50hz or 60hzwith type b the tripping characteristic is ad