MC CHRC series residual current operated circuit breaker (herein after referred to as RCCB) is compact, light-weighted, and with an attractive outer design. This product can be easily used as a module in conjunction with other electrical products. Its function is not influenced by voltage fluctuation (i.e., independent of voltage level), and suffers very little effect from an electro-magnetic field. This product is capable of functioning normally even when only one pole is powered on.