Common-box built-in plug-in circuit breaker

The utility model relates to the technical field of high-voltage power distribution equipment, in particular to a common-box built-in plug-in circuit breaker which comprises an arc extinguishing device and an isolating switch, and the isolating switch comprises a moving contact rod and a static contact assembly. The static contact assembly comprises a conductive block and at least three movable conductive contact pieces, wherein one end of each movable conductive contact piece surrounds the outer side wall of the conductive block and is evenly arranged in the circumferential direction of the conductive block. The first binding tension spring is arranged on the outer side of the movable conductive contact piece in a sleeving mode and binds one end of the movable conductive contact piece tothe conductive block, the second binding tension spring is arranged on the outer side of the movable conductive contact piece in a sleeving mode and drives the other end of the movable conductive contact piece to tightly hold