The invention relates to a multiple moving contact assembly for a miniature circuit breaker with high ratings and a thermomagnetic trip release. The moving contact part of the circuit breaker includes two independent contact arms connected in parallel and mounted on a transverse spindle of the cradle. The arms are connected to a magnetic circuit of the electromagnetic trip release by two braids situated in symmetrical lateral areas. The contact parts bear on a single stationary contact pad so as to create two contact points enabling the temperature rise to be reduced. The electromagnetic top release has a coil including a tail arranged as an adjustable support device of a bimetallic strip, through whose foot the current flows thicknesswise. The tail is provided with a hinge between the junction point of the bimetallic strip and the coil, so as to allow relative movement of part of the tail due to the action of the thermal tripping threshold setting screw, the other part connected to the coil remaining appreciably station.