A movable contact holder for a circuit breaker comprising: - a support in which a housing is provided; - a movable assembly made of electrically conductive material mounted to slide along a longitudinal axis of the support, in the housing of the support; - an upstream electrical contact pad and a downstream electrical contact pad carried by the movable assembly; - a spring exerting a restoring force (Fr) on the movable assembly, - the support further comprises two oblong holes opening into the housing and extending along its longitudinal axis; - the movable contact holder further comprises a guide shaft which is fixed in translation with respect to the movable assembly, which extends along an axis parallel to a transverse axis of the support and which is engaged in the oblong holes of the support; - the guide shaft engaged in the oblong holes guides the translation of the movable assembly in the housing; - the movable assembly is rotatable, relative to the support, about a main axis of the guide shaft; characterised in that: - the movable contact holder comprises a clevis disposed in an interior volume of the movable assembly, the guide shaft being disposed through openings in the clevis and the clevis being equipped with means for retaining one end of the spring; - the movable contact holder comprises a balancing blade disposed between the clevis and the movable assembly and interposed between the guide shaft and the movable assembly, the balancing blade being rotatable about the main axis and the guide shaft; and - the rotation of the balancing blade about the main axis of the guide shaft allows the rotation of the movable assembly about the main axis of the guide shaft. - a support in which a housing is provided; - a movable assembly made of electrically conductive material mounted to slide along a longitudinal axis of the support, in the housing of the support; - an upstream electrical contact pad and a downstream electrical contact pad carried by the movable assembly; - a spring exerting a restoring force (Fr) on the movable assembly, - the support further comprises two oblong holes opening into the housing and extending along its longitudinal axis; - the movable contact holder further comprises a guide shaft which is fixed in translation with respect to the movable assembly, which extends along an axis parallel to a transverse axis of the support and which is engaged in the oblong holes of the support; - the guide shaft engaged in the oblong holes guides the translation of the movable assembly in the housing; - the movable assembly is rotatable, relative to the support, about a main axis of the guide shaft; - the movable contact holder comprises a clevis disposed in an interior volume of the movable assembly, the guide shaft being disposed through openings in the clevis and the clevis being equipped with means for retaining one end of the spring; - the movable contact holder comprises a balancing blade disposed between the clevis and the movable assembly and interposed between the guide shaft and the movable assembly, the balancing blade being rotatable about the main axis and the guide shaft; and - the rotation of the balancing blade about the main axis of the guide shaft allows the rotation of the movable assembly about the main axis of the guide shaft.