An electric switching apparatus including fixed contacts respectively supported by an upstream support and a downstream support and electrically connected to an upstream power line and to a downstream power line, respectively, the fixed contacts cooperating with respective upstream and downstream mobile contacts, each of the mobile contacts being supported by a support, the supports movable simultaneously in translation by a contact carrier controlled by an actuator. This apparatus includes a device for transforming, during a device opening operation in the presence of a microweld between one of the mobile contacts and the associated fixed contact, the movement in translation of the support associated with the mobile contact in a combined movement in translation and rotation of the mobile contact so as to exert at the points of contact between the mobile contact and the fixed contact a shear force capable of breaking the aforementioned microweld.