A mechanical latching accessory kit for a Medium Voltage contactor including one or more movable contacts connected through a mechanical link to a contact actuator moving the one or more movable contacts between a contact open position and a contact closed position. The mechanical latching accessory kit includes: a supporting interface adapted to be fixed to and removed from the Medium Voltage contactor; a latching element movable between a first operating position and a second resting position; a latching actuating system moving the latching element between the first, operating, position and the second, resting, position; the latching element being adapted, when it is in the first operating position, to cooperate with the mechanical link of the Medium Voltage contactor to latch the one or more movable contacts, and, when it is in the second resting position, to release the one or more movable contacts.