A high-voltage switching device comprising: - a current interruption assembly comprising at least one vacuum chamber which is positioned inside said outer casing, a fixed contact assembly comprising a first fixed contact and a second fixed contact positioned inside said at least one vacuum chamber, a first movable-contact assembly and a second movable-contact assembly comprising a first movable contact and a second movable contact respectively; - a single mechanism for actuating both said first and second movable-contact assemblies (40, 50) between a first position in which said first movable contact and said second movable contact are electrically coupled inside said at least one vacuum chamber with said first fixed contact and said second fixed contact, respectively, and a second position in which said first movable contact and said second movable contact are electrically separated inside said at least one vacuum chamber from said first fixed contact and said second fixed contact, respectively, wherein said fixed contact assembly is interposed between said first and second movable contact assemblies (40, 50), and wherein said first movable contact assembly, said second movable contact assembly and said actuating mechanism are arranged so as said first movable contact and said second movable contact move, along a reference axis, one towards the other when switching from said second position to said first position and one away from the other when switching from said first position to said second position; characterized in that it further comprises an outer casing inside which said at least one vacuum chamber is positioned, a motor supplying the energy required to actuate said first and second movable-contact assemblies (40, 50), and wherein said actuating mechanism is arranged to self-lock said first and second movable contacts (41, 51) in said first position by assuming an overall position suitable to keep said first and second movable contacts (41, 51) in said first position without the need of a constraining forced exerted by the motor. - a current interruption assembly comprising at least one vacuum chamber which is positioned inside said outer casing, a fixed contact assembly comprising a first fixed contact and a second fixed contact positioned inside said at least one vacuum chamber, a first movable-contact assembly and a second movable-contact assembly comprising a first movable contact and a second movable contact respectively; - a single mechanism for actuating both said first and second movable-contact assemblies (40, 50) between a first position in which said first movable contact and said second movable contact are electrically coupled inside said at least one vacuum chamber with said first fixed contact and said second fixed contact, respectively, and a second position in which said first movable contact and said second movable contact are electrically separated inside said at least one vacuum chamber from said first fixed contact and said second fixed contact, respectively, wherein said fixed contact assembly is interposed between said first and second movable contact assemblies (40, 50), and wherein said first movable contact assembly, said second movable contact assembly and said actuating mechanism are arranged so as said first movable contact and said second movable contact move, along a reference axis, one towards the other when switching from said second position to said first position and one away from the other when switching from said first position to said second position; characterized in that it further comprises an outer casing inside which said at least one vacuum chamber is positioned, a motor supplying the energy required to actuate said first and second movable-contact assemblies (40, 50), and wherein said actuating mechanism is arranged to self-lock said first and second movable contacts (41, 51) in said first position by assuming an overall position suitable to keep said first and second movable contacts (41, 51) in said first position without the need of a constraining forced exerted by the motor.