Earthing switch for a medium voltage electric switchgear wherein said earthing switch comprises: - a plurality of moving contacts and a plurality of fixed contacts; - a frame which supports a mechanism for rotating said moving contacts between a first reference position, at which they are separated from said fixed contacts, and a second reference position at which they are electrically connected to said fixed contacts, wherein said mechanism comprises a first shaft on which said moving contacts are rigidly mounted, said first shaft rotating around a longitudinal axis in a closing direction for which said moving contacts reach said second reference position and in an opening direction for which said moving contacts reach said first reference position, characterized in that said mechanism comprises: - a second shaft coaxial to said first shaft and connectable to an operating mechanism for the control of said second shaft, wherein said first shaft is internally hollow and defines a longitudinal cavity inside which said second shaft is at least partially arranged, - first coupling means (15A, 15B) of said shafts (11,12) configured so that said second shaft is free to rotate with respect to said first shaft, for at least a first rotational phase, when said second shaft rotates according to said closing direction, said first coupling means (15A, 15B) making said shafts (11,12) rotationally connected after said first rotational phase is completed; - spring means (13A,13B) operatively connected to said first coupling means (15A, 15B), characterised in that: said spring means (13A, 13B) are loaded during said first rotational phase and release their elastic energy on the two shafts (11, 12) by means of said first coupling means (15A, 15B) when said first rotational phase has been completed. - a plurality of moving contacts and a plurality of fixed contacts; - a frame which supports a mechanism for rotating said moving contacts between a first reference position, at which they are separated from said fixed contacts, and a second reference position at which they are electrically connected to said fixed contacts, wherein said mechanism comprises a first shaft on which said moving contacts are rigidly mounted, said first shaft rotating around a longitudinal axis in a closing direction for which said moving contacts reach said second reference position and in an opening direction for which said moving contacts reach said first reference position, - a second shaft coaxial to said first shaft and connectable to an operating mechanism for the control of said second shaft, wherein said first shaft is internally hollow and defines a longitudinal cavity inside which said second shaft is at least partially arranged, - first coupling means (15A, 15B) of said shafts (11,12) configured so that said second shaft is free to rotate with respect to said first shaft, for at least a first rotational phase, when said second shaft rotates according to said closing direction, said first coupling means (15A, 15B) making said shafts (11,12) rotationally connected after said first rotational phase is completed; - spring means (13A,13B) operatively connected to said first coupling means (15A, 15B), characterised in that: said spring means (13A, 13B) are loaded during said first rotational phase and release their elastic energy on the two shafts (11, 12) by means of said first coupling means (15A, 15B) when said first rotational phase has been completed.