A motor operator for switchgear for mains power distribution system, the switchgear comprising: a cabinet with at least one operating shaft for at least one mains switch located inside the cabinet, said operating shaft having a coupling part (5,5')accessible on a front surface of the cabinet and said operating shaft being rotatable between at least two positions namely corresponding to a closed and an open position of the mains switch the motor operator comprising: a separate worm gear housing having a front surface and rear surface a rotatable connection shaft with a first and second end said first end being designed for engagement with the coupling part (5,5') of the operating shaft of the switchgear, said connection shaft rests in a hole in the front surface of the separate worm gear housing, an electric motor (27,28), and where there in the front surface of the housing is an opening for the connection shaft, a worm gear with a worm and a worm wheel said worm being in driving connection with the motor for rotating the connection shaft wherein the worm wheel (16,57) and the worm are embedded in a separate worm gear housing (11,44), a drive end of the worm is accessible from the outside of the housing (11,44) for connection with the motor (27,28), and an adapter (21,60) is fixedly connected to the second end of the connection shaft, characterized in that the separate worm gear housing comprises a side surface connecting the front surface and the rear surface, and in that there is a recess (20,61) in the worm wheel (14,57) for rotational interlocking connection of the adapter with the worm wheel. a cabinet with at least one operating shaft for at least one mains switch located inside the cabinet, said operating shaft having a coupling part (5,5')accessible on a front surface of the cabinet and said operating shaft being rotatable between at least two positions namely corresponding to a closed and an open position of the mains switch the motor operator comprising: a separate worm gear housing having a front surface and rear surface a rotatable connection shaft with a first and second end said first end being designed for engagement with the coupling part (5,5') of the operating shaft of the switchgear, said connection shaft rests in a hole in the front surface of the separate worm gear housing, an electric motor (27,28), and where there in the front surface of the housing is an opening for the connection shaft, a worm gear with a worm and a worm wheel said worm being in driving connection with the motor for rotating the connection shaft wherein the worm wheel (16,57) and the worm are embedded in a separate worm gear housing (11,44), a drive end of the worm is accessible from the outside of the housing (11,44) for connection with the motor (27,28), and an adapter (21,60) is fixedly connected to the second end of the connection shaft, characterized in that a separate worm gear housing having a front surface and rear surface a rotatable connection shaft with a first and second end said first end being designed for engagement with the coupling part (5,5') of the operating shaft of the switchgear, said connection shaft rests in a hole in the front surface of the separate worm gear housing, an electric motor (27,28), and where there in the front surface of the housing is an opening for the connection shaft, a worm gear with a worm and a worm wheel said worm being in driving connection with the motor for rotating the connection shaft wherein the worm wheel (16,57) and the worm are embedded in a separate worm gear housing (11,44), a drive end of the worm is accessible from the outside of the housing (11,44) for connection with the motor (27,28), and an adapter (21,60) is fixedly connected to the second end of the connection shaft, characterized in that the separate worm gear housing comprises a side surface connecting the front surface and the rear surface, and in that