An operation mode selector for an earthing switch disconnector, the earthing switch disconnector including power contacts and a motor to manipulate the power contacts, the selector including a knob capable of taking a plurality of positions respectively corresponding to different operation modes of the earthing switch disconnector, characterised in that it includes: cams rotatably driven by the knob of the selector, the operation modes of the earthing switch disconnector including an automatic mode in which manipulating the earthing switch disconnector is performed using the motor, a manual mode in which manipulating the earthing switch disconnector is performed by an operator, and open locked and closed locked modes in which the open and closed positions of the earthing switch disconnector are respectively locked, a first cam which drives a first rotatable locking member intended to mechanically block the motor of the earthing switch disconnector when the knob of the selector is in one position of the plurality of positions corresponding to the closed locked mode, a worm screw rotatably driven by the motor and a nut driven by the worm screw when the motor drives the worm screw, the nut being connected to a control shaft to cause the power contacts of the disconnector to move, the disconnector being installed into a cell including a detachable electrical appliance mounted to a carriage, and a first lever driven by the nut of the worm screw, so that the first lever acts on a second locking member so that it mechanically blocks the carriage of the electrical appliance in the detached position when the nut moves to the closing position of the disconnector, when the selector is in one position of the plurality of positions corresponding to the automatic mode. the selector including a knob capable of taking a plurality of positions respectively corresponding to different operation modes of the earthing switch disconnector, characterised in that it includes: cams rotatably driven by the knob of the selector, the operation modes of the earthing switch disconnector including an automatic mode in which manipulating the earthing switch disconnector is performed using the motor, a manual mode in which manipulating the earthing switch disconnector is performed by an operator, and open locked and closed locked modes in which the open and closed positions of the earthing switch disconnector are respectively locked, a first cam which drives a first rotatable locking member intended to mechanically block the motor of the earthing switch disconnector when the knob of the selector is in one position of the plurality of positions corresponding to the closed locked mode, a worm screw rotatably driven by the motor and a nut driven by the worm screw when the motor drives the worm screw, the nut being connected to a control shaft to cause the power contacts of the disconnector to move, the disconnector being installed into a cell including a detachable electrical appliance mounted to a carriage, and a first lever driven by the nut of the worm screw, so that the first lever acts on a second locking member so that it mechanically blocks the carriage of the electrical appliance in the detached position when the nut moves to the closing position of the disconnector, when the selector is in one position of the plurality of positions corresponding to the automatic mode. cams rotatably driven by the knob of the selector, the operation modes of the earthing switch disconnector including an automatic mode in which manipulating the earthing switch disconnector is performed using the motor, a manual mode in which manipulating the earthing switch disconnector is performed by an operator, and open locked and closed locked modes in which the open and closed positions of the earthing switch disconnector are respectively locked, a first cam which drives a first rotatable locking member intended to mechanically block the motor of the earthing switch disconnector when the knob of the selector is in one position of the plurality of positions corresponding to the closed locked mode, a worm screw rotatably driven by the motor and a nut driven by the worm screw when the motor drives the worm screw, the nut being connected to a control shaft to cause the power contacts of the disconnector to move, the disconnector being installed into a cell including a detachable electrical appliance mounted to a carriage, and a first lever driven by the nut of the worm screw, so that the first lever acts on a second locking member so that it mechanically blocks the carriage of the electrical appliance in the detached position when the nut moves to the closing position of the disconnector, when the selector is in one position of the plurality of positions corresponding to the automatic mode.