An auxiliary/control switches kit box for a Medium Voltage switching device including one or more movable contacts operated between a contact open position and a contact closed position by a kinematic chain connected to a contact actuator. The auxiliary/control switches kit box includes: a shaped enclosure adapted to be inserted into and removed from a dedicated volume inside the Medium Voltage switching device; the shaped enclosure housing one or more auxiliary/control switches electrically connected to corresponding one or more terminal boards; the one or more terminal boards facing toward the outside of the shaped enclosure from a first face of the shaped enclosure; the one or more auxiliary/control switches each including a pair of auxiliary/control switch contacts that can be linearly operated by an auxiliary/control switch actuator between a normally open (NO) position and a normally closed (NC) position; a mechanical coupling system mechanically connected to the auxiliary/control switch actuator to linearly displace it between the NO position and the NC position; the mechanically coupling system having one or more operating levers protruding outside the shaped enclosure from a second face thereof and being adapted to cooperate with the kinematic chain of the Medium Voltage switching device and follow it during the movement from the contact open position and the contact closed position.