Exemplary embodiments are directed to a controller unit for a switching device. The controller unit includes a body part and an operating axle. The operating axle is connected to contacts of the switching device to adjust a respective state of the contacts between a closed position and an open position. A control axle includes a first axle part and a second axle part, the first axle part is arranged to be turned by a user, and the second axle part is functionally connected to the operating axle to turn it between the open position and the closed position. A tripping assembly is functionally connected to the operating axle to turn the operating axle from the closed position to the open position. The controller unit also includes connecting means for functionally connecting a first axle part to one of a tripping assembly and a second axle part.