A mechanical switch is provided which, in a first position connects a current limiting circuit to a motor and, in a second position, disconnects the current limiting circuit from the motor. Mechanical activators are provided for the mechanical switch, to switch it from the first to the second position when the tool including the motor has a predetermined relationship to the workpiece. The mechanical activators provided for the mechanical switch operate the switch either when correct positioning of the tool relative to the workpiece results in a predetermined force being applied to the activator by the workpiece or when a shaft of the tool transmits a predetermined torque.