an operating mechanism for a circuit breaker comprises : an operating handle movable between on and off positions extending substantially up at a point between the on and off positions ; a crank for controlling a contact arm of the circuit breaker to cause the contact arm to move between open and closed positions ; mechanism spring connected between the operating handle and the crank , causing said crank to move when discharged and when the operating handle is moved between said on and off positions ; a trip latch configured to restrain the mechanism spring from discharging unless moved ; and means for moving the trip latch upon removal of an electronic trip unit .