Where direct current is supplied to an armature and shunt field of an elevator driving-machine
motor field current sensing means shall be provided, which shall cause the electric power to be removed from the driving-machine
motor armature and brake unless current is flowing in the shunt field of the motor, except for static control elevators
provided with a device to detect an overspeed condition prior to, and independent of, operation of the governor
overspeed switch, except that
(a) a common actuating means (e.g., a governor shaft or sheave] that is not physically part of the speed-sensing devices shall be permitted for the actuation of both the speed-sensing device of the overspeed detection device and the governor overspeed switch
(b) a common mounting means shall be permitted for the speed-sensing device of the overspeed detection device and the governor overspeed switch
This device shall cause power to be removed from the elevator driving-machine motor armature and machine brake.