§ 7.72. Electric passenger elevators.
(a) Electric passenger elevators operated by polyphase alternating current motors shall be provided with relays of the potential type or other approved devices which prevent the starting of the motor if the phase rotation is in the wrong direction, or if there is a failure in any phase.
(b) No potential difference in excess of 250 volts shall be used in connection with the car switch or automatic control circuits of electric passenger elevators. When direct current is the only available source of power supply and it is impracticable to keep within this requirement, application may be made to the Department for special permission to use a higher voltage. Full information shall be given with every application for special permit. When stepdown transformers are used in connection with alternating current car switch and automatic control circuits, they shall be of the two-winding type.
(c) The machine controllers of electric passenger elevators shall be equipped with a potential switch of either the manually or power-closing type, so designed that when the current is interrupted from any cause whatever it will automatically apply the brake and stop the elevator car.
(d) An emergency switch shall be installed in every electric elevator car except automatic control. Such emergency switch shall operate to open a main line switch independent of the car-controlling circuit wiring.
(e) When the power for elevator control circuits is dependent upon main line circuit breakers, potential switches, or other similar electric apparatus, connections shall be made so that the operation of any fire alarm system which may be connected to such main line circuit breakers, potential switches, or other similar electric apparatus, does not cut off the power to the elevator control circuit.
(f) Switches shall be provided in connection with electric passenger elevators so that the motor control circuit and the brake control circuit shall be opened before or at the time the governor trips, or, in existing installations, when the safety operates as well.
Cross References This section cited in 34 Pa. Code § 7.71 (relating to conflicts); 34 Pa. Code § 7.145 (relating to pipes and wiring); and 34 Pa. Code § 7.185 (relating to pipes and wiring).
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