§ 7.292. Electric freight elevators.
(a) All electric freight elevators operated by polyphase alternating current motors shall be provided with relays of the potential type, or other approved devices, which will 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 differences in excess of 250 volts shall be used in connection with the car switch or automatic control circuits of new electric freight elevators. When direct current is the only available source of power 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 each application for a special permit. When step-down transformers are used in connection with an alternating current car switch and automatic control circuits, they shall be of the two-winding type.
(c) When the operating apparatus of an existing electric freight elevator has a potential difference in excess of 250 volts, the hand control ropes or cables shall be provided with insulating balls, placed to prevent elevator operators from receiving electric shocks.
(d) An emergency stop switch shall be installed in every new electric elevator car when the hoisting machine is equipped with an electric brake. Such a switch shall operate to open a main line switch independent of the car-controlling circuit wiring. An emergency switch shall be installed in each existing electric elevator car when the hoisting machine is equipped with an electric brake and shall operate to open a main line switch independent of the car-controlling circuit wiring.
(e) In all installations where the power for elevator control switches 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 connected to such main line circuit breakers, potential switches or other similar electric apparatus, will not cut off the power to the elevator control circuit.
(f) The machine controllers of all electric freight elevators shall be equipped with a potential switch of either the manual 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.
(g) Switches shall be provided in connection with new electric freight elevators so that the motor control circuit and the brake control circuit are opened before or at the time the governor trips. Switches shall be provided in existing electric freight elevators so that the motor control circuit and the brake control circuit are opened before or at the time the governor trips or when the safety operates.
Cross References This section cited in 34 Pa. Code § 7.283 (relating to safety requirements); 34 Pa. Code § 7.291 (relating to general); and 34 Pa Code § 7.296 (relating to belted and silent chain drive elevators).
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