(a) Except as provided in subdivision (b) of this section, in every building seventy-five feet or more in height, all floors shall be served by at least one elevator which shall be kept available for immediate use by the fire department during all hours of the night and day, including holidays, Saturdays and Sundays. There shall be available at all times a person competent to operate the elevator, except that no attendant shall be required for buildings between seventy-five feet and one hundred fifty feet in height having elevators with automatic or continuous pressure operation with keyed switches meeting the requirements of reference standard RS 18-1 so as to permit sole use of the elevators by the fire department.
(b) In high rise buildings classified in occupancy group A, B, C, D, E, F, G or H, in buildings classified in occupancy group E with a gross area of two hundred thousand square feet or more, in buildings classified in occupancy group J-1 or J-2, in existing high rise buildings classified in occupancy groups C, F, G and H, in existing buildings classified in occupancy group J-1 (except "residential hotels," as such term is defined by the commissioner pursuant to rules and regulations) and in existing office buildings one hundred feet or more in height the number of elevators that shall be kept available for immediate use by the fire department as provided for in subdivision (a) of this section, shall be as follows:
(1) Where a floor is serviced by three or less elevator cars, every car shall be kept available.
(2) Where a floor is serviced by more than three elevator cars, at least three elevator cars with a total rated load capacity of not less than six thousand pounds shall be kept available for every floor. Such cars shall include not more than two cars which service all floors and at least one other car in another bank servicing that floor. If the total load capacity of all cars servicing the floor is less than six thousand pounds, all such cars shall be kept available.
(3) Such elevators which have automatic or continuous pressure operation shall be controlled by keyed switches meeting the requirements of reference standard RS 18-1.
(4) In high rise buildings classified in occupancy group A, B, C, D, E, F, G or H, in low rise buildings classified in occupancy group E with a gross area of two hundred thousand square feet or more and in buildings classified in occupancy group J-1 or J-2, all other automatically operated cars shall have manual operation capability.
(c) Notwithstanding the retroactive provisions of section 27-994 of article two of this subchapter:
(1) Existing office buildings one hundred feet or more in height shall comply with the requirements of this section by September thirteenth, nineteen hundred eighty-one. Complete plans of the installation shall be filed with the commissioner by June thirteenth, nineteen hundred eighty. A permit shall be secured from the commissioner by September thirteenth, nineteen hundred eighty.
(2) Existing high-rise buildings classified in occupancy group C, F, G or H and existing buildings classified in occupancy group J-1 subject to the requirements of this section shall comply with the requirements of this section on or before April first, nineteen hundred eighty-seven.