All stairways and corridors in every building or structure in which theatricals, shows or amusements are offered, operated, presented or exhibited for gain, shall be supplied with a supplemental lighting system of electricity, gas or sperm oil, and the system shall be independent of all other lights in the building or structure and shall be in operation during the entire period that the building or structure is open to the public and until the entire audience has left the building. The word “Exit” shall appear in letters at least six inches high over the opening of every means of egress from the building or structure, and a red light shall be kept burning over the sign at all times at which the building is open to the public. No exit door or gates shall be locked or fastened in any manner during the entire time that the building or structure is open to the public. All aisles, passageways, corridors and exits of the buildings or structures shall be kept free from obstructions of any kind during any time the building or structure is open to the public.
(1959 Code, § 4-5)