(a) Height. Public space shall have a minimum height of seven feet six inches measured from finished floor to finished ceiling.
(b) Light and Ventilation.
(1) Public space shall be provided with artificial light.
(2) In public stairs, stairways and passageways, electric lighting shall be available at all times so as to afford safe passage for occupants and users. Such lighting shall conform to the following:
A. A sufficient number of fixtures shall be provided so that the distance between fixtures is not more than thirty feet and so that no wall is more than fifteen feet distant from a fixture.
B. Incandescent lighting shall be based on not less than one-fourth watt per square foot of floor area, except that each fixture shall have a lamp or lamps with a total of not less than twenty-five watts.
C. Fluorescent lighting shall be based on not less than one-tenth watt per square foot of floor area, except that each fixture shall have a lamp or lamps of a total of not less than fifteen watts.
D. Where under these formulas the calculated wattage does not correspond to that of a standard lamp, the next larger size shall be used.
(3) Public spaces shall be provided with either natural ventilation, conforming to the requirements for habitable space, or with mechanical ventilation.