All rooms in which food or drink is stored or prepared, or in which utensils are washed, shall be provided with artificial light sources equivalent to at least 20 footcandles at a distance of 30 inches from the floor or working surfaces, as measured by a suitable light meter, and such artificial light sources shall be in use except when equivalent natural light is present. This requirement does not apply to dining rooms. (Ord. 5212 § 1 (Exh. C), 1999; 1957 code § 4.02.150.)