Building or area lighting for any business, commercial, industrial or other nonresidential private use shall be so arranged as to direct the light away from any street and from any premises residentially used or zoned. Such exterior lights shall be mounted and shielded, such that light sources and lenses shall not be visible from any residential district. Luminaries shall be cut off (controlled) type, with the mounting height not to exceed 20 feet. Light overspill shall not create shadowing discernible without instruments on any residentially zoned premises. (NOTE: Sodium-vapor lighting is prohibited by Chapter 119 of the Code.)