All outdoor lighting systems installed in zone one or zone two on or after 30 days from the effective date of the ordinance codified herein shall be shielded from above in such a manner that the edge of the shield shall be level with or below the center of the light source so that any direct light emitted above the horizontal is minimized. All outdoor lighting fixtures installed in zone two on or after 90 days from the enactment of the ordinance codified herein shall be shielded in such a manner so that any direct light emitted above the horizontal is minimized. Light direction refractors shall be considered to be light sources. [Ord. 1613 § 2.1, 1973; Code 1970 § 12.32.020.]