19.110.030 General requirements.
(A) Shielding and Filtration.
(1) All outdoor light fixtures, except those exempt from this chapter and those regulated by Section 19.110.040, shall be fully or partially shielded as required in subsection (B) of this section.
(2) It is recommended that existing mercury vapor fixtures either be replaced or be equipped with a filter whose transmission is less than ten (10) percent total emergent flux at wavelengths less than forty-four hundred (4,400) angstroms. “Total emergent flux” is defined as that between three thousand (3,000) and seven thousand (7,000) angstrom units.
(3) Low pressure sodium lamps are the preferred lamp for minimizing adverse effects on astronomical observations.
(B) Requirements for Shielding. The requirements for shielding light emissions from outdoor light fixtures and recommendations for filtration are as set forth in the following table:
Fixture lamp type | Must be shielded | Filtering recommended |
|---|---|---|
Low pressure sodium1 | Partially | None |
High pressure sodium | Fully | None |
Metal halide5 | Fully | Yes |
Fluorescent | Fully4 | Yes2 |
Quartz3 | Fully | None |
Incandescent, greater than 150w | Fully | None |
Incandescent, 150w or less | None | None |
Mercury vapor | Fully6 | Yes6 |
Fossil fuel | None | None |
Glass tubes filled with neon, argon and krypton | None | None |
Other sources | As approved by the zoning director | |
Footnotes:
1This is the preferred light source to minimize undesirable light into the night sky affecting astronomical observations.
2Warm white and natural lamps are preferred to minimize detrimental effects.
3For the purposes of this chapter, quartz lamps shall not be considered an incandescent light source.
4Outdoor advertising signs of the type constructed of translucent materials and wholly illuminated from within do not require shielding.
5Metal halide lamps shall be in enclosed luminaires. See also Section 19.110.040(F).
6Recommended for existing fixtures. See also Section 19.110.040(D).
(Ord. No. 196, 4-25-84; Ord. No. 2009-08, §§ 1, 2, 6-2-09. 1976 Code § 15-1-73)