Lighting Regulations in Coolidge, Arizona: Preserving Dark Skies in a Growing Desert Community

Introduction

Coolidge, Arizona, founded in 1925 and named after President Calvin Coolidge, has a rich history deeply connected to its geographic location in the fertile valley south of the Gila River. Home to the nationally significant Casa Grande Ruins National Monument, which was established as the nation's first archaeological reserve in 1892, Coolidge values both its historical heritage and its natural resources.

Among these natural resources is something increasingly rare in our modern world: dark, star-filled night skies. Coolidge's lighting regulations reflect the community's commitment to balancing growth and development with preservation of the area's astronomical viewing conditions, historical character, and desert environment.

Quick Reference Guide: Key Lighting Requirements

Most critical requirements for property owners:

• Shielding Requirements: Most outdoor lighting fixtures must be fully or partially shielded
• Mercury Vapor: Installation of mercury vapor fixtures is prohibited
• Outdoor Illumination: Unshielded outdoor illumination is prohibited except with incandescent fixtures less than 500 watts
• Searchlights: Operation of searchlights for advertising purposes is prohibited
• Late Night Lighting: Outdoor recreational facilities must not use non-conforming lighting after 11:00 p.m.
• Permits: Installation of outdoor lighting requires proper permitting through the Building Inspector

Understanding Coolidge's Lighting Philosophy

Why Dark Sky Protection Matters

Coolidge's lighting regulations (Chapter 151) explicitly state their purpose: to "restrict the permitted use of outdoor artificial illuminating devices emitting undesirable rays into the night sky which have a detrimental effect on astronomical observations."

The city's proximity to important astronomical observation sites, combined with the naturally dark desert skies, creates both an opportunity and responsibility to preserve this increasingly rare natural resource. The regulations strike a careful balance between:

• Providing necessary lighting for safety and utility
• Minimizing unnecessary light pollution
• Preserving dark sky conditions for astronomical activities
• Supporting the historical character of the community

Historical Context and Community Values

As a community that grew from mining and cotton industries to embrace more diverse economic opportunities, Coolidge understands the importance of thoughtful development. The city's approach to lighting reflects its commitment to progress that doesn't come at the expense of its unique character and natural resources.

The Casa Grande Ruins National Monument, a key historical landmark, also benefits from dark sky preservation, as visitors can experience the site in conditions more similar to its historical context.

Technical Requirements for Outdoor Lighting

Shielding and Filtering Requirements

Different types of lighting must meet specific shielding and filtering requirements:

Fully Shielded Requirements (light projected below horizontal plane):

• Fluorescent: Fully shielded and filtered
• High pressure sodium: Fully shielded, no filtering required
• Incandescent greater than 150W: Fully shielded, no filtering required
• Mercury vapor: Fully shielded and filtered (for existing fixtures only)
• Metal halide: Fully shielded and filtered
• Quartz: Fully shielded, no filtering required

Partially Shielded Requirements:

• Low pressure sodium: Partially shielded, no filtering required

No Shielding Requirements:

• Fossil fuel lighting
• Glass tubes filled with neon, argon, or krypton

Filtering Requirements

For fixtures requiring filtering, the regulations specify:

• Filtering Standard: Must be equipped with filters whose transmission is less than 5% total emergent flux at wavelengths less than 3,900 angstroms
• Mercury Vapor Recommendation: Existing mercury vapor fixtures should have filters with less than 10% total emergent flux at wavelengths less than 4,400 angstroms (or be replaced)
• Preferred Lighting Type: Low pressure sodium lamps are the preferred lamp type for minimizing adverse effects on astronomical observations

Key Restrictions and Prohibitions

Prohibited Lighting Types

The code clearly prohibits several lighting practices:

• Mercury Vapor Installation: Prohibited 90 days after ordinance adoption
• Searchlights for Advertising: Operation of searchlights for advertising purposes is prohibited
• Unshielded Illumination: Unshielded outdoor illumination of buildings, landscaping, or signs is prohibited (with exception for incandescent fixtures less than 500 watts)
• Non-conforming Recreation Lighting: Outdoor recreational facilities cannot use non-conforming lighting after 11:00 p.m. (except to conclude events in progress)

Special Use Case: Metal Halide

Metal halide lighting has specific restrictions:

• Security Lighting: Cannot be used for security lighting after 11:00 p.m. unless fully shielded
• Enclosure Requirement: Metal halide lamps must be in enclosed luminaries

Exemptions and Special Circumstances

Existing Fixtures

The code provides consideration for lighting fixtures that pre-date the regulations:

• Non-conforming Status: Outdoor light fixtures fully installed prior to adoption may remain "non-conforming" indefinitely
• Changes Trigger Compliance: Any change in use, replacement, structural alteration, or restoration after abandonment requires compliance with current regulations

Temporary Exemptions

Property owners may request temporary exemptions:

• Duration: 30 days, renewable at the City Manager's discretion
• Application Requirements: Must specify exemptions requested, type of lights, duration, lumens, wattage, location, previous exemptions, and physical size/shielding
• Review Process: Building Inspector must approve or reject within 5 days
• Appeal Option: Rejections may be appealed to City Manager or Board of Appeals

Special Exemptions

In rare cases, special exemptions may be granted:

• Criteria: Only for extreme geographic or geometric conditions where no conforming fixtures would suffice
• Authority: Building Inspector must make a written finding justifying the exemption

Public Safety Lighting Requirements

Certain situations require specific lighting for public safety:

• Construction and Excavation: Work sites must provide "sufficient light during night time to prevent injury to persons"
• City Franchise Operations: Companies with city franchises must provide adequate nighttime lighting when excavating or altering streets, sidewalks, or rights-of-way

Special Business Requirements

Sexually-oriented businesses have specific lighting standards:

• Minimum Illumination: 5 foot-candles measured at floor level
• Documentation Required: License applications must include diagrams showing overhead lighting fixtures
• Continuous Compliance: Licensees must maintain required illumination whenever patrons are present

The Permitting Process

Applying for Lighting Permits

The code establishes a clear process for lighting permits:

• New Construction: Building permit applications must include lighting compliance documentation
• Standalone Lighting Projects: Require separate applications to the Building Inspector
• Documentation Needed: Plans showing location and type of lighting devices, fixtures, supports, and detailed descriptions
• Compliance Verification: Building Inspector may request certified test reports from a recognized testing lab

Making Changes After Approval

If you need to modify your lighting after receiving a permit:

• Submission Requirement: All changes must be submitted to the Building Inspector
• Documentation: Must provide adequate information to demonstrate continued compliance
• Approval: Changes require approval before implementation

Supporting Coolidge's Lighting Vision

Bock Lighting, with roots dating back to 1918, understands the unique balance Coolidge strives to maintain between development and preservation. As a manufacturer with experience in communities with dark sky concerns, we appreciate Coolidge's thoughtful approach to outdoor lighting.

We share Coolidge's commitment to preserving natural resources like dark skies while ensuring communities have the lighting they need for safety and functionality. Our experience with regional architectural styles and lighting needs positions us to understand the specific requirements of desert communities like Coolidge.

For residents and businesses navigating Coolidge's lighting regulations, we can serve as an educational resource to help understand options that respect both community character and local regulations. Our commitment to sustainable and responsible lighting practices aligns with Coolidge's vision for preserving its astronomical viewing conditions and historical character.

Conclusion

Coolidge's lighting regulations reflect the community's values and unique position as a growing desert city with important historical landmarks and dark sky resources. By carefully balancing the need for lighting with the preservation of night skies, Coolidge demonstrates its commitment to thoughtful development.

Property owners and businesses play a crucial role in maintaining this balance by understanding and complying with these regulations. Through proper shielding, appropriate fixture selection, and respecting illumination limits, community members help preserve Coolidge's character for generations to come.

Whether you're building new construction, renovating existing property, or simply replacing outdoor fixtures, keeping these regulations in mind will help you contribute to Coolidge's vision of a well-lit but dark-sky-friendly community.