Lighting Regulations in Casa Grande, Arizona: Preserving the Desert Night Sky and Historical Character

Introduction: Casa Grande's Unique Lighting Context

Casa Grande, Arizona has a rich historical tapestry that influences its approach to urban planning, including lighting regulations. Home to the Casa Grande Ruins National Monument dating back to around 1450 C.E., this area represents significant ancestral Sonoran Desert people (Hohokam) heritage. These ancient ruins are believed to have potentially served astronomical purposes, making clear night skies particularly meaningful to the area's cultural identity.

Founded in 1879 and named after these impressive ruins, Casa Grande has transformed from an agricultural hub into a growing city that balances rural charm with urban convenience. The city's commitment to preserving its historical character is evident in landmarks like the 1925 Southern Pacific Railroad Depot.

This blend of ancient astronomical significance and historical preservation forms the foundation for Casa Grande's approach to lighting regulations, which aim to minimize light pollution while ensuring safety and functionality.

Quick Reference Guide: Key Lighting Requirements

• Dark Sky Protection: Regulations focus on minimizing undesirable light rays into the night sky that affect astronomical observations
• Preferred Light Source: Low pressure sodium lighting is recommended, especially near residential areas
• Shielding Requirements: Most outdoor lighting must be fully or partially shielded
• Illumination Levels:
• Local and collector streets: Minimum 0.4 lumens
• Arterial streets: Minimum 0.7 lumens
• Searchlights: Generally prohibited for advertising; require council permission
• Mercury Vapor: Installation prohibited
• Recreational Lighting: Restricted after 11 p.m.
• Permit Requirements: Application required for most outdoor lighting installations

Outdoor Light Control Ordinance (Chapter 15.48)

Purpose and Scope

Casa Grande's outdoor lighting regulations are primarily codified in Chapter 15.48 of the city code. The ordinance explicitly aims to protect night sky visibility for astronomical observations while ensuring adequate lighting for safety and security purposes.

These regulations apply to most properties within city limits, though single-family residences are generally exempt unless they install lighting fixtures exceeding 150 watts.

Light Fixture Types and Requirements

The ordinance establishes specific requirements for different types of lighting:

• Low Pressure Sodium:
• Preferred light source to minimize impact on astronomical observations
• Requires partial shielding
• No filtering required
• High Pressure Sodium:
• Requires full shielding
• No filtering required
• Metal Halide:
• Requires full shielding
• Filtering required
• Cannot be used for security lighting after 11 p.m. unless fully shielded
• Must be in enclosed luminaries
• Mercury Vapor:
• Installation prohibited
• Existing fixtures recommended to have filtering
• Incandescent (greater than 150W):
• Requires full shielding
• No filtering required

Shielding Specifications

The ordinance defines two types of shielding:

• Fully Shielded: Fixtures must be constructed so light rays are projected below a horizontal plane running through the lowest point where light is emitted
• Partially Shielded: The bottom edge of the shield must be below the plane centerline of the light source, minimizing light above the horizontal

Street Lighting Standards

Illumination Requirements

Casa Grande has established specific standards for street lighting to ensure public safety while minimizing unnecessary light:

• Local and Collector Streets: Must maintain a minimum of 0.4 lumens at any point along the right-of-way
• Arterial Streets: Must maintain a minimum of 0.7 lumens
• Intersections: Each intersection must have at least one light standard

Installation Standards

Street lights are required on all developed streets and must be installed under the direction of the city engineer in accordance with city standard specifications.

Specific Use Lighting Requirements

Mobile Food Units

Mobile food units must provide adequate lighting for customer safety in vending areas. This lighting must be directed downward and away from rights-of-way and adjacent properties.

Parking Areas

Lighting for off-street parking areas must:

• Deflect light away from adjoining residential zones and public streets
• Comply with the city's Dark Sky Ordinance (Chapter 15.48)
• Utilize full cut-off fixtures
• Be designed to ensure adequate site security
• Be included in site plan reviews

Commercial and Industrial Areas

When commercial or industrial buildings are adjacent to residential properties or zones, low pressure sodium lighting should be predominantly used to minimize impact.

Prohibited Lighting Practices

Casa Grande prohibits several lighting practices to protect night sky visibility and prevent nuisance:

• Searchlights: Operation of searchlights for advertising purposes is prohibited without specific council permission
• Unshielded Outdoor Illumination: Prohibited except with incandescent fixtures less than 150 watts
• Excessive Light Trespass: Lighting that causes substantial and unnecessary interference with neighboring properties is prohibited
• Mercury Vapor Fixtures: Installation is prohibited

Recreational Facility Restrictions

No outdoor recreational facility, whether public or private, may be illuminated by nonconforming means after 11 p.m., except to conclude specific events in progress prior to that time.

What Property Owners Should Know

Permitting Requirements

Before installing outdoor lighting, property owners must:

1. Submit an application showing compliance with the lighting ordinance
2. Provide plans indicating the location and type of lighting fixtures
3. Include descriptions of illuminating devices, fixtures, lamps, and supports
4. Submit manufacturer catalog cuts and drawings when necessary

For lighting installations that are part of a building permit application, compliance with lighting regulations will be verified during the permit review process.

Exemptions and Special Considerations

The ordinance includes provisions for temporary exemptions (up to 30 days) and special exemptions in cases of extreme geographic or geometric conditions where conforming fixtures are not feasible.

Federal and state facilities are legally exempt from these requirements, though voluntary compliance is encouraged.

Supporting Casa Grande's Lighting Vision

As lighting professionals, Bock Lighting shares Casa Grande's commitment to preserving historical character while embracing appropriate modern technology. We understand the unique challenges of balancing safety and functionality with protecting the dark sky that makes astronomical observations possible—particularly important given Casa Grande's connection to ancient Hohokam astronomical sites.

Our Northeast Ohio manufacturing heritage dating back to 1918 gives us a deep appreciation for historical architecture and community character. We recognize the importance of Casa Grande's efforts to maintain its unique identity spanning from ancient ruins to railroad-era buildings to modern development.

Bock Lighting serves as an educational resource for communities navigating lighting regulations, helping property owners understand technical requirements like shielding, lumens, and appropriate light sources. Our experience with dark sky-compliant lighting helps communities like Casa Grande preserve their connection to the night sky while meeting contemporary needs.

We're committed to supporting Casa Grande's vision of responsible lighting that respects both its ancient astronomical heritage and its modern development needs.

Conclusion

Casa Grande's lighting regulations reflect its unique identity as a community with deep historical roots and astronomical significance. By balancing safety and functionality with dark sky preservation, these regulations help maintain the city's character while protecting important cultural resources.

Property owners should familiarize themselves with the shielding, filtering, and permit requirements before installing outdoor lighting. With careful planning, lighting can enhance safety, security, and aesthetics while respecting Casa Grande's commitment to preserving its historical character and night sky visibility.