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Specification 25: Photoluminescent exit signs

Specification 25 outlines the requirements for photoluminescent (PL) exit signs in buildings, detailing their application, illumination standards, and compliance with AS/NZS 2293.1. These passive safety devices enhance evacuation visibility by providing reliable, low-energy illumination during emergencies, complementing traditional emergency lighting systems while supporting sustainable building practices.

Specification 25 in the NCC Volume One provides detailed requirements for the use of photoluminescent exit signs in buildings. These signs are an alternative to traditional electrically illuminated exit signs and are designed to provide visibility in emergency situations, even during power failures.

The specification ensures that photoluminescent exit signs perform reliably and meet the safety standards required for use in compliance with AS/NZS 2293.3 and other referenced standards.

See also: Dual purpose Exit Signs in Buildings

Key elements of Specification 25

Compliance Requirements

Photoluminescent exit signs must comply with the following conditions:

  • Illumination Requirements: They must be exposed to a minimum of 100 lux of illumination from a light source with a colour temperature of at least 4000 K to charge the photoluminescent material effectively.
    Luminance Performance: In the event of power failure, the sign must maintain a luminance of at least 30 millicandelas per square meter (mcd/m²) for a duration of 90 minutes.

These performance metrics are critical to ensuring visibility for occupants during an emergency evacuation.

Testing and Certification

Photoluminescent signs must undergo rigorous testing to demonstrate compliance with:

  • Luminance decay standards: This ensures the sign maintains adequate brightness during the required emergency period.
  • Durability and Environmental Suitability: The signs should function effectively under the environmental conditions of the building where they are installed.

A test report or certification from an Accredited Testing Laboratory is typically required as evidence of suitability under A5G3 of the NCC.

Installation Guidelines

The placement of photoluminescent exit signs must meet specific criteria:

  • They should be located in areas where sufficient charging light is available to activate the photoluminescent material.
  • The signs must be installed in compliance with the general provisions of AS/NZS 2293.1 for exit signage, ensuring appropriate positioning, size, and directional guidance.

Key Advantages

Photoluminescent exit signs offer several benefits, including:

  • No Power Dependency: They do not rely on electrical power during operation (although they require to be in a continuously charged state by a minimum illumination of 100 lux at the face of the sign by a dedicated light source with a colour temperature not less than 4000 K ). This may lead to reduced energy costs.
  • Low Maintenance: These signs have fewer components that can fail compared to traditional illuminated signs.
  • Reduced Energy Consumption: Photoluminescent exit signs may offer reduced energy consumption when compared to a traditional exit sign.

Limitations

  • Photoluminescent signs are dependent on adequate exposure to charging light and may not perform effectively in poorly illuminated areas.
  • Specific maintenance practices are required to ensure the charging light sources remain operational and meet the required lux levels.
  • Contrast: Proper contrast ensures that the sign remains effective (visible) across a wide range of environments and visibility conditions, particularly in high-stress evacuation scenarios. Without sufficient contrast, even a fully compliant photoluminescent sign may fail to deliver its intended safety benefits.

Specification 25 ensures that photoluminescent exit signs meet stringent safety requirements, making them an option for emergency egress systems in certain building applications.

By adhering to the requirements of Specification 25 and AS/NZS 2293.1, building owners and designers can ensure compliance with the NCC while enhancing sustainability and safety.

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