Photoluminescent Grades: PSPA Class A to D Comparison
For a full overview of legal requirements, see our core guide on Safety Sign Materials Explained: Complete Comparison Guide.
Photoluminescent (glow-in-the-dark) safety signs are a critical component of life safety systems. However, not all photoluminescent materials are created equal. In the UK, the performance of these materials is classified by the Photoluminescent Safety Products Association (PSPA).
Understanding the difference between Class A, B, C, and D is essential for specifying the right level of protection for your environment.
What is Photoluminescence?
Photoluminescent materials absorb energy from ambient light (natural or artificial) and store it. When the light source is removed (e.g., during a power failure), the stored energy is released as visible light. The efficiency of this process is measured by Luminance (how bright it is) and Decay Time (how long it stays visible).
The PSPA Classification System
The PSPA Standard 002 Part 2 specifies four main performance categories. Luminance is measured in millicandelas per square metre (mcd/m²) at specific intervals after the charging light is removed.
| PSPA Class | Luminance at 10 mins | Luminance at 60 mins | Typical Application |
|---|---|---|---|
| Class A | 23 mcd/m² | 3 mcd/m² | Basic indoor use, low-risk areas |
| Class B | 50 mcd/m² | 7 mcd/m² | Standard commercial buildings |
| Class C | 140 mcd/m² | 20 mcd/m² | Industry Minimum for Wayfinding |
| Class D | 260 mcd/m² | 35 mcd/m² | Marine, Offshore, and High-risk sites |
Class A & B: The "Entry Level" Grades
Classes A and B are the most common grades found in general retail and low-occupancy offices.
- Class A: The bare minimum. It provides a brief glow that is useful for locating equipment in a room you are already familiar with.
- Class B: Offers significantly better initial brightness. It is suitable for buildings with short evacuation routes and good natural light charging.
caution: While cost-effective, Class A and B may not meet the requirements of modern Fire Risk Assessments for complex or high-occupancy buildings.
Class C: The Professional Standard
In 2026, PSPA Class C is widely considered the industry benchmark for professional safety way-guidance systems (SWGS). It is many times brighter than Class A and has a much longer decay period.
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- Best for: Warehouses, schools, hospitals, and high-rise residential buildings.
- Why choose Class C?: It provides enough luminance to be seen through light smoke and remains visible for several hours, covering the entire duration of most emergency incidents.
Class D: Premium Life Safety
Class D represents the highest performance grade. It is the material of choice for environments where failure is not an option.
- Best for: Marine/Shipping (SOLAS compliance), Offshore oil and gas, underground rail networks, and luxury high-rise developments with complex evacuation strategies.
- Why choose Class D?: It reaches full charge faster and provides a "floodlight" effect in total darkness, offering the highest level of reassurance and clarity during an evacuation.
Factors Affecting Performance
A PSPA rating is a laboratory measurement, but real-world performance depends on:
- Charging Light Source: LED lights provide an excellent charge, whereas some energy-saving bulbs may take longer to charge the material to its full potential.
- Charging Time: Most materials require about 60 minutes of exposure to 100-200 lux to reach full charge.
- Cleanliness: Dust and grime on the sign surface significantly block light absorption and release. Regular cleaning is essential.
- Age: Modern photoluminescent pigments (Strontium Aluminate) are extremely durable, but signs should still be checked during bi-annual fire audits.
ISO 16069 and Choice of Material
If you are implementing a Safety Way Guidance System (SWGS) under ISO 16069, the standard recommends using higher-performance materials (Class C or D) for low-location lighting (LLL) strips and exit markers. This ensures a continuous "path of light" that residents can follow even if they are crawling beneath smoke layers.
Conclusion
Choosing the right PSPA grade is a balance of risk and budget. While Class A may satisfy a basic checklist, Class C or D provides the performance required for true peace of mind and compliance with the most rigorous 2026 safety standards.
For most UK professional environments, we recommend PSPA Class C as the ideal middle ground for fire safety and wayfinding compliance.
Not sure which grade you need? Our team of specialists can help you determine the appropriate PSPA class for your project based on your Fire Risk Assessment.
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