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From theaters to transit terminals, exit signs are crucial components of public safety infrastructure. Their job is simple but essential—guide people safely out of a building during emergencies. But behind this simplicity lies decades of innovation, code revisions, and design shifts.
Then: Incandescent and Basic
Older exit signs relied on incandescent bulbs illuminating a metal or plastic housing with the word “EXIT.” These signs had limitations:
- Single-bulb design prone to failure during fires
- Low visibility in dark, smoky environments
- No standard on color or letter size, leading to inconsistency
They were also energy inefficient—burning 40W+ per fixture continuously. With thousands of signs installed in large facilities, energy costs were significant.
Now: Efficient and Reliable
1. Battery Advancements
Modern LED exit signs come with internal NiCad or lithium batteries. These last longer, recharge quickly, and provide the required 90-minute backup during outages—meeting UL 924 requirements.
2. Better Illumination
Today’s lighting tech includes LED, photoluminescent, and tritium-based designs. Each option serves different applications:
- LED: Energy-efficient and bright; common in commercial buildings
- Photoluminescent: Glow-in-the-dark signs that recharge from ambient light
- Tritium: Self-luminous for 10–20 years with no external power
3. International Design Trends
Global codes now favor pictogram-based signs, such as the Running Man. ISO 7010 recommends green signs with arrows for directional clarity. The U.S. still uses red “EXIT” text, but bilingual or symbol-based signs are gaining traction in multilingual areas like airports and universities.
Why Green vs. Red?
In Europe and Asia, green exit signs represent safety and progression. Red, often linked with danger, is used for alarms or warnings. In the U.S., red is still widely accepted and compliant under UL standards. Some states, however, now accept or prefer green models for new builds.
What Hasn’t Changed
- All exit signs must function during power loss (minimum 90 minutes)
- They must be mounted clearly along paths of egress
- They must meet visibility and contrast standards
These requirements are part of most national codes including NFPA 101 and the IFC.
Timeline of Exit Sign Innovation
1920s: Painted “EXIT” signs
Basic signage without illumination; visible only under normal lighting.
1950s: Incandescent-lit exit signs
First standardized internally lit signs; inefficient and failure-prone.
1970s: Fire codes begin referencing signage
Jurisdictions begin requiring illuminated exit signage in egress pathways.
1975: NFPA 101 mandates signage
Codifies minimum standards for exit sign visibility, color, and placement.
1980s: Fluorescent signs replace incandescents
Improved energy efficiency and longer lifespan introduced.
1985: UL 924 introduced
Defines battery backup, brightness, and visibility standards for exit signs.
1991: UL 924 adopted into IBC
Becomes mandatory for all commercial exit signage in the U.S.
1996: UL 1598 adopted
Establishes safety requirements for luminaires including damp-rated exit signs.
2001: UL 844 updated
Specifies classification for exit signs used in explosive/hazardous locations.
2003: NEMA ingress protection guide
Introduces IP ratings for wet-location and outdoor-rated fixtures.
2007: ANSI Z535 signage format standards
Standardizes colors, icons, and layout for improved legibility.
2010s: ISO 7010 pictograms adopted globally
“Running Man” signs used internationally for multilingual clarity.
Today: OSHA 1910.37 mandates smart systems
Exit signs integrate with BMS and feature auto-testing to reduce inspection errors.
Conclusion: Safety Through Innovation
The evolution of exit signs reflects how design, technology, and regulation converge to keep people safe. Whether you choose LED, tritium, or photoluminescent solutions, modern signs offer unparalleled reliability.
Browse all UL 924-compliant exit signs or dig deeper in our Product Knowledge Blog.