Planning safe egress starts with the right UL 924–listed signage: compliant illumination for power-loss events, clear direction at every decision point, and hardware suited to your interior and environment. This guide covers code essentials, mounting styles, face configurations, arrows, environmental ratings, durability, and maintenance planning—so your team can specify confidently and pass inspection the first time.
Last updated: October 2025
UL 924 Compliance & Code Basics
UL 924 certifies that egress legends meet visibility and reliability standards, including minimum letter geometry (commonly 6" tall with a 3/4" stroke), adequate contrast, and illumination performance in normal and emergency modes. Most jurisdictions incorporate UL 924 via NFPA 101 (Life Safety Code), IBC/IFC, and OSHA, which collectively require the legend to remain illuminated for at least 90 minutes during a power failure. Inspectors typically verify the listing mark and the 90-minute function on site.
Placement fundamentals come from NFPA 101/IBC: mark every final discharge door; provide intermediate markers so that from any point along the path, the route is unmistakable; and add directional indicators wherever the way forward is not obvious (turns, intersections, re-entry to stairs). Wire electric units to an unswitched or emergency branch that cannot be turned off during occupancy. When in doubt, request your AHJ’s interpretation early—local amendments (e.g., letter size, material, or color) can be stricter than the base code.
Illumination Types: Electrical vs Non-Electrical
Egress legends fall into two broad families, each code-compliant when installed per listing:
- Electrical (LED-illuminated): Hardwired luminaires with universal 120/277 VAC input and integral emergency circuitry. These are the workhorses for interiors: efficient LEDs, long life, and flexible form factors (classic thermoplastic housings, architectural edge-lit panels, and heavy-duty metal frames). Choose this class for most conditioned spaces and where maximum legibility and feature options are desired.
- Non-Electrical: Photoluminescent (phosphor materials “charge” under ambient light and glow when power fails) and tritium self-luminous (sealed tubes glow continuously for their rated lifespan). These eliminate wiring and battery maintenance, but photoluminescent models require sufficient charging light during occupancy and have defined viewing distances; tritium options have end-of-life disposal protocols and are restricted in some jurisdictions. Use non-electrical where wiring is impractical or as a sustainability choice in well-lit interiors.
Hybrid strategies are common: LED units in most locations, photoluminescent in specific retrofits, or tritium for remote structures with no power. Whatever you pick, confirm the product’s UL 924 listing and the rated viewing distance meet the plan.
Mounting Methods: Ceiling, Wall & End
Most luminaires ship with a universal canopy that supports top (ceiling) or side (end/flag) mounting, plus back-plate knockouts for wall installs. Pick the method that maximizes sightlines and minimizes obstructions:
- Wall (Back) Mount: Flush to a wall over doors or along corridors—ideal for single-face legends when traffic approaches from one side only.
- Ceiling (Top) Mount: Suspended below the ceiling plane for long sightlines in hallways and open spaces—typically paired with double-face legends.
- End (Flag) Mount: Projecting from a wall to cover perpendicular approaches—also typically double-face.
Designer notes: Recessed kits conceal hardware for a near-flush aesthetic (verify cavity depth and service access). Pendant accessories can lower the legend from tall ceilings in atria or warehouse bays. In all cases, set the canopy orientation before pulling conductors so the legend squares to the corridor and arrows will point correctly on the first try.
Face Configurations: Single vs Double
Single-face legends present one reading surface; double-face units read from both directions. Many SKUs are field-configurable (ship with two faces and a blank insert): use one face and a backplate for wall installs, or both faces for ceiling/flag mounts. This flexibility reduces ordering errors and change-orders. During install, ensure unused knockouts are sealed and any face retaining hardware is fully engaged—misaligned faces or light leaks are common punch-list items.
Directional Indicators (Chevrons)
When the egress route bends or branches, add a directional indicator on the legend to clarify the path. Most products use knockout chevrons or supplied decals; higher-end architectural panels may be ordered with a factory arrow orientation. Only display indicators that correspond to a real path—never leave a stray arrow illuminated. Before final tightening, stand back in each approach direction and confirm indicators match travel; cover or replace mistaken knockouts with the manufacturer’s blocker plates to avoid light bleed.
Environmental Listings: Indoor, Damp & Wet
Match the enclosure to conditions to preserve listings and uptime:
- Indoor / Dry: Standard units for conditioned spaces with no water exposure.
- Damp Location: Handles humidity or occasional condensation (covered entries, poolside interiors, kitchens). Many architectural panels carry this rating—verify on the spec sheet.
- Wet Location / Weatherproof: Gasketed housings and sealed entries for direct rain, wash-down, or driving moisture (exterior doors, open garages, food processing). Look for language like “Suitable for Wet Locations,” NEMA 4/4X, or IP65/66.
Special cases: Cold-weather packages maintain battery performance in freezers or winter climates; hazardous-location enclosures (Class I Div 1/2, etc.) are mandatory in classified areas. If you need outdoor or harsh-duty hardware, consider starting at the Weatherproof lineup or specifying metal housings for added resilience.
Legend Color: Red vs Green (AHJ Notes)
Both red and green legends are widely accepted in the U.S., provided contrast and geometry meet code. Some cities and occupancies prescribe one color (or letter height) explicitly—e.g., specific high-rise or transit applications. If your standard includes color or language requirements, set it in submittals and keep it consistent across the facility to avoid mixed signaling. When aesthetic integration matters, architectural and edge-lit families offer color-specific SKUs as well as field-selectable models; confirm the approach with your AHJ during plan review.
Durability & Tamper Resistance
Where abuse is likely—gyms, schools, transit hubs, loading docks—choose hardware with higher mechanical strength. Steel and die-cast aluminum housings resist impact better than basic thermoplastic and accept tamper-resistant fasteners or wire guards. If your spec or RFP mentions “vandal-resistant” performance, include a guard kit and note the mounting substrate (solid blocking beats hollow drywall). To browse heavy-duty options quickly, start with Steel-Housing Models or Die-Cast Frames for higher abuse resistance.
Backup Power & Self-Diagnostics
Electric luminaires incorporate a charger and battery pack to meet the 90-minute emergency requirement. A bi-color status LED indicates readiness and fault conditions. To simplify code upkeep, consider units with self-diagnostic testing that automatically perform the monthly quick test and annual 90-minute discharge, then log or signal results. This reduces manual rounds and speeds troubleshooting (e.g., battery end-of-life, LED string failure, charger faults). Facilities with many devices often standardize on self-diagnostics for consistency and inspection transparency.
Maintenance notes: After any outage or full discharge, expect typical recharge times of ~24 hours. Keep a simple test log (date, pass/fail) or adopt the manufacturer’s indicator code sheet so staff can verify status at a glance during monthly safety walks. For areas with frequent cycling or extreme temperatures, plan shorter battery replacement intervals and specify chemistry accordingly.
AHJ Planning Checklist
- Listings: UL 924 on every unit; spec sheets attached to the submittal set.
- Geometry & contrast: Letter height/stroke and legend color match AHJ requirements.
- Location & quantity: All discharge doors, turns, and intersections clearly marked; sightlines validated with a walk-through.
- Indicators: Only true chevrons displayed; no stray arrows or light leaks.
- Mounting: Face count fits the approach; canopy orientation set before wiring; mechanical fasteners secure.
- Environment: Indoor/damp/wet/hazardous listing matches each space (no dry-rated outdoors).
- Power & runtime: Unswitched/emergency branch supplied; push-to-test or self-test confirms 90-minute performance; recharge verified.
- Maintenance: Testing schedule established; self-diagnostic indicator legend posted; logbook created.
Resources
FAQ
What does UL 924 actually test?
It covers construction and performance for life-safety egress luminaires: legend geometry and visibility, electrical safety, emergency operation (including the 90-minute requirement), and markings.
Do I need battery power on every unit?
Most electric models include an internal pack to meet the 90-minute rule. Non-electrical photoluminescent and tritium variants meet the rule differently (stored light or self-luminous), and generator-backed systems are acceptable where installed and maintained per code.
How do I choose red vs green legend color?
Follow local preferences or mandates and stay consistent within the occupancy. Both colors pass when contrast and geometry meet code.
When should I specify metal housings?
In high-abuse zones or where long lifecycle and serviceability matter. Steel and die-cast frames resist impacts and accept tamper-resistant accessories.
What’s the most common field error?
Incorrect or missing directional indicators after a corridor turn, followed by using dry-rated hardware outdoors. A quick pre-punch list walk-through catches both.