This long-form resource explains what UL 924 is, how it’s tested, and what building owners must do to keep emergency lights and exit signs compliant. Written in plain English for facility managers, safety teams, and specifiers—so you can design, purchase, install, and maintain life-safety lighting with confidence. For related product categories, see battery backup exit signs and self-testing exit signs.
Last updated: August 2025
Quick Picks
What UL 924 Covers
- Legibility & luminance: Exit signs readable at 100 ft in darkness.
- Automatic switchover: Transfers to battery on power loss.
- Endurance: Lights/signs run for 90 minutes minimum.
Required Tests
- Monthly: 30-second functional “push-to-test.”
- Annual: Full 90-minute discharge.
- Tip: Self-testing units cut labor and missed checks.
Keep Clean Records
- Log date, tester, result, fixes.
- Retain for audits and AHJ inspections.
- Maps & QR IDs speed site rounds.
When Non-Electrical Works
- Photoluminescent: No wiring; needs charging light.
- Tritium: Always glows; plan end-of-life recycling.
- Photoluminescent Exit Signs · Tritium Exit Signs
Overview: What is UL 924?
UL 924 is the safety benchmark for emergency egress lighting in North America. It applies to hardwired emergency lights, LED exit signs, combination units, transfer devices/inverters, and qualifying non-electrical signs. The listing verifies how bright signs are at distance, how fast fixtures switch to backup power, and how long they keep running during an outage. It also evaluates enclosure materials and labeling, then backs that with ongoing factory surveillance. For project teams, specifying UL 924 reduces RFIs and inspection friction because it aligns with NFPA 101, IBC/IFC, and NEC Articles 700/701.
Shop UL 924 Listed Products
Use these collections to jump into compliant SKUs. Each category includes options with self-testing, high-output heads, remote-capacity, and accessories for differing environments (damp/wet/hazardous):
- Electrical Exit Signs
- Non-Electrical Exit Signs
- Emergency Exit Sign Combos
- Tritium (Self-Luminous) Exit Signs
UL 924 Testing Standards & Requirements
UL 924 validates exit sign legibility at up to 100 ft in darkness, requires standard letter geometry (6″ high, 3/4″ stroke, red or green), and proves automatic transfer to emergency power without human intervention. Emergency light units are evaluated for initial and sustained illuminance along egress paths as batteries discharge. Transfer devices and inverters must supply stable power to connected loads. Chargers, indicators, and test interfaces are examined for reliability, and labels/specs are audited to ensure what’s printed matches what’s shipped.
Because UL 924 ties directly to NFPA/IBC/IFC, listed products generally satisfy the life-safety portion of plan review. You’ll still size battery capacity and fixture count per your photometrics, but the product itself is pre-vetted to perform in an outage.
What Does UL Listing Really Mean?
A UL 924 mark is independent proof that a model reaches specified brightness at distance, switches correctly to battery, and runs long enough to evacuate. The program is not “one-and-done”—UL performs follow-up factory audits to ensure production stays identical to the sample tested. Because the listing aligns to NFPA 101, NEC 700/701, and model codes (IBC/IFC), AHJs recognize it as a reliable indicator of suitability. Practically, that cuts down on submittal back-and-forth and accelerates inspections.
90-Minute Emergency Runtime Requirement
Every UL 924 device must remain illuminated for at least 90 minutes after power loss—exit signs, emergency lights, and any remote heads connected to a central pack/inverter. Manufacturers usually build margin above 90 minutes to offset battery aging and temperature swings. For large corridors and stair towers, consider remote-capacity units that power additional heads—the total connected load still must meet the full 90-minute duration. Document load math in your submittals; re-check if scope changes add fixtures after design.
UL 94 Flammability Compliance
UL 94 ratings (e.g., V-0, V-1, 5VB, 5VA) classify the flame behavior of plastics used in enclosures. Tougher ratings mean faster self-extinguish, fewer flaming drips, and greater resistance to burn-through. In practice, that preserves the sign face and lamp alignment longer under heat, keeping messages visible longer in a fire. For harsher environments—or if your spec book prefers—select metal housings (steel/aluminum) or enclosures with higher UL 94 classifications.
Required Testing for UL Emergency Lighting
Monthly test (≈30s): Use the push-to-test (or circuit test) to force battery mode and confirm indicators show “pass.” This catches wiring mistakes, exhausted batteries, or failed boards early. Annual test (90 min): Simulate a full outage and verify every unit holds illumination for the entire period—note dimming, flicker, or failures and replace batteries/hardware as needed.
To reduce manual rounds, specify self-testing units with visual codes—or networked reporting for campuses and hospitals. These automate required checks, generate logs for inspectors, and cut truck rolls while improving compliance consistency.
Recordkeeping for Compliance
AHJs don’t just ask “Did you test?”—they ask “Prove it.” Maintain a simple, durable log with unit location/ID, date/time, test type (monthly vs annual), result, and corrective action. Keep records for the required retention period and align testing with other safety rounds (sprinklers/extinguishers). Color-coded plans and QR tags speed audits and help teams spot patterns like repeat failures on the same circuit.
Indoor Emergency Light Options
UL 924 covers multiple form factors. For offices/retail, thermoplastic units are cost-effective and low-profile: long-life LEDs, quick installs, easy spares. Tougher areas (warehouses, public corridors) benefit from steel/aluminum emergency lights that resist impact and heat—pair with guards where abuse is likely. Design-sensitive spaces (lobbies, hospitality, museums) often use recessed/architectural models that keep ceilings clean yet deliver compliant illumination when power fails.
Non-Electrical UL 924 Exit Signs
Photoluminescent exit signs store ambient light and glow in the dark—great for retrofits and energy targets. Confirm the space delivers sufficient charging illumination during occupancy and select a viewing-distance rating (50/75/100/125 ft) appropriate to corridors and atria. Tritium (self-luminous) exit signs glow continuously for 10–20 years without power or charging, ideal where lighting is intermittent or power access is impractical; plan licensed recycling at end-of-life. Compare options here: Photoluminescent Exit Signs and Tritium Exit Signs.
UL Listed Emergency Light Models
Our catalog includes UL 924 listed emergency lights, exit signs, and exit light combo signs built to pass plan review and field inspection. Mix and match by location: thermoplastic indoors, wet-location at exit discharge doors, recessed/architectural for premium interiors, and hazardous-location models where required. Many lines offer self-test and remote-capacity to simplify maintenance and reduce fixture count.
Popular Types
- Thermoplastic: Affordable and reliable for offices, schools, retail.
- Wet location: Gasketed, sealed for rain, spray, wash-down.
- Architectural recessed: Clean ceilings in lobbies and hospitality.
Buying UL 924 Emergency Lighting with Confidence
Every UL 924 product we offer includes the essentials for fast, compliant installs: long-life LEDs, integral test features, clear documentation—and typically a 5-year warranty with integrated 90-minute battery backup and mounting hardware. If you’re navigating local amendments (e.g., damp/wet ingress ratings, hazardous classifications, city-specific specs), our team can map requirements to your plans and build a concise, inspection-ready bill of materials. Fewer change orders, smoother walkthroughs, safer egress from day one.