Do Exit Signs Need Battery Backup?

Exit signs play a critical role in helping people evacuate safely during emergencies. The common question from owners, electricians, and facility teams—“Do exit signs need battery backup?”—has a simple answer: Yes, in almost every case. National model codes require emergency exit signage to remain illuminated for 90 minutes after a power failure. For a deeper overview of configurations, mounting, arrows, and AHJ planning, see our Exit Signs 101 pillar guide.

Legal & Code Requirements (UL 924, IFC, NFPA 101, OSHA)

Here’s how the primary standards address battery backup and emergency illumination:

• UL 924: Establishes performance requirements for egress lighting equipment. UL 924–listed signs must illuminate within 10 seconds of power loss and stay lit for 90 minutes via internal batteries or a compliant emergency power source. If a sign is not UL 924 listed, it likely isn’t code compliant.
• NFPA 101 (Life Safety Code): Requires illuminated signs along the egress path and mandates 90-minute emergency illumination. Transfer to emergency power must occur automatically.
• IFC (International Fire Code): Aligns with UL/NFPA, requiring exit signage to be continuously visible and to remain illuminated for 1.5 hours without normal power.
• OSHA: 29 CFR 1910.37 requires exits to remain visible and illuminated during outages. While OSHA doesn’t name batteries specifically, it requires the performance (90-minute illumination)—internal battery packs are the most common way to achieve this.

Pro Tip: Look for the UL 924 label—it’s the fastest way to confirm compliance.

Need product options? Start at Exit Signs, or consider Self-Testing models to automate monthly/annual checks.

Where Battery Backup Is Not Required

Although internal battery backup is the norm, there are legitimate alternatives—each still must meet the same 90-minute performance and be properly listed:

• Self-Luminous Signs (Tritium): Tritium tubes glow continuously with no electricity or batteries. See Tritium Exit Signs.
• Photoluminescent Signs: “Glow-in-the-dark” signs charge under ambient light and glow during outages—no batteries or wiring. Explore Photoluminescent options.
• Central Emergency Power: If a sign is fed by a generator or inverter that reliably provides 90 minutes of backup, an internal battery is not required.

Note: These paths must still satisfy visibility, duration, and listing requirements. Always confirm with your AHJ before selecting a non-battery approach.

What Building Inspectors Look For

Expect your AHJ to verify both the listing and the emergency performance. Common checkpoints include:

• Function Test: Will the sign illuminate without building power?
• Listing & Markings: Is the fixture clearly labeled as UL 924 listed?
• Visibility & Condition: Is the legend unobstructed, legible, and the housing intact?
• Battery/Status: For battery units, is the charge/status indicator normal (or the self-test indicator green)?
• Duration Proof: Some inspectors ask for evidence of a successful 90-minute test.

Alert: Exit signage failures are a frequent inspection issue. Review the AHJ checklist in our pillar to avoid common mistakes.

Best Practices for Compliance & Maintenance

• Monthly: Press the test button (or confirm auto-test) for ~30 seconds on battery power; log the result.
• Annually: Run a 90-minute discharge; document pass/fail and any corrective actions.
• Keep a Log: Maintain simple records (location, date, pass/fail, notes) for audits and AHJ visits.
• Battery Lifecycle: Replace packs every 3–5 years, or sooner if a unit fails its test.
• Consider Self-Testing: Auto-diagnostic units reduce labor and surface faults proactively—browse Self-Testing Exit Signs.

Tip: Keep spare batteries and a printed test log in the maintenance room to speed inspections.

Final Thoughts

Battery-backed egress legends are a life-safety essential—and a code requirement in nearly all scenarios. Whether you’re retrofitting or building new, verify your devices are UL 924–listed and capable of 90-minute operation. If you’re not using a listed emergency model (or an approved alternative like photoluminescent, tritium, or central power), you’re likely out of compliance.

Next step: Start with Exit Signs, or learn how auto-test reduces maintenance in our self-testing benefits guide. For a full code overview, see the UL 924 Compliance Guide.