This buyer’s guide compares the best battery-backup exit signs for 2025 by building type—schools, warehouses, hospitals, cold storage, wet locations, and hazardous locations. It explains how backup systems work, the certifications to require, and how to stay inspection-ready under UL 924 and NFPA 101.
Last updated: August 2025
Quick Picks
Schools
- Pick: Self-testing LED exit sign or combo; vandal-resistant where abuse is likely.
- Why: High traffic & impacts; minimize manual testing time.
- Require: UL 924, NFPA 101 runtime; optional wire guard or “swinging” mount.
Warehouses & Wet
- Pick: High-lumen exit/emergency combo; NEMA 4X/IP66 where wet or dirty.
- Why: Big spaces need light coverage; durability vs. dust, spray, vibration.
- Require: UL 924; damp/wet listing; dual-voltage (120/277 VAC).
Hospitals & HazLoc
- Hospitals: Architectural edge-lit with self-diagnostics; quiet, low-profile.
- Hazardous: Class I Div 2 (or Div 1 if needed) explosion-proof exit signs.
- Require: UL 924; JCAHO testing cadence; UL 844 for haz-loc.
Battery-Backup Basics (How They Work)
Battery-backup exit signs are AC-powered LED signs with an internal charger and battery pack that automatically switches to emergency mode during a power loss. To comply with UL 924 and NFPA 101, they must provide a minimum of 90 minutes of illumination during an outage. Modern units use efficient LEDs, smart chargers, and self-diagnostic controllers to reduce maintenance.
Key components
- LED legend: Red or green letters; 6" letter height is standard for visibility.
- Battery pack: Common chemistries include Ni-Cd (rugged, proven), NiMH, and LiFePO4 (long life, low maintenance).
- Charger & controller: Manages charge, brownout protection, low-voltage disconnect, and optional self-testing.
- Test interface: Push-to-test button and status LED; some models log automatic monthly/annual tests.
Battery chemistries (quick view)
- Ni-Cd: Wide temp tolerance, reliable 90-min discharge, 3–5+ year typical life.
- LiFePO4: Longer life (often 8–10 yrs), light weight, low self-discharge; may need heaters for deep cold.
- Lead-calcium/NiMH (select units): Niche or high-capacity uses (e.g., remote-head loads).
Compliance Snapshot: UL 924, NFPA 101, OSHA
- UL 924: Performance standard for emergency lighting/exit signs (90-minute runtime, visibility, recharge, diagnostics where provided).
- NFPA 101 (Life Safety Code): Requires monthly 30-second functional tests and annual 90-minute full-duration tests; signage must be readily visible along the egress route.
- OSHA: Exit routes must be marked and illuminated at all times; signage must not be obstructed.
- Special jurisdictions: NYC/Chicago may require specific letter sizes, legends (e.g., “STAIR”), or construction (metal housings). Verify locally.
Best Picks by Building Type
Schools
What to buy: LED exit sign or exit/emergency combo with self-diagnostics to reduce manual testing. Use vandal-resistant housings (steel or polycarbonate lens) or a swing-mount bracket in gyms and hallways prone to impact.
- Require: UL 924, NFPA 101 runtime; dual-voltage (120/277 VAC).
- Nice-to-have: Universal mount (ceiling/end/wall), field-selectable chevrons, wire guard options.
- Common mistakes: Using fragile thermoplastic near courts; skipping arrow direction planning; no logs for tests.
Warehouses
What to buy: High-lumen exit/emergency combos for wide light coverage at doors and cross-aisles. Use NEMA 4X/IP66 units if exposed to dust, washdown, or weather. Add wire guards in forklift lanes.
- Require: UL 924; damp/wet listing where applicable; dual-voltage input.
- Nice-to-have: Remote-capable battery for additional remote heads; heavy-duty housings.
- Common mistakes: Undersized lamp heads in tall spaces; no sealing in dusty bays; blocked sightlines by racks.
Hospitals
What to buy: Architectural/edge-lit LED exit signs with self-testing for corridors and public areas; compact combos in stairwells and non-generator-backed spaces. Quiet, low-profile designs help in patient zones.
- Require: UL 924; NFPA 101/JCAHO testing cadence; damp location listing.
- Nice-to-have: Recessed kits, field-selectable red/green, long-life LiFePO4 batteries.
- Common mistakes: Inconsistent letter colors; poorly placed signs at complex corridor junctions; no documented test logs.
Cold Storage
What to buy: Cold-weather rated exit signs or combos with internal battery heaters (to –4°F, –20°F, or –40°F, as needed). Prefer NEMA 4X/IP66 enclosures with gasketed lenses; LED heads aimable for aisle coverage.
- Require: UL 924 at the lowest ambient; sealed, insulated enclosure; verify minimum temp rating on spec sheet.
- Nice-to-have: Remote-capable batteries located outside the freezer; conduit entries with sealed glands.
- Common mistakes: Installing standard units in freezers; not testing at actual cold temps; unsealed penetrations causing frost/condensation.
Wet Locations (Outdoors, Wash-Down)
What to buy: NEMA 4X/IP66 LED exit signs or combos with corrosion-resistant hardware (stainless screws, UV-stable lens). For parking decks, docks, canopies, or food processing, these keep water, spray, and dirt out.
- Require: UL 924; Wet Location listing; gasketed lens; UV-stable materials.
- Nice-to-have: NSF options for food facilities; top/end/wall mount canopy; tamper-resistant fasteners.
- Common mistakes: Using damp-only fixtures outdoors; missing conduit seals; faded legends from sun exposure.
Hazardous Locations
What to buy: Exit signs certified for Class I/II (Div 1 or 2) as required—often explosion-proof housings (cast aluminum, flame-path joints) and sealed electronics. In less severe Div 2 areas, compact haz-loc rated LED signs may suffice.
- Require: UL 924 and UL 844; correct Class/Division/Group match; NEMA 4X where weather-exposed.
- Nice-to-have: Self-diagnostics; external sealed test button; pendant/ceiling kits per hazardous wiring methods.
- Common mistakes: Installing non-rated signs in haz-loc areas; mixing non-approved parts; loose covers breaking flame-path integrity.
Testing & Maintenance (Logs Included)
Required cadence
- Monthly: 30-second functional test (manual push-button or automatic self-test).
- Annually: 90-minute full-duration discharge test (verify readable brightness at end).
- Always: Keep a written log of dates, results, and corrective actions.
Pro tips
- Standardize on self-testing models to reduce lift time and after-hours testing labor.
- Stage battery replacements by area (e.g., one wing/quarter) to avoid scattered failures.
- In freezers, perform tests at actual cold conditions to confirm heater and pack performance.
- Use wire guards and secure anchors in gyms/warehouses to prevent impact damage.
Comparison Tables & Buying Checklist
Battery chemistry vs. environment
| Chemistry | Pros | Watch-outs | Great for |
|---|---|---|---|
| Ni-Cd | Rugged, cold-tolerant, proven 90-min | Periodic replacement (3–5+ yrs) | Schools, warehouses, wet/cold with heaters |
| LiFePO4 | Long life, low maintenance, light weight | Heater may be needed in deep cold | Hospitals, offices, general commercial |
| Lead-calcium / NiMH | High capacity for remote heads | Heavier, niche applications | Large warehouses, remote-head networks |
Housing & enclosure selection
| Housing | Strengths | Use cases |
|---|---|---|
| Thermoplastic | Budget-friendly, light, easy install | General interiors; add guards where abuse likely |
| Steel/Die-cast | Vandal-resistant, durable | Schools, warehouses, public exteriors |
| NEMA 4X/IP66 | Sealed, corrosion-resistant, washable | Wet, outdoor, food processing, cold storage |
| Explosion-proof (UL 844) | Flame-path containment, haz-loc safe | Class I/II Div 1/2 hazardous locations |
Buyer’s checklist
- Certifications: UL 924 (and UL 844 for haz-loc); damp/wet or NEMA 4X as needed.
- Runtime: 90 minutes minimum at your ambient (verify cold ratings).
- Diagnostics: Self-testing/monitoring; clear fault indicators.
- Power: Dual-voltage 120/277 VAC; remote-capable if feeding extra heads.
- Mounting: Universal canopy; ceiling/end/wall options; secure anchors.
- Service: Accessible battery/board; available replacement parts.
Checklists & Templates
Exit Sign Testing Log (CSV)
Columns: Location • Unit ID • Date • Monthly/Annual • Pass/Fail • Notes • Tech Initials.
Maintenance Schedule (CSV)
- Monthly 30-sec test (auto/manual)
- Annual 90-min discharge
- Battery age tracking & replacement plan
Visuals & Explainers
Frequently Asked Questions
How long do exit sign batteries last?
Most Ni-Cd packs last 3–5+ years; LiFePO4 can last longer. Replace sooner if the unit fails a 90-minute test.
Do self-testing signs satisfy NFPA 101 testing?
Yes—self-testing can automate the required monthly/annual checks. You still need to maintain and retain test records.
What does “remote-capable” mean?
The exit sign’s battery can power additional remote emergency lamp heads. Confirm total wattage vs. runtime math.
Red vs. green letters—does it matter?
Both are code-accepted; verify local preferences (e.g., healthcare design) and maintain consistency across a facility.
What’s the difference between Wet Location and NEMA 4X?
Wet Location means the unit is listed for water exposure; NEMA 4X adds dust-tight and corrosion resistance for harsher sites.
Can I use a standard sign in a freezer?
No—use a cold-weather rated model with a battery heater and a verified minimum operating temperature on the spec sheet.
Tools & Calls-to-Action
Remote-Head Load Calculator
Enter lamp wattage and count to size a remote-capable battery for 90-minute runtime.
Spec Review
Upload your environment and constraints (cold, wet, haz-loc) for a short-list of compliant models.
Talk to a Code Specialist
Get help mapping UL 924, NFPA 101 testing, and local AHJ expectations to your facility layout.