Explosion-proof EXIT signs and emergency lights protect people in classified areas—so keeping them maintained isn’t optional. This guide gives facility teams and electrical contractors a practical, field-ready maintenance plan: what to check monthly and annually, how to care for batteries and gaskets, how to keep flame paths clean and fasteners torqued, and which records AHJs typically request.
Use this as an explosion proof light safety checklist—fast monthly confirmations plus documented annual runtime testing—so small issues don’t become failed inspections or unsafe egress conditions.
Safety First in Classified Areas
- Lockout/Tagout: Follow LOTO and site permits. Confirm area is safe or follow hot‑work procedures as required.
- No sparks/debris: Keep flame‑path surfaces clean; never grind/sand mating surfaces.
- Nameplate match: Verify Class/Division/Group and T‑code match the zone you’re servicing.
- Torque control: Use a calibrated torque wrench; tighten cover bolts in a cross pattern to ensure even gasket compression.
Before opening any enclosure: stage OEM replacement parts and a lint‑free wipe, and keep threads and mating surfaces free of paint, grit, or debris. If conditions aren’t safe, stop and follow site procedures.
Code context: Hazardous-Location Code Checklist
Maintenance Schedule (Monthly / Quarterly / Annual)
- Monthly (30s): Push‑to‑test or controller trigger; confirm transfer, head operation, and status LEDs. Visual: gaskets, corrosion, lens cleanliness, labels legible.
- Quarterly: Verify hardware torque, conduit sealing fittings, and labels. Wipe dust/film from lenses; check charging indicators; confirm EXIT legend visibility.
- Annual (90m): Full discharge test; verify required illumination for the entire duration; re‑aim heads if needed; record results and corrective actions.
- After service events: Re‑inspect flame‑paths and re‑torque bolts following any enclosure opening or vibration exposure.
Battery & Electronics Care
- Battery type: Follow OEM guidance (e.g., Ni‑Cd or LiFePO4). Replace like‑for‑like chemistry/capacity and verify temperature rating.
- Runtime health: If 90‑minute tests sag early, schedule replacement; don’t defer in hazardous areas.
- Charging: After swaps, allow initial charge time per OEM before running a full discharge test.
- Self‑diagnostics: Enable where available to log faults (battery/LED/charger) and reduce manual checks.
- Labeling: Mark install date and “replace‑by” date on the pack; log in CMMS with asset ID, Class/Div/Group, and T‑code.
Related: T‑Codes & Ambient Limits
Enclosure, Gaskets & Flame-Path Care
- Gaskets: Inspect for cracks/flattening; replace with OEM parts only. Clean and seat before re‑torque; avoid silicone or unapproved lubricants.
- Flame‑paths: Keep mating surfaces pristine; remove debris; torque cover bolts to spec—no over‑torque.
- Sealing fittings: Verify compound integrity and placement distance per NEC; never substitute ordinary fittings.
- Hinges/latches: Use OEM‑approved lubricant if required; ensure uniform compression around the enclosure.
Install reference: Installing Explosion‑Proof Lighting
Optics, Aiming & Egress Illumination
- Lens cleaning: Remove dust/film that reduces output; avoid chemicals that haze polycarbonate.
- Aiming: Re‑aim adjustable heads after changes (new equipment, ductwork) to keep doors, stairs, and turns lit.
- Combos + fills: Use combo units at doors; add separate hazardous‑location emergency lights to meet floor levels in wide/high‑bay areas.
- 90‑minute verification: Confirm foot‑candles at the start and end of the annual test; document re‑aiming.
Corrosion, NEMA/IP & Environment
- NEMA/IP: In washdown/salt spray, confirm NEMA 4X or IP66+ enclosures in addition to UL 844 hazardous rating.
- Finish: Touch‑up compromised coatings; consider marine‑grade options and 316 stainless hardware where applicable.
- Ambient swings: Where ambient is low/high, specify heaters or shields; check that T‑code applies at the site’s Ta.
Compare terms: Explosion‑Proof vs Wet‑Location vs Outdoor
Logs, Self-Diagnostics & AHJ Documentation
- Test log: Maintain monthly 30‑second and annual 90‑minute records; include corrective actions.
- Cut sheets & photos: Keep UL 844 + UL 924 cut sheets and nameplate photos (Class/Div/Group, T‑code, Ta) in the packet.
- Status indicators: Capture self‑test codes/events in your CMMS for audit trail and trend analysis.
- Commissioning packet: Store as‑builts, circuit IDs, torque values, and seal locations for inspector review.
Make it easy to audit: keep one-page device records (last 30‑sec test, last 90‑min test, corrective actions, current nameplate photo) so inspectors can review quickly.
Inspection prep: What Inspectors Check
Common Failures & Quick Fixes
- Passes 30s but fails 90m: Battery capacity degraded → replace with OEM‑spec pack; verify charger output.
- Condensation/corrosion: Check NEMA/IP fit, gasket condition, and sealing fittings; clean flame‑paths and re‑torque.
- Uneven/dim egress: Clean lenses, re‑aim heads, add hazardous‑location lights where needed.
- Frequent nuisance faults: Inspect charging circuit; verify ambient vs. T‑code limits; confirm conductor terminations.
Printable Maintenance Checklist
- Monthly 30‑sec test completed & logged
- Annual 90‑min test completed & logged
- Lens cleaned; heads re‑aimed as needed
- Gaskets intact; bolts re‑torqued to spec; flame‑paths clean
- Sealing fittings inspected; no ordinary fittings in classified runs
- Battery/charger healthy; self‑diagnostics enabled (if equipped)
- CMMS updated; cut sheets & nameplate photos on file
This guide is informational and not a substitute for professional engineering judgment or the authority of your AHJ.