Wet-Location Emergency Lights Guide

What’s New in 2025 (Quick Hits)

• Improved gaskets & lands: wider sealing surfaces maintain compression through seasonal expansion.
• Electronics hardening: conformal coatings and potting defend against condensation.
• Smarter heat kits: LiFePO₄ + thermostatic heaters preserve 90-minute runtime in sub-freezing temps.
• Long-throw optics: tighter beams extend coverage for stairs, ramps, and walks with fewer fixtures.
• Sealed entries: more models include liquid-tight hubs and gland nuts for every penetration.

Wet vs Damp Ratings: The Difference

Damp-location units tolerate humidity/condensation in sheltered areas (canopies, locker rooms) but not direct water. Wet-location units are built for direct rain, snow, and hose spray. Using damp models in wet zones shortens life and risks failure; using wet-rated in damp zones is acceptable and safer for egress reliability.

Rule of thumb: If wind-driven rain or wash-down can reach the fixture, specify wet-location.

What Makes a Fixture “Wet-Rated”

Wet-location emergency lights must be UL 924 listed and explicitly marked “Suitable for Wet Locations.” Look for:

• NEMA 4 / 4X enclosures: hose-down safe; “4X” adds corrosion resistance for coastal/chemical sites.
• High IP ratings: IP65/IP66 indicate dust-tight with protection against water jets.
• Sealed interfaces: gasketed lenses/covers, O-ringed indicators/buttons, stainless hardware.
• Wide temp ranges: options for heaters or low-temp battery packs; UV-stable lenses for sun exposure.

NEMA/IP Ratings & Sealing

• Gasket design: continuous silicone/rubber gaskets with even compression; secure latches/screw patterns.
• Leak hot-spots: poorly sealed pilot lights, test ports, or conduit entries—spec fixtures that include seals for each opening.
• Install best practices: use liquid-tight connectors; tighten covers in a star pattern to OEM torque; re-check after 24 hours.
• Materials: UV-stabilized polycarbonate, powder-coated aluminum, fiberglass, or stainless; stainless fasteners to prevent rust tracks.

Pro tip: Near coast/chemicals, pick NEMA 4X and verify salt-spray / corrosion performance.

Cold-Weather Performance

• Heater kits: keep batteries in their optimal window to preserve 90-minute runtime during freezes.
• Battery chemistry: LiFePO₄ outperforms SLA/Ni-Cd in cold and lasts longer.
• Circuit loading: factor heater wattage when many units share a circuit.
• Real-world testing: perform the annual 90-minute test at winter temps.

Alternate strategy: place the power pack indoors and feed remote heads outside—keep batteries warm while lighting the exterior path.

Outdoor Mounting & Wiring

• Use rated fittings: rain-tight or liquid-tight connectors for every entry—don’t rely on bare conduit threads.
• Avoid water traps: use drip loops; prefer bottom/side entries where possible.
• Site placement: away from downspouts/roof edges; under overhangs when available.
• Surface prep: shim or use plates on rough masonry to maintain full gasket contact.
• Lock the aim: tighten head set-screws for wind/vibration; use wire guards where impacts occur.
• Extend coverage: pair a wet-rated host with wet-rated remote heads to reach alcoves/turns with fewer batteries.

Photometrics & Aiming

• Output & beams: choose flood for broad areas; narrow beams for throw distance; corridor optics for paths.
• Aim for egress: one head down the route, one to landings/doors/intersections; verify stairs/ramps.
• Night checks: walk with a meter; find and fix “dead zones” from rails, columns, parked cars.
• Meet code: target ≥1 fc avg and ≥0.1 fc min at floor per egress standards.
• Manage glare: angle heads to wash surfaces, not eyes; consider visors/shields if needed.

Spec Checklist

• Listings: UL 924 and “Suitable for Wet Locations.”
• Enclosure: NEMA 4/4X and/or IP65/IP66.
• Temperature: operating range covers site climate; add heaters for freezes.
• Runtime: ≥90 minutes at required illuminance; battery type and availability noted.
• Diagnostics: consider self-testing for faster inspections.
• Photometrics: lumen/beam match spacing and mounting height; high-output options where needed.
• Remote capacity: confirm watts/voltage for any external heads (wet-rated).
• Housing: UV-stable plastics or coated metals; vandal-resistant features as needed.
• Mounting: included plates/boxes; compatible with standard J-box where applicable.
• Indicators: visible charge/test access; remote test options for hard-to-reach installs.
• Local rules: check jurisdictional specifics (e.g., Chicago/NYC material or marking requirements).

Commissioning & Maintenance

• Initial test: charge 24+ hours, then run a full 90-minute discharge; verify aim/coverage.
• Re-torque & inspect: re-tighten covers; check for leaks after first storm; re-seal if needed.
• Label & log: note install/test dates; ID units for easy AHJ review.
• Ongoing: monthly quick tests, annual full tests, plus gasket/ingress checks and lens cleaning.
• Leverage self-test: indicator LEDs surface faults early—see our Self-Testing Guide.

Use-Case Scenarios

Outdoor Stairwell (Fully Exposed, Coastal)

Pick a NEMA 4X polycarbonate or fiberglass unit with stainless hardware; mount at top and mid-landing. Use liquid-tight entries and aim one head down treads, one to the egress landing. Night test confirms ≥1 fc on steps even in driving rain; corrosion resistance preserves seals in salty air.

Parking Garage Breezeway (Covered, Wind-Blown Rain)

Though “covered,” wind pushes rain inside—spec wet-location IP66 fixtures on side walls every ~30 ft. Add self-diagnostics for quick patrol checks and wire guards for carts/impacts. Result: compliant illumination in storms without compromising enclosure integrity.

FAQ

Do all emergency lights need wet-location ratings?

No. Only those exposed to water. All must be UL 924 listed; add “Wet Location” where conditions demand.

Are damp-rated lights OK under canopies?

Not if wind-driven rain or sprinklers can reach the fixture. In most outdoor air, wet-rated is the safe choice.

What does “UL 924 wet location listed” mean?

The unit meets UL 924 egress performance and is constructed/tested for wet environments—inspectors look for both.

How do I confirm NEMA/IP ratings?

Check the spec sheet/label. Many products list both (e.g., NEMA 4X, IP66).

Will these work in freezing temperatures?

Yes—spec low-temp operation or heater kits; verify in winter with a full-duration test.

Do wet-location units need special maintenance?

Same monthly/annual tests plus seal checks. Keep lenses/weep holes clear; watch for gasket wear.

What about outdoor exit signs/combos?

Use wet-location exit signs and wet-location combo units to match exterior doors and discharge paths.