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Remote Heads in Hazardous Areas — When & How to Use Explained

Remote Heads in Hazardous Areas — When & How to Use

Remote heads extend emergency egress lighting into classified spaces while keeping batteries/electronics where it makes the most sense. This guide explains when to choose hazardous‑location remote heads, how to power them, what to know about voltage drop and wiring, and how to stay aligned with UL 844, UL 924, and your AHJ.

Last updated: October 2025

Hazardous Emergency Lights  Explosion‑Proof Combo Buyer’s Guide

Educational Guide UL 844 • UL 924 • NEC 500–516 For Facility Managers & Electrical Contractors

What Are Hazardous-Location Remote Heads?

Remote heads are lamp-only fixtures (no onboard battery) that connect to a remote-capable emergency power source. In hazardous areas, the head itself must be UL 844 listed for the exact Class/Division/Group and have a suitable T-code. They deliver light where you need it—stairs, doors, turns—while letting you place batteries/electronics in a more serviceable or safer location.

  • Polarity matters: Most LED remote heads are DC—maintain polarity and use OEM‑approved drivers/modules.
  • Minimize penetrations: Heads can reuse existing conduits while the power source sits outside the zone.

Background: Class/Division/Group Primer

When to Use Remote Heads (Scenarios)

  • Keep electronics out of the zone: Battery/charger in a non‑classified or Div 2 space; run circuits to Div 1 heads in the hot zone.
  • Long corridors and turns: Heads at bends, doors, and stair entries to remove shadows and meet foot‑candle targets.
  • High bays: Multiple heads at height for uniform coverage vs. relying on a single combo at a door.
  • Retrofits: Reuse existing conduit to add heads without opening new penetrations in classified walls/ceilings.

Powering Options (Inside vs Outside the Classified Area)

  • Remote‑capable unit outside the zone: The UL 924 battery/charger sits in ordinary/wet location; heads in the classified space are UL 844 rated. This minimizes service inside the zone.
  • Haz‑loc remote‑capable unit inside the zone: When the power source must live in the classified area, ensure the enclosure and electronics are UL 844 listed for the correct Class/Div/Group and ambient.
  • Central inverter: Large sites can use a UL 924 inverter to feed multiple haz‑loc head circuits—confirm overcurrent protection and conductor sizing for distance.

Install flow: Installing Explosion‑Proof Lighting

Electrical Planning: Voltage, Load, Wire Gauge & Distance

  • Voltage: Remote heads are commonly 12 VDC or 24 VDC. Higher voltage typically supports longer runs for the same gauge/drop target.
  • Total load: Sum the head wattage on a circuit; compare to the source’s remote capacity (W) and runtime at your ambient.
  • Voltage drop: Design for ≤ 5% drop. Increase conductor size, shorten runs, or split circuits to stay within target.
  • Wire gauge: Use listed conductors for classified runs; follow manufacturer distance tables for 18–10 AWG at 12/24 V.
  • Segmentation & labeling: Long wings perform better with multiple shorter branches. Label J‑boxes and head circuits for the AHJ.
  • Design margin: Leave ~20% capacity headroom to account for ambient, battery age, and future adds.

Code context: Hazardous‑Location Code Checklist

Enclosures, Ratings & T‑Codes

  • UL 844 marking: Head nameplates must show Class/Division/Group and T‑code (or °C limit for dust) aligned to atmosphere and ambient.
  • NEMA/IP: Where washdown/salt/corrosion exist, choose NEMA 4X/IP66 in addition to the hazardous‑location listing.
  • Ambient limits: Verify max/min ambient for LED heads and power source; specify cold‑weather kits or shields where required.
  • Ingress protection at entries: Use listed glands/hubs and sealing fittings at required distances; keep flame‑paths pristine.

Ratings primer: T‑Codes for Explosion‑Proof Fixtures

Placement & Photometrics

  • Doors & stairs: Aim heads to remove shadows at egress doors and stair treads; verify uniformity.
  • Turns & obstacles: Add heads at corners, around tanks, and near equipment that blocks throw.
  • High‑bay strategy: Use narrow‑beam heads for long throws; add fills to lift minimums; confirm levels for the full 90 minutes.

Installation Notes (Seals, Hubs, Torque)

  • Sealing fittings: Use listed explosion‑proof seals/compounds at correct spacing; no ordinary hubs in classified conduit.
  • Flame‑paths: Keep mating surfaces clean; torque fasteners per spec; never over‑torque covers; re‑check after service.
  • Documentation: Identify emergency circuits and remote head runs on drawings; include nameplate photos in the packet.

Inspection prep: What Inspectors Check

Maintenance & Testing

  • Monthly: 30‑second functional test; verify indicators; quick visual of heads, lenses, and conduit seals.
  • Annual: 90‑minute discharge at the power source; confirm foot‑candles for the full duration; re‑aim heads as needed.
  • Records: Maintain logs plus cut sheets and nameplate photos (UL 844 Class/Div/Group, T‑code, Ta).

Common Mistakes

  • Using NEMA/IP‑only heads in a classified area (no UL 844 marking).
  • Under‑sizing conductors—excess voltage drop at far heads.
  • Placing the power source in an unsuitable ambient (battery derating, charger faults).
  • Missing sealing fittings or damaged/contaminated flame‑path surfaces.

Quick Decision Checklist

  • Heads are UL 844 marked for the exact Class/Div/Group + T‑code
  • Power source location chosen (inside vs outside zone) and listed appropriately
  • Voltage, total load, gauge, and distance meet ≤ 5% drop target
  • NEMA/IP matched to washdown/corrosion needs (if any)
  • 30‑sec and 90‑min tests planned; logs & photos in the commissioning packet

This guide is informational and not a substitute for professional engineering judgment or the authority of your AHJ.