Hazardous-Location Remote Heads: Class I, Division 2 Basics

What C1D2 means (and why it matters)

Class I, Division 2 areas are locations where flammable gases or vapors are present only under abnormal conditions (leaks, maintenance, failure). Remote heads installed in these spaces must be specifically listed for C1D2, including temperature code and enclosure type as applicable. General-purpose or only “wet-location” heads are not enough.

For broader code context and AHJ expectations, see the remote head code requirements overview.

Where the power unit goes (best-practice)

• Prefer unclassified (safe) areas: Mount the remote-capable battery/inverter where it’s not exposed to the classified atmosphere. This simplifies listings, wiring methods, and maintenance.
• If it must be inside the C1D2 space: Use a power unit and accessories that are listed for C1D2, including proper enclosure type. Coordinate with your AHJ on exact labeling and documents.
• Distance to heads: Keep runs as short as practical; long home-runs increase voltage drop and complicate conductor sizing.

Wiring methods & voltage choices

Conductors and fittings: Follow classified-location wiring methods (sealing fittings where required, approved conduit/hubs, proper bonding/grounding). Mark polarity at every termination. For long runs or multiple heads, consider stepping up supply voltage and sizing conductors to control drop.

Choosing supply: compare options in 12V vs 24V for remote heads, then use the wire-gauge & distance tables to pick AWG and confirm one-way distances within your drop limit (often ~5%).

Head selection & environment

• Listing first: Head must be C1D2-listed (and temperature code appropriate to the gas group and ambient).
• Environment: Many hazardous spaces are also wet, dusty, or corrosive. If exposed to weather or washdown, pair C1D2 with a wet-location/IP/NEMA rating—see outdoor IP65 spacing & aiming for mounting/aiming details.
• Compatibility: Verify voltage and load with your remote-capable unit. For mixed families, consult a remote head compatibility matrix before ordering.

Labeling & documentation (what inspectors look for)

• One-line diagram: Show head count, wattage per head, conductor gauge, and run lengths.
• Listings on paper: Include spec sheets showing C1D2 listing, temperature code, and enclosure/hub details for both heads and any in-space power equipment.
• Voltage-drop math: Keep your calculations with assumptions (ambient, design buffer, drop target).
• Test records: 90-minute functional tests with logs retained per local policy.

Inspection checklist (quick pass/fail)

• Correct listing: Heads (and any in-space equipment) marked for C1D2; temperature code appropriate.
• Wiring method: Approved fittings/seals used; polarity and grounds correct.
• Voltage drop: Conductors sized per run length; heads stable at end of line. Use wire-gauge tables as a check.
• Coverage: Aim and overlap beams to avoid dark bands at doors and along the path. If outdoors, apply IP65 spacing & aiming practices.
• Documentation: One-line, listings, and test logs on file; see code requirements overview for what AHJs expect.

This article focuses on hazardous-location (C1D2) basics for remote heads. For fundamentals and step-by-step sizing, use the core remote head sizing & wiring guide.