Hazardous Areas
Zones & Equipment Matching
Check whether an equipment marking is acceptable for a hazardous area. Reference values are illustrative; confirm against the current standard.
Marking checker
✓ Acceptable for Zone 1
Accepted: EPL Ga / Gb · ATEX category 1G / 2G · Equivalent: NEC 505 Zone 1 / Class I Div 1 · IEC 60079-10-1 §3.3.2
Area classifications
| Area | System | Description | Accepted EPL | Equivalent |
|---|---|---|---|---|
| Zone 0 | IEC/ATEX | Explosive gas atmosphere present continuously or for long periods. IEC 60079-10-1 §3.3.1 | Ga | NEC 505 Zone 0 / Class I Div 1 (part) |
| Zone 1 | IEC/ATEX | Explosive gas atmosphere likely in normal operation occasionally. IEC 60079-10-1 §3.3.2 | Ga, Gb | NEC 505 Zone 1 / Class I Div 1 |
| Zone 2 | IEC/ATEX | Not likely in normal operation; if it occurs, only for a short period. IEC 60079-10-1 §3.3.3 | Ga, Gb, Gc | NEC 505 Zone 2 / Class I Div 2 |
| Zone 20 | IEC/ATEX | Combustible dust cloud present continuously or frequently. IEC 60079-10-2 §3.3 | Da | NEC 506 Zone 20 / Class II Div 1 |
| Zone 21 | IEC/ATEX | Combustible dust cloud likely occasionally in normal operation. IEC 60079-10-2 §3.3 | Da, Db | NEC 506 Zone 21 / Class II Div 1 |
| Zone 22 | IEC/ATEX | Dust cloud not likely in normal operation; short periods only. IEC 60079-10-2 §3.3 | Da, Db, Dc | NEC 506 Zone 22 / Class II Div 2 |
| Class I Div 1 | NEC | Ignitable gas/vapor concentrations exist under normal operation. NFPA 70 Art. 500.5(B)(1) | Ga, Gb | IEC Zone 0 + Zone 1 |
| Class I Div 2 | NEC | Ignitable concentrations only under abnormal conditions. NFPA 70 Art. 500.5(B)(2) | Ga, Gb, Gc | IEC Zone 2 |
| Class II Div 1 | NEC | Combustible dust in suspension under normal operation. NFPA 70 Art. 500.5(C)(1) | Da, Db | IEC Zone 20 + Zone 21 |
| Class II Div 2 | NEC | Dust accumulations/suspension only under abnormal conditions. NFPA 70 Art. 500.5(C)(2) | Da, Db, Dc | IEC Zone 22 |
| Explosives Area | DoD | Exposed explosives or propellant dust; NEC Class II Div 1 minimum per DESR, plus explosives-specific rules. DESR 6055.09 V2 §E3 | Da, Db | DESR 6055.09 V2 Encl. 3 hazardous locations |
Dust group
IIIA Combustible flyings.
e.g. Fibers
IIIB Non-conductive dust.
e.g. Nitrocellulose dust, propellant fines, flour
IIIC Conductive dust.
e.g. Aluminum, magnesium powder
Gas group
IIA Least easily ignited gases (IEC). NEC Group D.
e.g. Propane, acetone, ethanol, solvents
IIB Intermediate (IEC). NEC Group C.
e.g. Ethylene, diethyl ether
IIC Most easily ignited (IEC). NEC Groups A/B.
e.g. Hydrogen, acetylene
Temperature class
T1 Max surface 450 °C
T2 Max surface 300 °C
T3 Max surface 200 °C
T4 Max surface 135 °C
e.g. Diethyl ether
T5 Max surface 100 °C
T6 Max surface 85 °C
e.g. Carbon disulfide