Hazardous area standards govern electrical equipment and installations in locations where flammable gases, vapors, dusts, or fibers may be present. Two parallel systems exist — the IEC Zone system (international) and the NEC Class/Division system (US).

Classification Systems

System Standard Zones/Classes Used In
IEC Zone (gas) IEC 60079-10-1 Zone 0, 1, 2 International, US Art. 505
IEC Zone (dust) IEC 60079-10-2 Zone 20, 21, 22 International
NEC Division (gas/dust) NEC Art. 500–503 Class I/II/III, Division 1/2 US (traditional)
NEC Zone (IEC-aligned) NEC Art. 505–506 Zone 0/1/2, Zone 20/21/22 US (IEC-aligned)

Both systems are valid in the US. IEC Zone is preferred for projects using ATEX/IECEx certified equipment.

Standards in This Family

Standard Scope Corpus Status
IEC 60079 (6 parts) Explosive atmosphere equipment and installation Complete
NEC Art. 500–505 US hazardous location wiring See NEC page

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