Hazardous Area Zones, EPL and ATEX Categories
Choose a zone to see what it means, which equipment protection levels and ATEX categories are allowed, and the nearest North American Class and Division.
Zones compared
| Zone | Medium | Explosive atmosphere | EPL | ATEX | NEC 500 |
|---|---|---|---|---|---|
| Zone 0 | Gas | Present continuously, for long periods or frequently | Ga | Category 1G | Class I Division 1 |
| Zone 1 | Gas | Likely to occur occasionally in normal operation | Ga or Gb | Category 1G or 2G | Class I Division 1 |
| Zone 2 | Gas | Not likely in normal operation; if it occurs, only for a short time | Ga, Gb or Gc | Category 1G, 2G or 3G | Class I Division 2 |
| Zone 20 | Dust | Present continuously, for long periods or frequently | Da | Category 1D | Class II Division 1 |
| Zone 21 | Dust | Likely to occur occasionally in normal operation | Da or Db | Category 1D or 2D | Class II Division 1 |
| Zone 22 | Dust | Not likely in normal operation; if it occurs, only for a short time | Da, Db or Dc | Category 1D, 2D or 3D | Class II Division 2 |
How Zones, EPL and Categories Fit Together
Area classification (IEC 60079-10-1 for gas, 60079-10-2 for dust) decides the zone. The equipment must then have an equipment protection level (EPL) or ATEX category suitable for that zone.
Equipment rated for a more severe zone may always be used in a less severe one.
In North America the NEC also allows zone classification (Article 505 and 506) alongside the traditional Class and Division system (Article 500). Division 1 covers both zone 0 and zone 1.
Frequently Asked Questions
What is the difference between zone 1 and zone 2?
In zone 1 an explosive atmosphere is likely to occur occasionally in normal operation; in zone 2 it is not expected and, if it occurs, lasts only a short time.
Can zone 1 equipment be used in zone 2?
Yes. Equipment suitable for a more hazardous zone can always be used in a less hazardous one.
How do zones relate to Class I Division 1?
Class I Division 1 corresponds roughly to zone 0 plus zone 1, and Division 2 to zone 2.
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