# Class I (gas), II (dust), III (fibers) — North American vs IEC/ATEX explosion protection designations

For Class I (gas), II (dust), III (fibers), category is system attribute; iec / atex designation is Zone 0, 1, 2 (gas); Zone 20, 21, 22 (dust); basis or note is Hazard basis, recorded from its source on 2026-08-06.

- **Category:** system attribute _(our reading, not quoted from the source)_
- **North American designation:** Class I (gas), II (dust), III (fibers) _(verified: appears in the quote below)_
- **IEC / ATEX designation:** Zone 0, 1, 2 (gas); Zone 20, 21, 22 (dust) _(verified: appears in the quote below)_
- **Basis or note:** Hazard basis _(verified: appears in the quote below)_

## What the source says

> Hazard basis | Class I (gas), II (dust), III (fibers) | Zone 0, 1, 2 (gas only) | Zone 0, 1, 2 (gas); Zone 20, 21, 22 (dust)

## Source

- https://exknowledge.com/pages/nec-500-vs-atex-iec.html

Last verified: 2026-08-06. Review by: 2028-08-05.
Part of [North American vs IEC/ATEX explosion protection designations](https://referencesource.org/ex-classification-system-crosswalk/).