# C — Certification marks and hazardous-area classifications: cross-market equivalences

For C, stated equivalent is IIB; applies to is Ethylene, ethyl ether, verified against its source on 2026-08-11.

- **Designation:** C _(verified: appears in the quote below)_
- **Stated equivalent:** IIB _(verified: appears in the quote below)_
- **Applies to:** Ethylene, ethyl ether _(verified: appears in the quote below)_

## What the source says

> C | IIB | Ethylene, ethyl ether | 0.50–0.90 mm

## Source

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

Last verified: 2026-08-11. Review by: 2027-08-11.
Part of [Certification marks and hazardous-area classifications: cross-market equivalences](https://referencesource.org/certification-standards-equivalence/).