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

For Ex, market / system is US; stated equivalent is Zone 20, 21, 22; governing standard / law is ISA 60079-0, verified against its source on 2026-08-11.

- **Designation:** Ex _(verified: appears in the quote below)_
- **Market / system:** US _(verified: appears in the quote below)_
- **Stated equivalent:** Zone 20, 21, 22 _(verified: appears in the quote below)_
- **Governing standard / law:** ISA 60079-0 _(verified: appears in the quote below)_

## What the source says

> Ex US Zone 20, 21, 22 ISA 60079-0

## Source

- https://www.euroswitch.com/wp-content/uploads/euroswitch-hazardous-area-guide_V6.pdf

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/).