# NEC 505 — Certification marks and hazardous-area classifications: cross-market equivalences

For NEC 505, market / system is US; meaning is NEC 505 (Zone-based) is accepted in the US and provides easier mapping from IEC zones, verified against its source on 2026-08-11.

- **Designation:** NEC 505 _(verified: appears in the quote below)_
- **Market / system:** US _(verified: appears in the quote below)_
- **Meaning:** NEC 505 (Zone-based) is accepted in the US and provides easier mapping from IEC zones _(verified: appears in the quote below)_

## What the source says

> NEC 505 (Zone-based) is accepted in the US and provides easier mapping from IEC zones

## 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/).