---
pretty_name: "North American vs IEC/ATEX explosion protection designations"
license: other
license_name: source-terms-cited
license_link: https://referencesource.org/ex-classification-system-crosswalk/
language:
- en
tags:
- reference-data
- provenance
- referencesource-org
configs:
- config_name: default
  data_files:
  - split: train
    path: data/records.jsonl
---
# North American vs IEC/ATEX explosion protection designations

**Canonical, always-current version: https://referencesource.org/ex-classification-system-crosswalk/**
Machine-readable: https://referencesource.org/ex-classification-system-crosswalk/data.json — this mirror is a point-in-time copy.

- **Last verified:** 2026-08-06
- **Stale after:** 2028-08-05 (past this date, prefer the canonical copy —
  it re-verifies on a cadence this snapshot does not)
- **Records:** 128

Crosswalk between the two concurrent hazardous-area classification systems: the North American Class / Division system of NEC Articles 500 and 505 (NFPA 70) and the CSA code, against the Zone system of IEC 60079, ATEX and IECEx. Each record is one designation in one system with its stated counterpart in the other, covering area classification (Division 1 and 2 against Zone 0, 1, 2, 20, 21, 22), gas groups (A, B, C, D against IIA, IIB, IIC, IIB+H2), dust groups (E, F, G against IIIA, IIIB, IIIC), protection concepts (explosion-proof against Ex d, intrinsically safe against Ex i, purged/pressurized against Ex p, dust-ignition-proof against Ex t, non-incendive against Ex nA/Ex ec) with the IEC standard number for each, and temperature codes T1 to T6 with their maximum surface temperatures. It also carries the equipment marking codes themselves -- the NEC 500 bracket codes (XP), (IS), (NI), (DIP), (PX), (PY), (PZ) and the NFPA 496 purge Types X, Y and Z, against the NEC 505 and CEC Ex / AEx codes -- each with the country whose column printed it, the hazard class and division or zone it is approved for, and the ISA, UL, FM, NFPA or CSA standard behind it, because the same code means different standards either side of the border: (IS) is UL 913 / FM 3610 in the US and C22.2 No. 157 in Canada. Answers 'is ATEX Ex d IIB T4 the same as Class I Div 1 Group C', 'what does T2D mean and is there an IEC equivalent', 'Division 1 or Zone 1 which is stricter', 'NEC Group B IEC equivalent', and 'can I install Zone 1 equipment in a Division 1 area'. Three things the mapping gets wrong when stated as a simple table: NEC 500 has no Zone 0 equivalent so Division 1 spans Zone 0 and Zone 1 and is under-specified for Zone 0; the North American temperature codes T2A, T2B, T2C, T2D, T3A, T3B, T3C and T4A have no IEC counterpart at all; and publishers disagree on NEC Group B, giving it as IIC or as IIB+H2, which changes the required flameproof gap. Every counterpart is quoted from the page that stated it and attributed, so the disagreement is visible.

## Provenance — what every record carries

Every record carries `source` (the URL the value was read from) and
`source_quote` (a verbatim quote from that page stating it). A value you
cannot check against its page is indistinguishable from an invented one;
these can all be checked. Each record is also individually addressable on
the canonical site at its `url`.

## Licence position

Facts extracted from freely published manufacturer and industry reference pages. Designation crosswalks are safety facts, not copyrightable expression. NFPA 70 and the IEC 60079 series are not reproduced and were not opened -- the fact is taken, never the document. Four separate publishers, no bulk take from any one.

Facts are not copyrightable; what this dataset takes from each source is a
fact plus a short attributed quote linking back to the page that states it.

## Sources

- https://exknowledge.com/pages/nec-500-vs-atex-iec.html
- https://www.euroswitch.com/wp-content/uploads/euroswitch-hazardous-area-guide_V6.pdf
- https://www.inframena.com/hazardous-area-classification-equivalency-guide/
- https://www.e2s.com/guide-for-hazardous-areas/gas-and-dust-groups
- https://ldpi-inc.com/resources/classification-codes/class-1-locations/

## Fields

See any record in `data/records.jsonl` — field names are self-describing,
and the canonical page for each record renders them with labels:
https://referencesource.org/ex-classification-system-crosswalk/