North American vs IEC/ATEX explosion protection designations

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. 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.

18 records where two or more sources state different values. Both sides are reproduced on the record page, each with its own source and quote.

The data

Where this came from

Every record above links the page it was taken from and quotes the sentence that states it. These are the 4 sources this dataset was assembled from.

• exknowledge.comhttps://exknowledge.com/pages/nec-500-vs-atex-iec.html
• inframena.comhttps://www.inframena.com/hazardous-area-classification-equivalency-guide/
• e2s.comhttps://www.e2s.com/guide-for-hazardous-areas/gas-and-dust-groups
• ldpi-inc.comhttps://ldpi-inc.com/resources/classification-codes/class-1-locations/

Machine-readable

• data.jsonThe whole dataset — every record with its source URL and source quote.
• Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
• How this is made and checkedWhat "verified against source" does and does not mean.

65 records. last verified against source 2026-08-06. due for re-check by 2028-08-05.

Licence. 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.