Can ATEX or IECEx equipment be used in the United States?
Abstract
Not on their own for onshore workplaces. US rules require hazardous location equipment approved for the location, which in practice means certified by an OSHA-recognised NRTL. IECEx reports can shorten US certification; US Coast Guard vessel rules accept IECEx.
Not on their own, for onshore workplaces. US workplace rules require electrical equipment in hazardous (classified) locations to be approved for the location. OSHA defines "approved" mainly as accepted, certified, listed or labelled by a Nationally Recognized Testing Laboratory (NRTL). An ATEX declaration or an IECEx certificate is neither. The equipment needs a US certification and marking, although an IECEx test report can shorten the route. On vessels regulated by the US Coast Guard, IECEx-certified apparatus is accepted under specific rules.
Short answer
- OSHA (29 CFR 1910.307): equipment in hazardous locations must be intrinsically safe, approved for the location, or of a type the employer demonstrates is safe for the location. "Approved" equipment must suit the class, the specific gas, vapour or dust group, and be marked with its temperature.
- "Approved" means NRTL (29 CFR 1910.399): accepted, certified, listed or labelled by an NRTL. Narrow alternatives exist where no NRTL covers that kind of equipment and for custom-made equipment with test data kept by the employer.
- The NEC (NFPA 70), Articles 500 to 506, is the installation code enforced by the local authority having jurisdiction (AHJ) where it has been adopted. It also expects equipment identified for the location.
- US zone equipment is marked
AEx, notEx, for exampleClass I, Zone 1, AEx db IIC T4 Gb. - Exception at sea: 46 CFR 111.105-3 accepts apparatus tested to IEC 60079 and certified under the IECEx System on vessels, alongside NEC-based listed equipment.
Why the European or international certificate is not enough
ATEX conformity is a legal status within the EU: the manufacturer's declaration under Directive 2014/34/EU, backed by a notified body where the category requires. IECEx is an international certification scheme whose certificates have legal force only where a national authority adopts them. Neither is recognised by OSHA as an approval. The certification work is done by private laboratories that OSHA recognises as NRTLs, each for a defined scope of test standards. Each NRTL uses its own registered certification mark on the products it certifies.
The technical gap is smaller than the legal one. The US zone standards are based on the IEC 60079 series with national differences, and the United States is an IECEx member country. A US certifier that is also an IECEx certification body can review an IECEx test report (ExTR) and quality assessment report, test only the national differences and issue a US listing. The result is a new certification with US marking and factory follow-up by the NRTL. It is not an endorsement of the IECEx certificate.
The "safe for the location" route and its limits
29 CFR 1910.307(c)(3) also allows equipment that the employer demonstrates will protect against the hazards of the substances involved, and points to the NEC for guidance. This does not make ATEX or IECEx certificates acceptable as such. It puts the burden of proof on the employer for each item, with records that an OSHA inspector can examine. The local electrical inspector, insurer or owner specification may still require listed equipment. For standard catalogue products, a US-certified variant is usually the practical answer.
How to proceed on a US project
| Situation | What to ask the supplier for |
|---|---|
| Area classified in Class I, Division 1 or 2 | Listing for the class, division, group (A, B, C, D) and temperature code by an NRTL |
| Area classified in Class I, Zone 0, 1 or 2 (NEC 505) | AEx listing for the zone, gas group (IIA, IIB, IIC) and temperature class, or a Division listing the code permits in that zone |
| Vessel under US Coast Guard rules (46 CFR) | IECEx certification to the IEC standards the regulation lists, or NEC-based listing |
| Only ATEX or IECEx available | Ask the manufacturer for a US-certified variant, or for US certification using the IECEx test report |
Example: A European skid arrives for a Texas gas plant with ATEX and IECEx marked instruments, II 2 G Ex db IIC T4 Gb. The plant is classified Class I, Division 2, Group D. The marking shows good technical protection, but none of the items carries an NRTL mark. The owner asks the supplier to swap them for versions with US listings, for example Class I, Zone 1, AEx db IIC T4 Gb, which the NEC permits in a Division 2 location of the matching group. Items with no US-certified variant are certified by an NRTL using their IECEx reports, or replaced.
Common mistakes
- "IECEx is international, so it covers the US." The US participates in IECEx, but onshore law asks for NRTL approval.
- Accepting dual
ExandAExlines without the NRTL mark. The marking must be backed by the laboratory's registered certification mark. - Forgetting the zone-division rule. Zone 1 listed equipment may not be installed in Division 1; check the NEC rules for the classification used.
Related on excodex
- North American hazardous location approvals: NEC 500/505/506, UL, CSA and FM
- ATEX vs IECEx: differences, similarities and which one you need
- Can Class I Division 1 approved equipment be used in an ATEX Zone 1?
- What does AEx mean on North American hazardous location equipment?
- Standards spaces: NEC 500 to 506, IECEx
Standards and further reading
- 29 CFR 1910.307, hazardous (classified) locations: osha.gov
- 29 CFR 1910.399, definitions of approved, acceptable, listed and labeled: osha.gov
- OSHA Nationally Recognized Testing Laboratory program: osha.gov
- 46 CFR 111.105-3, approval of equipment in hazardous locations on vessels: law.cornell.edu
- NFPA 70, National Electrical Code, Articles 500 to 506 (hazardous locations)
This article is general technical information prepared by the excodex editorial team. It does not replace the applicable standards, the equipment certificates and instructions, national regulations or the assessment of a competent person.