Certification for hazardous areas is not a test a finished product passes. It is a constraint set that governs the design from the first enclosure sketch, and it is written by the environment rather than by the product. The equipment is not the variable in that calculation. The atmosphere is, and it was classified before anyone chose a housing, a battery, or a thermal budget.

The zone determines the category, the category determines the fault tolerance the design must carry, and that chain makes certification a decision taken before the design starts rather than after it finishes.

What ATEX Certification Is, and What It Governs

ATEX takes its name from the French atmosphères explosibles. It is a legal prerequisite for placing equipment on the market in the European Economic Area (EEA), not a voluntary quality mark. Two directives sit behind the name, and they address different parties:

1. Directive 2014/34/EU (ATEX 114): governs manufacturers of equipment and protective systems intended for use in explosive atmospheres, and sets the conformity assessment routes.
2. Directive 1999/92/EC (ATEX 137): governs operators of workplaces where explosive atmospheres can occur, and places the duty to classify areas and control ignition sources on the employer.

An original equipment manufacturer (OEM) carries the obligation under the first. The requirement exists because an ignition source in a flammable gas or combustible dust environment is a fatality risk rather than a warranty risk.

ATEX and IECEx Are Not the Same Instrument

Geography is the usual shorthand for the difference, and it is the least useful part of it. The mechanisms differ. IECEx is an international scheme run under the International Electrotechnical Commission (IEC), in which a certification body assesses the product, supervises production on an ongoing basis, and issues a certificate verifiable in a live public database. ATEX is a hybrid: the manufacturer issues the Declaration of Conformity, and for some equipment categories can self-declare without involving a Notified Body.

Most manufacturers pursue both at once, because the technical requirements largely align. Great Britain adds a third route, the UKEX scheme under UK Conformity Assessed (UKCA) marking, built on technical content that mirrors ATEX. One design, three certification routes.

Zones, Groups, and Categories: How the Requirement Is Set

The classification chain runs in one direction, and every downstream design decision inherits from it. The operator classifies the area. The equipment category follows from that classification. A manufacturer does not select its own protection level; it reads the level off the zone its customer works in.

• Equipment groups: Group I covers mining applications, Group II covers all other surface industries.
• Gas zones: Zone 0 where an explosive atmosphere is present continuously or for long periods, Zone 1 where it is likely in normal operation, and Zone 2 where it is unlikely and brief.
• Dust zones: Zones 20, 21, and 22, following the same continuous, likely, and unlikely gradation for combustible dust.
• Equipment categories: Category 1 for Zones 0 and 20, which must remain safe with two independent faults present; Category 2 for Zones 1 and 21, safe with one fault; and Category 3 for Zones 2 and 22, safe in normal operation.
• Gas and temperature classification: gas groups IIA, IIB, and IIC ranked by ignition energy, alongside temperature classes T1 to T6 capping the equipment's maximum permitted surface temperature, from 450 degrees Celsius down to 85.

A Category 1 requirement is therefore a two-fault-tolerant design, and fault tolerance is architectural: it lives in redundancy, energy limitation, and separation, all fixed in the first schematic and the first enclosure model. Retrofitting it into a design scoped for Category 3 is a redesign, not a revision.

What Certification Demands of the Design

The protection concepts are design strategies rather than labels applied at the end, and the choice between them determines the mechanical and electrical architecture of the product. 

• Ex d, flameproof enclosure: contains an internal explosion within the housing and cools escaping gases below the ignition temperature of the surrounding atmosphere.
• Ex e, increased safety: prevents arcs, sparks, and hot surfaces from occurring at all, through creepage, clearance, and connection design.
• Ex i, intrinsic safety: limits the energy available in the circuit below the ignition threshold, and is the only route into Zone 0.
• Ex m, encapsulation: embeds the potential ignition source in a compound that keeps the atmosphere off it.
• Ex p, pressurisation: excludes the atmosphere with clean-air overpressure inside the enclosure.

Each concept charges the design for the protection it gives. Flameproof housings impose wall thickness, flame path length and tolerance, and joint geometry that sit squarely in mechanical engineering rather than in electronics, and the resulting mass and thermal behaviour change the whole product.

Intrinsic safety constrains stored energy across the entire system. It limits battery chemistry and capacity, caps capacitor values, and puts a ceiling on cable capacitance and inductance, which turns a routine cable length change into a certification question.

The temperature class sets a hard ceiling on component surface temperature under fault conditions, not under nominal load. Thermal design and derating become certification inputs rather than performance preferences, and a part that runs comfortably at rated load can still fail on its fault-condition surface temperature.

For connected equipment, antenna placement and enclosure material are constrained at once by radio frequency (RF) performance and by ingress and flame path requirements. A metal flameproof housing is a hostile environment for an internal antenna, and any window or moulded insert has to satisfy the flame path calculation as well as the radiation pattern. Resolving both at once is where hazardous-area hardware is won or lost.

Type Examination, Production Quality, and Why the Build Matters

Certification has two halves, and the second is the one most teams underestimate. EU-type examination assesses and tests a representative sample against the applicable standards and produces a certificate describing that sample. Production quality assurance, or product verification depending on the route, confirms every subsequent unit is identical to the type assessed.

A certificate covers a design as it was built, so a component substitution, an unapproved supplier change, or a drift in a controlled process invalidates the conformity of the units affected, whether or not anyone notices. Hazardous-area hardware does not degrade in a way a returns analysis catches. It holds, until an ignition source that was engineered out reappears through a change nobody assessed.

Traceability, controlled change management, and a maintained technical file therefore carry the same weight as the original test report. That is what makes the manufacturing partner part of the compliance position rather than a downstream executor of it, since the risk sits with whoever signed the Declaration of Conformity.

How PCI Supports Hardware Built for Hazardous Areas

PCI is an electronics manufacturing services (EMS) specialist with over 50 years of experience, designing and manufacturing to hazardous-area requirements and supporting the certification path. The certificate itself is issued by a Notified Body; the work that makes it achievable happens earlier:

• Electronic hardware design and component selection: parts chosen and derated against the applicable temperature class and, where intrinsic safety applies, against system energy limits.
• Mechanical and enclosure design: ingress protection, ruggedisation, and housing architecture developed alongside the thermal model rather than after it.
• RF and radio-wave engineering: antenna design and placement for connected equipment inside constrained, often conductive enclosures.
• Design verification and test development: coverage built to demonstrate behaviour under fault conditions rather than functional performance alone.
• Controlled manufacturing with full traceability: unit-level traceability and change control under ISO 9001, IATF 16949, and ISO 13485.

The constraints that decide whether a product certifies are set at design stage, and the discipline that keeps it certified is set on the production line. A manufacturing partner engaged before the enclosure and power architecture are frozen changes the outcome at the only point where change is still cheap. 

If you have hardware destined for a hazardous-area application, talk to PCI as your electronics manufacturing partner.

Frequently Asked Questions

What does ATEX mean?

ATEX is short for atmosphères explosibles, the French term for explosive atmospheres. It refers to two European Union directives covering equipment and workplaces where flammable gases, vapours, mists, or combustible dusts can create an explosion risk. In everyday use, ATEX describes equipment certified as safe to operate inside those classified areas.

What is ATEX certification for?

It demonstrates that equipment intended for an explosive atmosphere will not become an ignition source in the zone it is rated for. Certification fixes the equipment category, the protection concept, the gas group, and the temperature class, so an operator can match a device to the area classification of the workplace it enters.

What is the difference between ATEX and IEC?

ATEX is European Union law and applies to equipment placed on the market in the European Economic Area. IECEx, run under the International Electrotechnical Commission, is a voluntary international scheme with ongoing production surveillance by the certification body and a publicly verifiable certificate database. The technical requirements largely align, so most manufacturers pursue both.

Why is ATEX certification required?

An ignition source in a flammable atmosphere is a fatality risk, so conformity is a legal condition of sale rather than a quality option. Placing non-compliant equipment in a classified area exposes both the manufacturer and the operator to enforcement action, and it removes the assurance that the workplace area classification depends on.