What is the difference between ATEX and IECEx for control panels?

ATEX is the mandatory EU legal framework under Directive 2014/34/EU, while IECEx is an international certification scheme based on the IEC 60079 series. For control panels, both systems address equipment intended for explosive atmospheres, but ATEX is used for market access in the EU and IECEx is often accepted by global EPCs and multinational operators as a harmonized technical basis. In practice, a hazardous-area panel may be designed to IECEx standards and then assessed for ATEX marking as required. The technical evidence typically references IEC 60079-0, 60079-1, 60079-2, 60079-7, 60079-11, and 60079-31 depending on the protection concept.

Can an IEC 61439 panel be certified for Zone 1 or Zone 21 applications?

Yes, but the IEC 61439 assembly must be engineered around an Ex protection concept and verified accordingly. IEC 61439 covers low-voltage switchgear and controlgear assemblies, so the builder still has to prove temperature rise, short-circuit withstand, clearances, creepage distances, and component coordination. For Zone 1 gas or Zone 21 dust applications, this often means using Ex d, Ex e, Ex p, or Ex i solutions, plus certified glands, terminals, and accessories. The final compliance package usually combines IEC 61439 verification with IEC 60079 hazardous-area requirements and ATEX or IECEx certification of the finished assembly.

Which protection concepts are most common for hazardous-area electrical panels?

The most common concepts are Ex e increased safety, Ex d flameproof, Ex p pressurization, and Ex i intrinsic safety for associated circuits. Ex e is widely used for terminal boxes, junction panels, and motor terminal compartments where arcing parts are minimized. Ex d is common for switching devices, starters, and certain motor control functions because the enclosure can withstand an internal explosion and prevent flame transmission. Ex p is preferred for complete PLC, VFD, or instrumentation cabinets when clean air or inert gas purging can maintain a safe internal atmosphere. Ex i is often used for instrumentation and I/O interfaces with energy-limited circuits.

Do VFD panels need special certification for hazardous areas?

Yes. Variable frequency drive panels in hazardous areas need careful assessment because drives generate heat, harmonics, and sometimes switching transients that affect ignition risk and temperature class. Depending on the installation, the VFD may be housed in a pressurized Ex p enclosure, installed in a non-hazardous area with Ex-certified motor outputs, or incorporated into a certified Ex panel with suitable thermal management. The verification package should address internal losses, fan selection, trip settings, cable glands, segregation, and compliance with IEC 60079 and IEC 61439 requirements. In many projects, the drive manufacturer’s hazardous-area guidance is used alongside the panel builder’s thermal and enclosure verification.

What tests are performed on ATEX/IECEx panel assemblies?

Testing depends on the protection concept, but typically includes routine inspection, dielectric withstand tests where applicable, earth continuity checks, verification of creepage and clearance, and a detailed review of certified components. Ex p panels require purge and pressurization testing, leak checks, alarm and shutdown verification, and validation of minimum overpressure. Ex d assemblies require inspection of flamepaths, fasteners, and enclosure construction. Ex e panels require termination quality, temperature-rise assessment, and mechanical integrity checks. The assembly may also undergo short-circuit verification under IEC 61439 and, where specified, arc-fault containment evaluation per IEC 61641.

Which industries most often require ATEX or IECEx certified panels?

The most common sectors are oil and gas, mining and metals, pharmaceuticals, and food and beverage. In oil and gas, hazardous gas zones around compressors, skids, and processing areas frequently require Ex-rated MCCs, starters, and PLC cabinets. Mining and metals may need dust-rated Ex panels for conveyors, crushers, and filtration systems. Pharmaceuticals and food processing often have dust hazards from powders, batching, drying, and conveying, so Zone 21/22 panels are common. Chemical plants, terminals, tank farms, and wastewater facilities can also require IECEx or ATEX-compliant assemblies, especially where VFDs, soft starters, and protection relays are installed near classified areas.

What information must appear on the Ex marking of a panel?

The Ex marking must identify the equipment group, category, protection concept, gas or dust designation, and temperature class, along with other certification details required by the applicable scheme. For example, a panel may show Group II for surface industries, a category linked to the zone, and markings indicating Ex e, Ex d, Ex p, or Ex i protection. Dust-rated assemblies must include the appropriate dust protection and maximum surface temperature. The marking must match the technical file, certified components, and installation conditions. For ATEX and IECEx projects, the marking is essential because inspectors and end users rely on it to confirm the panel is suitable for the classified area.

How do panel builders demonstrate compliance for a custom Ex control cabinet?

Compliance is demonstrated through a documented design and verification process that ties the hazardous-area classification to the selected protection concept and the final assembly. The builder typically starts with zone classification, gas or dust group, ambient range, and required temperature class. Then the panel is designed using certified components, proper cable entry systems, verified segregation, and thermal management. Evidence may include manufacturer certificates, routine test records, dimensional checks, calculations for heat dissipation and temperature rise, and, where relevant, purge test data or flamepath inspection records. For IEC 61439 assemblies, the builder also has to document electrical performance, short-circuit rating, and construction verification before issuing the final conformity documentation.

Standard

ATEX / IECEx Certification

Explosive atmosphere compliance for hazardous areas

Overview

ATEX / IECEx certification defines the compliance pathway for electrical equipment intended for explosive atmospheres, with direct implications for IEC 61439 panel assemblies used in hazardous areas. ATEX refers to EU Directive 2014/34/EU, while IECEx is the global certification scheme built around the IEC 60079 series. For panel builders, the key issue is not only component selection but also the protection concept, enclosure integrity, thermal management, and documentation package required to prove suitability for the stated Zone, gas/dust group, and temperature class. Typical applications include MCCs, VFD panels, soft-starter panels, PLC automation panels, and custom control cabinets installed in Zone 1/2 gas areas or Zone 21/22 dust areas in oil and gas, mining, pharmaceuticals, and food processing. In practice, hazardous-area panel assemblies may use Ex e increased-safety terminal arrangements, Ex d flameproof enclosures for switching and motor control devices, Ex p pressurized panels with purge and pressurization systems, or Ex i intrinsically safe circuits for low-energy instrumentation interfaces. For IEC 61439-based assemblies, the builder must demonstrate temperature-rise control, creepage and clearance compliance, short-circuit withstand capability, and suitability of internal components such as ACBs, MCCBs, contactors, overload relays, VFDs, soft starters, relays, safety barriers, and protection relays. Many projects also require coordination with IEC 60947 device ratings, enclosure IP/IK performance, and, where applicable, explosive gas or dust conformity under IEC 60079-0, -1, -2, -7, -11, -14, -17, -31, and related parts. A compliant hazardous-area panel is more than a certified enclosure. The complete assembly must be engineered to maintain the integrity of the chosen protection concept under normal operation and predictable fault conditions. For pressurized panels, this includes purge time, minimum overpressure, leakage testing, alarms, interlocks, and safe shutdown logic. For flameproof equipment, flamepath dimensions, fastener integrity, and segregation of live parts are critical. For increased-safety assemblies, the design must avoid arcs, hot surfaces, and loose connections that could ignite a flammable atmosphere. Temperature class limits must be validated against worst-case internal dissipation from drives, power supplies, transformers, and auxiliary circuits, especially in compact PLC and VFD enclosures. Testing and verification may include routine dielectric tests, enclosure checks, internal wiring inspection, thermal assessment, purge/pressurization verification, and review of certified components and cable glands. Depending on the application, additional requirements such as IEC 61641 arc-fault containment, earthing/bonding continuity, and special handling for Ex cables, glands, and barriers may apply. The final product must carry accurate Ex marking, including equipment group, category, protection type, gas or dust designation, and temperature class, supported by a technical file and conformity documentation. For EPC contractors and facility owners, the most common compliance route is to integrate certified Ex components into a panel designed and assembled by a qualified builder, then validate the complete assembly against ATEX, IECEx, and the relevant IEC 61439 performance requirements.