What is required to certify a PLC and automation control panel for ATEX or IECEx?

Certification depends on the intended hazardous area, protection concept, and installed equipment. The panel design must be evaluated against IEC 60079-0 and the relevant protection standards such as IEC 60079-7, -11, -15, -1, or -31, depending on whether the assembly uses Ex e, Ex i, Ex d, Ex p, or Ex t methods. The technical file typically includes drawings, BOM, temperature-rise calculations, terminal and gland details, marking, and installation instructions. For the low-voltage assembly portion, IEC 61439 principles are also used to verify the panel’s electrical performance, short-circuit withstand, and internal separation arrangement. In practice, certification is not just a label; it is a documented conformity process tied to the exact build configuration.

Can PLCs, HMIs, and VFDs be installed inside an ATEX or IECEx panel?

Yes, but only if the installation concept and location permit it. PLCs, HMIs, industrial switches, VFDs, and soft starters are usually installed in a safe area enclosure or in a protected Ex p cabinet, or they are connected through certified intrinsic safety barriers or isolators. If the panel is in a classified zone, each device must be assessed for its ignition-risk contribution, surface temperature, and suitability for the zone and gas group. VFDs and braking resistors are particularly critical because they generate heat and may need derating or external mounting. IEC 60079-14 is commonly used for installation requirements, while IEC 60079-0 and the applicable protection-specific standard govern the equipment selection and marking.

What tests are performed on a hazardous-area control panel during verification?

Verification usually includes visual inspection, dimensional checks, earthing continuity, insulation resistance, dielectric withstand where applicable, and verification of creepage, clearance, and segregation. For flameproof or pressurized concepts, additional checks can include enclosure integrity, pressure leakage, and clearance of flamepaths or purge systems. Thermal assessment is essential, especially where PLC power supplies, contactors, VFDs, and UPS modules are densely packed. Environmental checks such as IP rating, ingress protection, and corrosion resistance may also be required. For the switchgear portion, IEC 61439 verification methods are used to confirm design robustness, while the hazardous-area portion is validated against IEC 60079 series requirements and the relevant ATEX/IECEx certification route.

How does temperature class affect the design of an ATEX PLC panel?

Temperature class determines the maximum allowable surface temperature of the equipment so it cannot ignite the surrounding atmosphere. This has direct impact on enclosure sizing, device placement, heat dissipation, and permissible loading. For example, a panel intended for T4 service must ensure that the hottest accessible surface stays below 135°C under worst-case conditions. Internal devices such as power supplies, relays, MCCBs, and communication modules all contribute to heat rise, and VFDs can dominate the thermal profile. Designers often use larger enclosures, forced ventilation only where allowed, derating, or remote mounting of heat-producing components. The temperature evaluation is documented in the technical file and tied to the final certified configuration.

What documentation is needed for IECEx certification of a control panel?

A complete IECEx documentation package typically includes the hazardous-area classification basis, equipment drawings, wiring diagrams, BOM with certified part numbers, marking details, thermal calculations, installation and maintenance instructions, and the conformity assessment records. If the panel uses multiple protection concepts, the documentation must clearly identify each circuit and its protection method. The technical file also needs evidence of component certificates, such as Ex certified glands, terminals, barriers, or enclosures, along with the manufacturer’s controls for change management. For panel builders, maintaining revision control is critical because even a small component change can invalidate the assessed configuration unless re-evaluated under the applicable IECEx or ATEX procedure.

What is the difference between ATEX and IECEx for panel assemblies?

ATEX is the European regulatory framework for equipment used in explosive atmospheres, while IECEx is an international conformity assessment system based on IEC standards. In practical panel design, both systems rely heavily on the IEC 60079 series, but ATEX is tied to EU legal requirements and marking, whereas IECEx is a globally recognized certification pathway used by many EPCs and OEMs. For a PLC & Automation Control Panel, the engineering content is often similar: hazardous-area classification, protection concept selection, thermal assessment, and certified component integration. The main difference is in the certification and market access route, not the core electrical design principles.

How are maintenance and modification handled after ATEX or IECEx certification?

Post-certification changes must be controlled through a formal change management process. Replacing a relay, adding a communication module, changing a gland, or upgrading a power supply may affect temperature rise, protection integrity, or certification traceability. Maintenance should follow the original instructions, with periodic inspection intervals based on the area classification and operating environment. Under IEC 60079-17, inspections focus on condition, damage, and continued suitability, while any repair or overhaul should preserve the certified protection concept. For panel builders and facility managers, this means keeping as-built records, spare-part control, and re-assessment procedures so the installed panel remains compliant throughout its lifecycle.

Which panel components are most critical for hazardous-area compliance?

The most critical components are the enclosure, cable glands, terminal blocks, power supplies, protective devices, and any heat-generating automation equipment. In many cases, MCCBs, contactors, relays, PLC racks, HMIs, and VFDs are not inherently hazardous-area rated unless installed within a suitable protection concept or safe area arrangement. Certified glands, earth terminals, segregated wiring ducts, and barriers or isolators for intrinsically safe circuits are also essential. The final compliance outcome depends on the exact combination of parts and their certified use conditions, so even components with valid individual certificates must be assembled in a way that preserves the overall ATEX or IECEx protection basis.

Panel + Standard

PLC & Automation Control Panel — ATEX / IECEx Certification Compliance

ATEX / IECEx Certification compliance requirements, testing procedures, and design considerations for PLC & Automation Control Panel assemblies.

Overview

ATEX and IECEx certification compliance for PLC & Automation Control Panel assemblies is a specialized engineering discipline that combines low-voltage switchgear design with hazardous-area protection principles. For panels installed in explosive atmospheres, the enclosure, internal components, wiring methods, thermal performance, and documentation must be assessed against the applicable protection concept and installation zone. In practice, this means the panel builder must define whether the assembly is intended for Zone 1 or Zone 2 gas atmospheres, or for Zone 21 or Zone 22 combustible dust areas, then verify the equipment category, temperature class, and maximum surface temperature. IEC 60079 series requirements are central, particularly IEC 60079-0 for general requirements, IEC 60079-1 for flameproof enclosures, IEC 60079-7 for increased safety, IEC 60079-11 for intrinsic safety, IEC 60079-15 for non-sparking equipment, and IEC 60079-31 for dust ignition protection by enclosure. Unlike ordinary industrial panels, a certified PLC & Automation Control Panel may require segregated construction for different circuits. Typical architectures include main power distribution with MCCBs, control power via DIN-rail power supplies, safety circuits with safety relays, and automation islands containing PLCs, remote I/O, HMI panels, industrial Ethernet switches, VFDs, soft starters, and protection relays. Each component must be suitable for the hazardous area concept used or mounted in a safe area with approved interfaces such as Ex i barriers, galvanic isolators, or certified glands and terminal systems. Where electric motors are started or speed-controlled inside the system, the selected VFD or soft starter must be evaluated for heat dissipation, fault energy, and suitability in the intended zone. In many applications, design choices are constrained by current rating, short-circuit withstand capability, and maximum internal temperature rise, especially when high-density PLC racks and communication modules are installed. Certification work typically includes design review, type testing, temperature rise evaluation, ingress protection verification, impact resistance, and assessment of creepage, clearance, and wiring segregation. For assembly verification, IEC 61439 principles remain relevant to the low-voltage switchgear portion of the panel, while explosion-protection compliance is demonstrated through the relevant IECEx or ATEX certification route. Depending on the concept, the enclosure may need Ex d, Ex e, Ex p, or Ex t protection, with cable entries, terminal blocks, labels, and associated equipment all documented in the technical file. Special attention is required for forms of separation between energized circuits, intrinsically safe and non-intrinsically safe wiring, and heat-generating devices such as power supplies, line reactors, and braking resistors. Real-world applications include oil and gas compressor skids, chemical dosing stations, grain handling plants, paint booths, tank farms, and dust-prone process areas where an automation panel must operate reliably without becoming an ignition source. For EPC contractors and panel builders, compliance also includes traceable component selection, manufacturer declarations, risk assessment, inspection schedules, and maintenance of the Ex marking over the asset life cycle. A properly engineered PLC & Automation Control Panel for hazardous areas is not only a matter of passing certification; it is a lifecycle system that must remain compliant after modifications, replacements, and periodic inspections.

Key Features

ATEX / IECEx Certification compliance pathway for PLC & Automation Control Panel
Design verification and testing requirements
Documentation and certification procedures
Component selection for standard compliance
Ongoing compliance maintenance and re-certification

Specifications

Panel Type	PLC & Automation Control Panel
Standard	ATEX / IECEx Certification
Compliance	Design verified
Certification	Per applicable verification method

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PLC & Automation Control Panel

ATEX / IECEx Certification

Frequently Asked Questions

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