IECEx Certification: Zones and Protection Concepts
(Ex d, Ex e, Ex i)
Introduction: The Foundation of Explosion Safety
Understanding IECEx Zones and Protection Concepts is not just about compliance—it is the foundation of preventing catastrophic industrial explosions. The IECEx Certification System is a globally accepted framework ensuring electrical equipment is designed, manufactured, and maintained safely in environments containing flammable gases, vapours, or combustible dusts.
The IEC system provides a worldwide framework for explosion safety, facilitating international market access and harmonizing requirements for hazardous locations.
This guide explains key concepts such as the link between Hazardous Area Classification (Zones), Equipment Protection Levels (EPLs), and Protection Concepts like Ex d, Ex e, and Ex i, which ensure safety under the IEC 60079 series. It also explores compliance with both ATEX and IECEx
and their alignment with European standards.
Explosion Fundamentals: The Triangle of Risk
Before selecting equipment, understand how an explosion occurs. The Explosion Triangle shows three essential components:
- Fuel: Flammable gas, vapour, or dust.
- Oxygen: Typically air.
- Ignition Source: Spark, hot surface, or electrical arc.
Explosion protection removes the ignition source—even in fault conditions. IECEx Protection Concepts use engineering methods to achieve this, ensuring safety in hazardous areas.
What Are IECEx Zones? (Hazardous Area Classification)
The IECEx System classifies hazardous areas into zones based on how often an explosive atmosphere may be present. This classification is the first step in managing hazardous areas.
| Zone Type | Description | Atmosphere Type |
|---|---|---|
| Zone 0 | Explosive gas atmosphere present continuously or for long periods. | Gas/Vapour |
| Zone 1 | Likely to occur occasionally during normal operation. | Gas/Vapour |
| Zone 2 | Unlikely to occur, or only for short durations. | Gas/Vapour |
| Zone 20 | Continuous presence of combustible dust. | Dust |
| Zone 21 | May occur occasionally with combustible dust. | Dust |
| Zone 22 | Unlikely or short-duration presence of combustible dust. | Dust |
Key takeaway: Lower zone numbers (0 or 20) represent higher risk, requiring equipment with stricter protection levels.
Equipment Protection Levels (EPLs)
Equipment Protection Levels (EPLs) define the inherent safety built into equipment for hazardous zones. They guarantee safe operation even under fault conditions.
| EPL Code | Protection Level | Applicable Zone | Failure Tolerance |
|---|---|---|---|
| Ga | Very High | Zone 0 | Safe with two independent faults. |
| Gb | High | Zone 1 | Safe with one single fault. |
| Gc | Enhanced | Zone 2 | Safe during normal operation. |
| Da | Very High | Zone 20 | Safe with two independent faults. |
| Db | High | Zone 21 | Safe with one single fault. |
| Dc | Enhanced | Zone 22 | Safe during normal operation. |
Understanding IECEx Protection Concepts
Protection Concepts define engineering methods that achieve the required equipment protection level (EPL). Each concept corresponds to an IEC 60079 standard that governs design and testing.
Flameproof Enclosure (Ex d)
Standard: IEC 60079-1
Principle: Containment of internal explosions.
Feature: Flamepaths cool escaping gases below ignition temperature.
Use: Motors, switchgear, control stations.
Zones: Zone 1 and Zone 2 (Gb, Gc).
Increased Safety (Ex e)
Standard: IEC 60079-7
Principle: Prevention of arcs and high temperatures.
Feature: Larger clearances, high-insulation materials.
Use: Junction boxes, terminals, lighting fixtures.
Zones: Zone 1 and Zone 2 (Gb, Gc).
Intrinsic Safety (Ex i)
Standard: IEC 60079-11
Principle: Energy limitation to prevent ignition.
Feature: Barriers limit energy reaching hazardous areas.
Use: Sensors, instrumentation, communication circuits.
Zones: Zone 0, 1, and 2 (Ga, Gb, Gc).
Other Protection Concepts
| Designation | Protection Method | Principle | Typical Use |
|---|---|---|---|
| Ex p | Pressurization | Maintains protective gas pressure inside the enclosure. | Motors, analyser houses, control panels. |
| Ex t | Protection by enclosure (Dust) | Prevents dust ingress and limits temperature. | Equipment in Dust Zones 20, 21, 22. |
Decoding the IECEx Marking Code
All Ex-certified equipment has a marking code defining its type, protection concept, and suitability. Example:
Example marking: Ex db IIC T6 Gb
| Part | Description | Meaning |
|---|---|---|
| Ex | Certified for explosive atmospheres | Standard indicator |
| db | Protection Concept | Flameproof enclosure (Ex d) with enhanced level “b” |
| IIC | Gas Group | For hydrogen or acetylene (most severe) |
| T6 | Temperature Class | Max surface temperature 85°C |
| Gb | EPL | Suitable for Zone 1 (high protection) |
Pro Tip: Always ensure the T-Class is lower than the auto-ignition temperature of the target gas or dust.
Hazardous Area Classification Process
- Identify all sources of release, such as vents or seals.
- Determine grade of release (continuous, primary, secondary).
- Calculate zone extent using IEC 60079-10 standards.
- Assign the appropriate zone classification (0–2 or 20–22).
- Select certified equipment with matching EPL and T-Class.
Proper classification improves safety, reduces costs, and ensures compliance.
Key IEC Standards
- IEC 60079-0: General requirements
- IEC 60079-10-1: Gas hazardous area classification
- IEC 60079-10-2: Dust hazardous area classification
- IEC 60079-14: Electrical installations design and maintenance
- IEC 60079-17: Inspection and maintenance competence
- IEC 60079-1 / -7 / -11: Standards for Ex d, Ex e, Ex i protection methods
The Role of Certification Bodies
IECEx Certification Bodies ensure products meet explosion safety standards. They independently test and certify equipment, assess quality control systems, and issue IECEx Certificates of Conformity for global market access.
By working with accredited certification bodies, manufacturers benefit from improved product safety, simplified compliance, and faster market entry.
Common Mistakes in Ex Equipment Installation
| Mistake | Consequence |
|---|---|
| Mixing Standards | Using Class/Division rules with IECEx Zones causes incompatibilities. |
| Loose Ex d Flamepaths | Allows hot gases to escape, risking ignition. |
| Incorrect Cable Glands | Compromises flameproof or sealing integrity. |
| Oversized Ex i Circuits | Exceeds energy limits, voiding intrinsic safety. |
| Wrong T-Class | May exceed substance ignition temperature. |
| Skipping Certification | Risks non-compliance and unsafe equipment. |
How to avoid mistakes:
- Match equipment to IECEx Zone classifications.
- Tighten all Ex d fasteners properly.
- Use only certified Ex glands and accessories.
- Verify Ex i circuit design and barrier compatibility.
- Confirm T-Class matches ignition temperature.
- Always use accredited certification bodies.
IECEx Training and Personnel Competence (CoPC)
The IECEx Certificate of Personnel Competence (CoPC) establishes standardized global competence levels for professionals working in explosive atmospheres.
- Ex 001: Basic knowledge and awareness.
- Ex 004: Maintenance and inspection skills (e.g., flamepaths, barriers).
- Ex 007/008: Overhaul, repair, and maintenance of Ex equipment.
Certified training, such as courses from Extrainings, helps individuals maintain compliance and reduce explosion risks.
Conclusion: Your Path to Ex Compliance
IECEx Zones and Protection Concepts form the foundation of explosion safety. Applying principles—from Ex i energy limitation in Zone 0 to Ex d containment in Zone 1—ensures both safety and regulatory compliance.
For structured, practical learning aligned with IECEx CoPC standards, enroll in our IECEx Certification Training Programs today.
Frequently Asked Questions (FAQs)
The IECEx Certification System is an international scheme that confirms electrical equipment is safe for use in explosive atmospheres containing flammable gases, vapours, or combustible dusts. It streamlines global market access by harmonising technical requirements and reducing the need for duplicate national approvals
While the IECEx Certification System provides a unified global standard for Ex equipment design and installation, local authorities still mandate specific adoption and personnel competence requirements. Companies operating in the Middle East, particularly the UAE, must ensure their equipment selection and documentation meet all local regulations, including those concerning T-Class and EPL selection, to maintain compliance with strict local requirements. This regional focus guarantees the safety principles of the IEC 60079 standards are correctly applied within the operational environment of the Emirates.
Both IECEx and ATEX classify hazardous areas using Zones based on the frequency and duration of explosive atmospheres, but they sit under different frameworks: IECEx is a voluntary international certification system, while ATEX is a legal requirement within the European Union. For engineers and operators, the practical zone definitions (0, 1, 2 for gas and 20, 21, 22 for dust) are technically aligned, making it possible to design systems that satisfy both schemes simultaneously.
Equipment Protection Levels (EPLs) indicate how robustly a device is designed to prevent ignition in a classified zone. Choosing the correct EPL (Ga, Gb, Gc for gas and Da, Db, Dc for dust) ensures the equipment remains safe even when foreseeable faults occur, which is essential for demonstrating compliance during audits and inspections.
Ex d (flameproof) contains any internal explosion and cools escaping gases through flamepaths, Ex e (increased safety) prevents arcs, sparks, and excessive temperatures under normal and specified fault conditions, and Ex i (intrinsic safety) limits energy so that ignition cannot occur. Each method targets a different risk mechanism, so the right protection concept depends on the equipment type, power level, and zone classification.
Zone 0 requires the highest level of protection because an explosive gas atmosphere can be present continuously or for long periods. Intrinsically safe equipment with EPL Ga (such as Ex ia circuits) is typically used in these areas, because energy limitation offers a predictable and verifiable safety margin even if multiple faults occur.
Hazardous area classification defines the zone number, gas or dust group, and sometimes temperature class, which together determine the minimum EPL and protection concept that equipment must meet. When engineers correctly classify areas first, they can then specify Ex d, Ex e, Ex i, Ex p, or Ex t devices with appropriate markings, avoiding over-design, reducing cost, and maintaining compliance.
A marking such as “Ex db IIC T6 Gb” tells you the equipment is certified for explosive atmospheres, uses a flameproof concept with enhanced level “b”, is suitable for the most demanding gas group IIC, has a maximum surface temperature aligned with T6, and provides an EPL of Gb for Zone 1. Reading the code correctly allows inspectors and designers to quickly verify if the device matches the hazardous area classification and process media.
IECEx competence schemes define the knowledge and skills required to design, install, inspect, and maintain Ex equipment safely. Structured training aligned with CoPC units (such as Ex 001, Ex 004, Ex 007/008) helps technicians and engineers apply standards correctly in the field, maintain equipment certification, and reduce the likelihood of ignition-causing errors.
IECEx defines the global standards for explosion protection (like the Zones and Protection Concepts in this guide) and offers the CoPC scheme for personnel competence. Compex is a practical assessment scheme that validates an individual’s hands-on skills in installing and maintaining equipment in hazardous areas, based on those same IEC 60079 standards.
Understanding the specific differences between these two systems—one focused on a global certification and the other on practical skills—is vital for personnel in the UAE, Saudi Arabia, and Qatar. To clarify which qualification you need, review a detailed comparison of Compex vs. IECEx certification.
Typical mistakes include mixing Class/Division and Zone concepts, using incorrect cable glands for Ex d or Ex e, exceeding approved cable lengths in Ex i circuits, and ignoring temperature class limits. These errors can compromise flamepaths, sealing, or energy limitation and may lead to ignition risk, failed inspections, or rejection by certification and insurance bodies.
Accredited IECEx Certification Bodies provide independent testing, documentation review, and factory assessment to confirm compliance with IEC 60079 standards. Partnering with these bodies builds confidence with operators, regulators, and end users, while also shortening time to market and simplifying alignment with ATEX requirements for European projects
