IEC 60079-0 Explained: General Requirements for Ex Equipment

When reviewing electrical equipment for a hazardous area project, the protection marking is only one part of the assessment. The enclosure, materials, temperature limits, construction details and certification documents also need to be consistent with the intended application.

IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements, establishes common requirements for Ex equipment and Ex components. It is used alongside the applicable standard for the equipment's protection concept.

The distinction matters during technical bid evaluation. Two products may both carry an Ex marking, but that does not automatically mean they are suitable for the same gas group, ambient temperature, equipment protection level or installation conditions.

What IEC 60079-0 Covers

IEC 60079-0 addresses general requirements for the construction, testing and marking of equipment intended for use in, or associated with, explosive atmospheres. It provides a common technical basis across different protection concepts rather than defining one complete protection method.

For example, a flameproof enclosure must meet the applicable general requirements as well as the specific requirements of IEC 60079-1. Intrinsically safe equipment is assessed against the applicable requirements of IEC 60079-11 in addition to the relevant general requirements.

This table is a selection of common examples, not a complete list of protection concepts. The applicable standards depend on the equipment design, protection methods and certification basis.

Which Edition of IEC 60079-0 Applies?

The applicable edition should be confirmed before using the standard for a design review, procurement decision or certification assessment.

As of October 2026, the IEC Webstore lists IEC 60079-0:2026, Edition 8, published on 16 June 2026. It replaces the 2017 edition, which was Edition 7. The new edition is a technical revision, so users should not assume that every clause or requirement remains unchanged.

For an actual project, check the edition and amendments specified by the contract, applicable regulations, certification scheme and project documentation. A newly published edition does not, by itself, establish which edition must be used for every existing certificate or project.

Official reference: IEC 60079-0:2026 – IEC Webstore.

Requirements That Matter During Equipment Review

1. Construction and enclosure design

The equipment must be constructed to meet the requirements associated with its certified protection concept. Depending on the design, the assessment may involve enclosure integrity, dimensions, component arrangement, mechanical strength, openings and other construction details.

These details are not interchangeable between protection methods. For instance, a flameproof enclosure relies on design features specific to flameproof protection, while an intrinsically safe circuit is assessed against electrical and energy-limitation requirements. A general review under IEC 60079-0 does not replace those specific assessments.

2. Materials and external surfaces

Material selection can affect the long-term suitability of Ex equipment. Relevant considerations may include mechanical strength, corrosion, thermal behaviour, environmental exposure and the properties of non-metallic external parts.

Electrostatic charging is particularly relevant for some non-metallic surfaces. The suitability of a polymer enclosure therefore cannot be determined from its material name alone. The certified design, intended environment, equipment marking and any stated restrictions need to be considered together.

3. Ingress protection

An IP rating describes protection against access to hazardous parts, solid foreign objects and water under the applicable test conditions. It does not establish explosion protection.

For example, IP66 does not independently demonstrate that an enclosure is suitable for a Zone 1 gas atmosphere or a combustible dust application. The required Ex protection, equipment group, EPL and other project conditions must also be satisfied.

When checking a datasheet, compare the IP requirement with the offered equipment's documentation. Do not use a high IP rating as a substitute for a required Ex certification.

4. Temperature and ambient operating range

Temperature assessment involves more than reading the T-class marking. The maximum surface temperature, ambient temperature range, equipment configuration and applicable certificate conditions all affect suitability.

For gas atmospheres, the familiar temperature classes correspond to the following maximum surface temperatures:

These are the conventional gas temperature-class limits; they should not be used as a substitute for the maximum surface-temperature marking applicable to dust equipment.

Consider an RFQ that requires an Ex luminaire suitable for an ambient temperature up to +55 °C. An offer with the correct gas group and T-class still needs to be checked for its certified ambient range. A product rated only up to +40 °C would not meet that requirement unless the manufacturer's certified documentation supports the required operating conditions.

How to Read the Ex Marking

The marking identifies important characteristics of the equipment. The exact information shown depends on the protection concept and the applicable requirements.

Examples include:

• Ex eb mb IIC Gb
• Ex tb IIIC Db IP66
• Ex ia IIC T4 Ga

These examples illustrate different protection concepts and equipment designations. They are not complete product specifications and should not be treated as interchangeable markings.

When reviewing a real product, verify the full marking against the certificate and the application requirements. Check the gas or dust group, EPL, temperature information where applicable, ambient range, IP rating and any additional restrictions shown on the equipment or its documentation.

Practical Checklist for Procurement and Engineering

For a technical bid evaluation, the useful question is not simply whether a supplier states compliance with IEC 60079-0. The equipment documentation must support the intended application and match the project requirements.

Example: Suppose a supplier offers a junction box with an Ex marking and IP66 enclosure, but the certificate identifies a different model suffix from the one quoted. The correct next step is to clarify the model and confirm the certificate scope. The IP rating alone cannot resolve that discrepancy.

Likewise, a certificate reference should not be accepted solely because it appears on a datasheet. Verify the certificate through the relevant certification scheme or issuing body and confirm that the offered configuration falls within its scope.

Equipment Certificates and Components

IEC 60079-0 applies to Ex equipment and Ex components, but these terms should not be treated as equivalent in procurement.

An Ex component may be intended for incorporation into completed equipment and may require additional assessment before the final assembly can be used. A component certificate does not automatically establish that the finished product is certified for the intended hazardous area.

When a supplier offers a certified component as part of an assembly, check the certificate type, any schedule of limitations and the requirements for evaluating the completed equipment. The final assessment depends on the design and applicable certification route.

What IEC 60079-0 Does Not Replace

IEC 60079-0 is not a standalone guide to every stage of hazardous area engineering. Other standards address specific tasks across the equipment and installation lifecycle.

The standards have different scopes. Selecting equipment, classifying a hazardous area and inspecting an installed system are related activities, but they are not the same assessment.

Common Mistakes in an Ex Equipment Review

• Accepting an IP rating as proof of Ex suitability. IP protection and explosion protection address different requirements.
• Checking only the T-class. The ambient temperature range and other certificate restrictions may affect suitability.
• Assuming IEC 60079-0 covers the complete protection concept. The applicable protection-specific standard must also be considered.
• Ignoring the exact model designation. The offered model and configuration must be consistent with the supporting certification documents.
• Using an outdated edition without checking the project basis. Confirm which edition and amendments apply to the relevant design or certification decision.
• Overlooking conditions for safe use. Restrictions identified in the certification documents must be evaluated before the equipment is accepted for the intended application.

Related IEC 60079 Guides

For more detail on specific protection concepts and lifecycle activities, see:

• IEC 60079 Series Explained: A Complete Guide to Explosion Protection Standards
• IEC 60079-11 Explained: Intrinsic Safety
• IEC 60079-14 Explained: Electrical Installation in Explosive Atmospheres
• IEC 60079-17 Explained: Inspection and Maintenance
• IEC 60079-19 Explained: Equipment Repair, Overhaul and Reclamation
• IEC 60079-31 Explained: Protection by Enclosure for Dust

References

• IEC 60079-0:2026 – Explosive atmospheres, Part 0: Equipment – General requirements
• IEC 60079-0:2017 – Previous edition
• IECEx – International Certification System for Equipment Used in Explosive Atmospheres

This article is a practical introduction to the scope and application of IEC 60079-0. It does not reproduce the standard or replace the applicable standard edition, certificate, manufacturer's instructions, project specification or regulatory requirements. Confirm the applicable requirements before making a design, procurement or compliance decision.