IEC 60079‑14: Safety of electrical installations in explosive atmospheres

The reference standard for the electrical equipment of machinery is IEC 60204‑1. This standard also applies when machinery is installed, even partially, in areas where there is a risk of a potentially explosive atmosphere (classified ATEX areas). However, in such cases, the requirements of IEC 60204‑1 must be supplemented with those specified in IEC 60079‑14.

When an industrial installation operates in the presence of flammable gases, vapours or combustible dusts, explosion risk becomes a central safety issue. The standard IEC 60079‑14 has been developed precisely to reduce the probability that electrical equipment may act as an ignition source. For this reason, it defines specific requirements for system design, equipment selection, installation methods and initial inspection prior to commissioning, as well as for technical documentation and personnel competence.

This standard is part of the IEC 60079 series, “Explosive atmospheres”, and represents an international reference for all industrial sectors classified as ATEX. Over the years, IEC 60079‑14 has undergone several revisions. The 2024 edition replaces the previous 2013 version and introduces several changes that make the standard clearer, more comprehensive and better structured. In particular, the 2024 edition:

• explains more explicitly the possible sources of ignition that an electrical installation must avoid;
• provides clearer guidance on equipment selection based on the type of hazard;
• introduces more detailed requirements for documentation, checks and initial verification;
• places greater emphasis on the competence of personnel involved in the design, installation and verification of electrical installations.

A fundamental concept addressed by the standard is the classification of hazardous areas. Areas are divided into zones based on the frequency and duration of the presence of an explosive atmosphere. This classification plays a key role, as it allows the evaluation of the level of risk associated with each area and, consequently, the selection of electrical equipment with an appropriate level of protection.

Each classified zone is associated with an Equipment Protection Level (EPL), which defines the minimum protection level required for electrical equipment intended to operate in that area. As the probability of the presence of an explosive atmosphere increases, a higher level of equipment protection is required. Based on zone classification, the following distinctions apply:

• EPL Ga and Da, intended for Zones 0 and 20, where the explosive atmosphere is present continuously or for long periods;
• EPL Gb and Db, intended for Zones 1 and 21, where the explosive atmosphere is likely to occur during normal operation;
• EPL Gc and Dc, intended for Zones 2 and 22, where the presence of an explosive atmosphere is unlikely and limited in duration.

Another key element is the design of the electrical installation in areas with explosion risk. The standard defines the criteria to be applied from the earliest design stages, ensuring that no component of the installation can constitute an ignition source under normal operating conditions or foreseeable faults.

IEC 60079‑14 specifies that the design must prevent ignition caused by electrical sparks, hot surfaces, stray currents and electrostatic charges. To this end, the standard provides guidance on grounding and equipotential bonding, protection against electrostatic charge accumulation, and the use of wiring systems suitable for the area conditions.

The standard underlines that the safety of an installation cannot be ensured only by individual Ex equipment but depends on the overall behaviour of the electrical system and the interaction between power sources, protection devices, cables, machinery and auxiliary systems.

One of the central aspects of IEC 60079‑14 concerns the criteria for selecting electrical equipment and the installation methods in environments with explosive atmosphere risk.

Chapters 7 and 8 of the standard define the relationship between area classification, equipment characteristics and installation execution, with the aim of ensuring that the electrical installation does not present a potential source of ignition. Selection and installation cannot be considered independent phases. Even properly certified equipment may lose its Ex suitability if installed incorrectly, while correct installation practices cannot compensate for inappropriate equipment selection. For this reason, the standard requires both phases to be addressed in a coordinated, documented and verifiable manner, forming an essential part of the explosion risk prevention process in electrical installations.

Selection of Ex equipment must begin with an analysis of the area in which it will be installed. Based on the classified zone, the standard requires the equipment to be suitable with respect to:

• equipment protection level (EPL);
• group of gases or dusts present;
• temperature class;
• applied Ex type of protection.

The standard clarifies that equipment selection must also consider environmental and installation conditions, such as ambient temperature, pollution degree, presence of dust, humidity, vibration and solar radiation. Attention is also given to the selection of cables, cable glands and entry devices, which must be compatible both with the equipment type of protection and with the expected operating conditions.

Once suitable equipment has been selected, IEC 60079‑14 requires that installation shall not adversely affect the Ex protection characteristics. Therefore, the standard defines the main installation requirements for electrical systems in classified areas. In particular, it requires that:

• equipment be installed in accordance with the manufacturer’s documentation;
• cables and wiring systems be routed and secured to prevent mechanical damage, excessive stress or conditions that could reduce the degree of protection;
• cable entry devices and other fittings ensure an adequate degree of protection;
• equipotential bonding and grounding be implemented to prevent potential differences and electrostatic charge accumulation.

Finally, Chapter 9 and the related annexes address the subject of initial inspection of the installation, which must be carried out at the end of construction work and before the electrical system in the classified area is put into service. The purpose of the inspection is to verify that Ex equipment selection and installation have been performed correctly and in compliance with the requirements of the standard, the manufacturer’s documentation and the specific conditions of the area.

In addition to technical aspects, IEC 60079‑14 places particular importance on system documentation and personnel competence. The standard requires that design, selection, installation and initial inspection activities be adequately documented, ensuring traceability of the technical decisions made and verifiability of compliance with safety requirements.

Furthermore, the standard specifies that these activities must be carried out exclusively by competent personnel with specific training in explosive atmospheres and Ex protection methods. Competence must not only be declared, but also demonstrable and up to date.