ATEX and IECEx Standards for hazardous areas explained

Just received a question again: what is the difference here? ATEX version is cheaper…

So time again to GO more into details about ATEX / IECEX.

Here is an explanation of ATEX and IECEx standards, markings, classification, directive and different zones.

ATEX products are differentiated from standard products by their markings, most noticeably the recognised Ex symbol.

Under The ATEX and IECEx schemes, products are classified and marked to show the areas in which they can be used, and the level of protection employed.

Ex products classifications:


IECEx – ia IIC T4 Ga


For current ATEX/IECEx equipment markings the protection concepts are:

ATEX – II 1 G where: Equipment Group II is for use in all other areas other than mines.

Category 1 for use Zones 0, 1 and 2 for gases/vapours.

Environment G for use in hazardous gas, vapour or mist environments.

IECEx – ia IIC T4 Ga

Type of Protection ia is Intrinsic Safety.

Gas Group IIC is gas, vapour or mist, except in coal mines.

Temperature Class T4 is up to 135 C (248 F)

Equipment Protection Level Ga – suitable for use in Zones 0, 1, 2.

Actual markings form part of the labels affixed to the ATEX/IECEx unit.

In the European Union (EU) and USA, all electrical/electronic or mechanical equipment used in explosive, or potentially explosive atmospheres, must be manufactured to strict standards to ensure that the possibility of the equipment to cause explosion, in both normal and abnormal operation, is minimised. This includes equipment being designed with appropriate safety devices and protection systems, and being manufactured and tested under controlled conditions. Compliance has to be verified by recognised third party professional bodies.

In the EU, the ATEX Directive defines technical and management systems requirements for compliance. In the USA and other international regions, similar requirements are specified by the IECEx scheme.

There is an accelerating growth rate for ATEX/IECEx approvals, principally driven by the upward demand for energy and growth amongst developing and emerging economies, and their increased awareness of the need for “Proof of Compliance” with minimum safety standards.

Explosive Atmospheres

Under ATEX and IECEx, an explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapours, mist or dust in which, after ignition has occurred, combustion spreads to the entire unburned mixture.

Atmospheric conditions are commonly referred to as ambient temperatures and pressures. That is to say temperatures of –20°C to 40°C and pressures of 0.8 to 1.1 bar.

Potentially explosive atmospheres can typically be found in industry sectors as:

– On shore and offshore oil and gas rigs

– Petrochemical refineries

– Fuel distribution depots

– Oil and gas pipeline installation, repair and maintenance

– Chemical and pharmaceutical industry

– Mining

– Building, construction and civil engineering in hazardous environments

– Producers and users of solvents, paints, varnishes and other flammable liquids

– Printing and textiles

– Food manufacturers, wood processors, grain handling & storage – where dusts are created

– Engineering where dusts are created from machining, grinding and sanding

Organisations that operate within these and other industry sectors are obliged to assess their business activities to identify potential explosive atmospheres and to implement control measures to reduce the possibility of inadvertent explosion. Measures include using only Ex approved equipment. In the EU, this is a legal obligation.


ATEX is The European Regulatory Framework for Manufacture, Installation and Use of Equipment in Explosive Atmospheres (denoted by Ex).

It came into force in 2003, and was enacted in the UK by statutory Instrument (SI) 2002: 2776. It was called DSEAR (The Dangerous Substances and Explosive Atmospheres Regulations of 2002), and implemented both the ATEX and the Chemical Agents Directive (98/24/EC).

The name ATEX comes from the French title of the 94/9/EC EU Directive: Appareils destinés à être utilisés en ATmosphères EXplosibles, which is concerned with explosive atmospheres.

There are actually two EU directives that relate to potentially explosive atmospheres and although the subjects they deal with are different, they have links that allow both of them to work together:

1999/92/EC – Concerned with Classification of Hazardous Areas and the correct selection, installation, inspection and maintenance of Ex Equipment;

94/9/EC – Concerned with the manufacture and sale of Ex Equipment

IECEx is the International Electrotechnical Commission Scheme for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres.

ATEX is driven by EU law whereas IECEx is a voluntary certification scheme. Both however, provide an accepted means of proving compliance with IEC standards.

The difference between ATEX and IECEx is initially that ATEX is only valid in the EU and IECEx accepted globally.

EU Directives

EU Directive 1999/92/EC, also known as the ATEX Directive, and commonly referred to as the Workplace Directive, sets out the responsibilities of the employers (Not manufacturers) for implementing minimum health and safety requirements for the protection of employees at risk from explosive atmospheres in the workplace.

It requires that where the risk assessments identify workplaces as likely to be hazardous areas or explosive atmospheres, that the areas are classified into zones:

Zone 0 – where an explosive atmosphere is present continuously or for long periods;

Zone 1 – where an explosive atmosphere is likely during normal operations;

Zone 2 – where an explosive atmosphere is unlikely, but where it does occur, that it will only exist for a short period.

These are for gases/vapours. There are similar zones 20, 21 and 22 for dusts.

Once zones have been identified and classified, any equipment with a potential ignition source (electrical and non.electrical) must comply with the EU Directive EU 2014/34/EU (which replace the previous Directive 94/9/EC in April 2016) relating to each of the zone classifications in which it is being used.

The Directive also specifies other controls for working in the various zones. These include:

▪ The identification of zones with Ex signs at all points of entry;

▪ The use of a Permit to Work system within Ex zones;

▪ Provision of suitable PPE, including anti-static clothing;

▪ Provision of hazardous area awareness training;

▪ Maintaining records relating to the risk assessment/zone classification, inspections, training and other pertinent records.

Technical Standards

Both ATEX and IECEx both require compliance with the same technical standards, so in terms of technical content, there is basically no difference. Only visible difference is in many cases the marking on the device.

IEC (The International Electrotechnical Commission) Standard IEC 60079 is a suite of Standards that cover a wide standards relating to different types of equipment and protection measures in explosive atmospheres.

Few applicable technical standards:

IEC 60079-0 Explosive Atmospheres – Part 0: Equipment – General Requirements
This Standard specifies the general requirements for construction, testing and marking of electrical equipment and Ex Components intended for use in explosive atmospheres IEC 60079-0 Explosive

Atmospheres – Part 11: Equipment by Intrinsic Safety
This Standard specifies the construction and testing of intrinsically safe apparatus intended for use in an explosive atmosphere and for associated apparatus, which is intended for connection to intrinsically safe circuits which enter such atmospheres. This type of protection is applicable to electrical equipment in which the electrical circuits themselves are incapable of causing an explosion in the surrounding explosive atmospheres.

IEC 60079-0 Explosive Atmospheres – Part 25: Intrinsically safe Electrical Systems

This Standard contains the specific requirements for construction and assessment of intrinsically safe electrical systems, type of protection “i”, intended for use, as a whole or in part, in locations in which the use of Group I, II or III apparatus is required. This standard supplements and modifies the general requirements of IEC 60079-0 and the intrinsic safety standard IEC 60079-11.

“Intrinsic Safety” is a protection technique applied to electrical equipment and wiring for hazardous locations. The technique is based on limiting electrical and thermal energy to a level below that which can cause ignition of a specific hazardous atmospheric mixture

ISO/IEC 80079-34:2011

ISO/IEC 80079-34:2011 specifies particular requirements and information for establishing and maintaining a quality system to manufacture Ex Category 1 and Category 2 equipment including protective systems in accordance with the Ex certificate. It is compatible with the objectives of ISO 9001:2015.

Compliance with this standard is required before ATEX/IECEx can be manufactured for sale into the market place.

Source: straightpoint

So it is a legal, technical but commercial differentiation too. There is no direct ‘=’.

Keep up good work!



  1. Congrats for the content, is very clear and simple.
    I’m typing from Brazil, I work at MSA, a big American Company that manufactures Gas and Flames Detectors, and sometimes we face some difficulties to identify the mark on instrument.

    Could you send me a table explaining the meaning of each part in the ATEX and IECEx marking?

    Best regards.

  2. Arpad, very clear article!
    I have worked about 30 yars for TOTAl E&P, in my country Argentina, and doing some missions in different facilities over the world for the Group.
    Now I am retired from the formal activities, and soending time as free lancer Electrica safety trainer.

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