SC 31J - Classification of hazardous areas and installation requirements

IEC 60079:2024 contains the specific requirements for the design of electrical systems, selection, installation and the required initial inspection of electrical installations of Ex Equipment in, or associated with, explosive atmospheres including requirements for documentation and personnel competency.
These requirements are in addition to the requirements for installations in non-hazardous areas.
This document applies to all electrical Ex Equipment including fixed, transportable, portable and personal, and installations, permanent or temporary.
This document does not apply to:
• electrical installations in mines susceptible to firedamp;
• inherently explosive situations and dust from explosives or pyrophoric substances (for example explosives manufacturing and processing);
• rooms used for medical purposes;
• electrical installations in areas where the hazard is due to flammable mist; and
• installation of non-electrical Ex Equipment (unless being part of an equipment assembly according IEC TS 60079-46).
No account is taken in this document of the toxic hazards that are associated with flammable gases, liquids and dusts in concentrations that are usually very much less than the lower flammable limit. In locations where personnel could be exposed to potentially toxic concentrations of flammable material, appropriate precautions are necessary. Such precautions are outside the scope of this document.
This sixth edition cancels and replaces the fifth edition published in 2013. This edition constitutes a technical revision. Edition 6 is a major restructure and introduces a number of technical changes from the previous edition (2013), see Table 1 of the foreword for detailed information.

IEC 60079-17:2023 applies to users and covers only those factors directly related to the inspection and maintenance of electrical installations specifically designed for hazardous areas, where the hazard is caused by explosive atmospheres.
It does not include:
- other fundamental installation and inspection requirements for electrical installations;
- the verification of electrical equipment;
- protection or ventilation of rooms;
- gas detection systems;
- the repair, overhaul and reclamation of explosion protected equipment (see IEC 60079-19).
While this document does not include inspection of safety devices such as used in ventilated rooms (see IEC 60079-13), it does include the requirements for inspection and maintenance of individual items of equipment that will be part of such systems, for example motors or sensors. This document supplements the requirements for inspection and testing in non-hazardous areas in IEC 60364-6. This document is intended to be applied where there is a risk due to the potential presence of explosive gas or dust mixtures with air or combustible dust layers under normal atmospheric conditions. It does not apply to:
- underground mining areas,
- dusts of explosives,
- pyrophoric substances.
This sixth edition cancels and replaces the fifth edition published in 2013. This edition constitutes a technical revision.

IEC 60079-48:2023, which is a Technical Specification, provides guidance for an owner or operator for the use of portable or personal electronic equipment to be used in hazardous areas requiring Equipment Protection Level (EPL) Gb, Gc, Db, or Dc that are not otherwise commercially available with a certificate.
This document does not apply to:
• equipment that is electrically connected to fixed equipment or fixed wiring during use in the hazardous area, for example a lead light connected to the premises wiring system by a plug and socket,
• portable or personal equipment with a certificate for use in a hazardous area,
• transportable equipment,
• portable or personal equipment used in Group I applications,
• battery powered tools, such as drills and saws,
• portable or personal equipment used in areas requiring EPL Ga or Da equipment, or,
• medical devices.
This document does not address other considerations involving the use of portable or personal electronic equipment for other aspects of safety, for example, creation of a distraction from important work tasks, radio frequency interference with measurement and control equipment, or medical issues.
This document supplements the guidance in IEC 60079-14 regarding the use of personal or portable equipment without a certificate for use in hazardous areas.

IEC 60079-10-1:2020 is concerned with the classification of areas where flammable gas or vapour hazards may arise and may then be used as a basis to support the proper design, construction, operation and maintenance of equipment for use in hazardous areas.
It is intended to be applied where there may be an ignition hazard due to the presence of flammable gas or vapour, mixed with air, but it does not apply to:
a) mines susceptible to firedamp;
b) the processing and manufacture of explosives;
c) catastrophic failures or rare malfunctions which are beyond the concept of normality dealt with in this standard;
d) rooms used for medical purposes;
e) domestic premises;
f) where a hazard may arise due to the presence of combustible dusts or combustible flyings but the principles may be used in assessment of a hybrid mixture.
Flammable mists may form or be present at the same time as flammable vapour. In such case the strict application of the details in this document may not be appropriate. Flammable mists may also form when liquids not considered to be a hazard due to the high flash point are released under pressure. In these cases the classifications and details given in this document do not apply.
For the purpose of this document, an area is a three-dimensional region or space.
Atmospheric conditions include variations above and below reference levels of 101,3 kPa (1 013 mbar) and 20 °C (293 K), provided that the variations have a negligible effect on the explosion properties of the flammable substances.
In any site, irrespective of size, there may be numerous sources of ignition apart from those associated with equipment. Appropriate precautions will be necessary to ensure safety in this context. This standard is applicable with judgement for other ignition sources but in some applications other safeguards may also need to be considered. E.g. larger distances may apply for naked flames when considering hot work permits.
This document does not take into account the consequences of ignition of an explosive atmosphere except where a zone is so small that if ignition did occur it would have negligible consequences.
This third edition of IEC 60079-10-1 cancels and replaces the second edition, published in 2015, and constitutes a technical revision, see foreword for further details.

IEC 60079-19:2019 gives instructions, principally of a technical nature, on the repair, overhaul, reclamation and modification of equipment designed for use in explosive atmospheres; it is not applicable to maintenance, other than when repair and overhaul cannot be disassociated from maintenance, neither does it give advice on cable entry systems which may require a renewal when the equipment is re-installed.
This fourth edition cancels and replaces the third edition published in 2010 together with Amendment 1:2015. This edition constitutes a technical revision.
The significance of the changes between IEC 60079-19, Edition 3 (2010), including Amendment 1 (2015), and IEC 60079-19, Edition 4 (2019) are defined in the foreword and cover minor and editorial changes, extension, and major technical changes.

IEC 60079-13:2017 gives requirements for the design, construction, assessment, verification and marking of rooms used to protect internal equipment:
– located in a Zone 1 or Zone 2 or Zone 21 or Zone 22 explosive atmosphere without an internal source of gas/vapour release and protected by pressurization;
– located in a Zone 2 explosive atmosphere with or without an internal source of gas/vapour release and protected by artificial ventilation;
– located in a non-hazardous area, containing an internal source of gas/vapour release and protected by artificial ventilation;
– located in a Zone 1 or Zone 2 or Zone 21 or Zone 22 explosive atmosphere containing an internal source of gas/vapour release and protected by both pressurization and artificial ventilation.
The term "room" used in this document includes single rooms, multiple rooms, a complete building or a room contained within a building. A room is intended to facilitate the entry of personnel and includes inlet and outlet ducts. An acoustic hood and other like enclosures designed to permit the entry of personnel can be considered as a room.
This document also includes requirements related safety devices and controls necessary to ensure that artificial ventilation, purging and pressurization is established and maintained.
A room assembled or constructed on site, can be either on land or off-shore. The room is primarily intended for installation by an end-user but could be constructed and assessed at a manufacturer’s facility, where the final construction such as ducting can be completed on site.
This document does not specify the methods that may be required to ensure adequate air quality for personnel with regard to toxicity and temperature within the room. National or other regulations and requirements may exist to ensure the safety of personnel in this regard.
This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) modification of the title of this document to include artificially ventilated room "v" in addition to pressurized room "p";
b) addition of types of protection "pb", "pc", and "vc" and removal of types of protection "px", "py", "pz" and "pv";
c) definition of the differences between pressurization and artificial ventilation types of protection;
d) removal of protection of rooms with an inert gas or a flammable gas from the scope of this document;
e) addition of an informative annex to include examples of applications where types of protection pressurization or artificial ventilation or pressurization and artificial ventilation can be used and associated guidelines.

IEC 60079-10-1:2015 is concerned with the classification of areas where flammable gas or vapour hazards may arise and may then be used as a basis to support the proper selection and installation of equipment for use in hazardous areas. It is intended to be applied where there may be an ignition hazard due to the presence of flammable gas or vapour, mixed with air, but it does not apply to:
- mines susceptible to firedamp;
- the processing and manufacture of explosives;
- catastrophic failures or rare malfunctions which are beyond the concept of abnormality dealt with in this standard (see 3.7.3 and 3.7.4);
- rooms used for medical purposes;
- commercial and industrial applications where only low pressure fuel gas is used for appliances e.g. for cooking, water heating and similar uses, where the installation is compliant with relevant gas codes;
- domestic premises;
- where a hazard may arise due to the presence of combustible dusts or combustible flyings but the principles may be used in assessment of a hybrid mixture (refer also IEC 60079-10-2). This second edition of IEC 60079-10-1 cancels and replaces the first edition, published in 2008, and constitutes a technical revision. The significant technical changes with respect to the previous edition are identified in the Foreward of the document. Keywords: ignition hazards, flammable gas or vapour, risk of explosions

Defines the distribution line message specification (DLMS) within the OSI application layer.

This publication is of high relevance for Smart Grid.

IEC 60079-10-2:2015 is concerned with the identification and classification of areas where explosive dust atmospheres and combustible dust layers are present, in order to permit the proper assessment of ignition sources in such areas. In this standard, explosive dust atmospheres and combustible dust layers are treated separately. In Clause 4, area classification for explosive dusts clouds is described, with dust layers acting as one of the possible sources of release. In Clause 7 other general considerations for dust layers are described. The examples in this standard are based on a system of effective housekeeping being implemented in the plant to prevent dust layers from accumulating. Where effective housekeeping is not present, the area classification includes the possible formation of explosive dust clouds from dust layers. The principles of this standard can also be followed when combustible fibres or flyings might cause a hazard. This standard is intended to be applied where there can be a risk due to the presence of explosive dust atmospheres or combustible dust layers under normal atmospheric conditions. Please refer to the foreword of the document for a detailed listing of the significant technical changes from the previous edition. Keywords: explosive dust atmospheres, combustible dust layers, ignition hazards

IEC 60079-14:2013 contains the specific requirements for the design, selection, erection and initial inspection of electrical installations in, or associated with, explosive atmospheres. Where the equipment is required to meet other environmental conditions, for example, protection against ingress of water and resistance to corrosion, additional protection requirements may be necessary. The requirements of this standard apply only to the use of equipment under standard atmospheric conditions as defined in IEC 60079-0. For other conditions, additional precautions may be necessary, and the equipment should be certified for these other conditions. For example, most flammable materials and many materials which are normally regarded as non-flammable might burn vigorously under conditions of oxygen enrichment. These requirements are in addition to the requirements for installations in non-hazardous areas. This standard applies to all electrical equipment including fixed, portable, transportable and personal, and installations, permanent or temporary. No account is taken in this Standard of the toxic risks that are associated with flammable gases, liquids and dusts in concentrations that are usually very much less than the lower explosive limit. In locations where personnel may be exposed to potentially toxic concentrations of flammable material, appropriate precautions should be taken. Such precautions are outside the scope of this Standard. This fifth edition cancels and replaces the fourth edition published in 2007. This edition constitutes a technical revision. Refer to the document's Foreward for a listing of the specific revisions and additional Notes. Key words: requirements for the design, selection, erection and initial inspection of electrical installations in explosive atmospheres.
The contents of the corrigendum of January 2016, the interpretation sheet 1 of February 2017 and March 2020 have been included in this copy.

IEC 60079-17:2013 applies to users and covers factors directly related to the inspection and maintenance of electrical installations within hazardous areas only, where the hazard may be caused by flammable gases, vapours, mists, dusts, fibres or flyings. It does not include:
- other fundamental installation and inspection requirements for electrical installations;
- the verification of electrical equipment;
- the repair and reclamation of explosion protected equipment (see IEC 60079-19). This standard supplements the requirements of IEC 60364-6. In the case of dusts, fibres or flyings the level of housekeeping may influence the inspection and maintenance requirements. This standard is intended to be applied where there can be a risk due to the presence of explosive gas or dust mixtures with air or combustible dust layers under normal atmospheric conditions. It does not apply to:
- underground mining areas,
- dusts of explosives that do not require atmospheric oxygen for combustion,
- pyrophoric substances. This fifth edition cancels and replaces the fourth edition published in 2007 and constitutes a technical revision. The significant technical changes with respect to the previous edition are as follows:
- Equipment specific inspection tables for luminaires, heating systems and motors have been added into Annex A to supplement the general protection concept tables;
- Document has been updated to complement the changes made to IEC 60079-14 for initial inspection. Keywords: inspection and maintenance of electrical installations within hazardous area, flammable gases, vapours, mists, dusts, fibres or flyings
This publication is to be read in conjunction with IEC 60364-6:2006.

IEC 60079-19:2010 gives instructions, principally of a technical nature, on the repair, overhaul, reclamation and modification of equipment designed for use in explosive atmospheres; it is not applicable to maintenance, other than when repair and overhaul cannot be disassociated from maintenance, neither does it give advice on cable entry systems which may require a renewal when the equipment is re-installed. The significant technical changes with respect to the previous edition are:
- inclusion of specific Group I requirements;
- inclusion of offshore requirements.

IEC 60079-10-2:2009 is concerned with the identification and classification of areas where explosive dust atmospheres and combustible dust layers are present, in order to permit the proper assessment of ignition sources in such areas. The principles of this standard can also be followed when combustible fibres or flyings may cause a hazard. This standard is intended to be applied where there can be a risk due to the presence of explosive dust atmospheres or combustible dust layers under normal atmospheric conditions. This first edition of IEC 60079-10-2 cancels and replaces the first edition of IEC 61241-10 published in 2004. The significant technical changes with respect to IEC 61241-10 are:
- the hazards presented by dust have been clarified;
- dust groups have been introduced;
- Annex D explaining Equipment Protection Levels (EPLs) has been introduced;
- 1 m of usual extent of zone 22 beyond zone 21 has been expanded to 3 m.

IEC 60079-10-1:2008 is concerned with the classification of areas where flammable gas or vapour or mist hazards may arise and may then be used as a basis to support the proper selection and installation of equipment for use in a hazardous area. It is intended to be applied where there may be an ignition hazard due to the presence of flammable gas or vapour, mixed with air under normal atmospheric conditions, but it does not apply to
a) mines susceptible to firedamp;
b) the processing and manufacture of explosives;
c) areas where a hazard may arise due to the presence of combustible dusts or fibres;
d) catastrophic failures which are beyond the concept of abnormality;
e) rommos used for medial purposes;
f) domestic premises.
This first edition of IEC 60079-10-1 cancels and replaces the fourth edition of IEC 60079-10, published in 2002, and constitutes a technical revision. The significant technical changes with respect to the previous edition are:
- introduction of Annex D which deals with explosion hazard from flammable mists generated by the release under pressure of high flash point liquids;
- introduction of Clause A.3 (release rate) which gives thermodynamic equations for release rate with a number of examples for estimating release rate of fluids and gases.

This part of IEC 60079 contains the specific requirements for the design, selection and erection of electrical installations in hazardous areas associated with explosive atmospheres. Where the equipment is required to meet other environmental conditions, for example, protection against ingress of water and resistance to corrosion, additional methods of protection may be necessary. The method used should not adversely affect the integrity of the enclosure. The requirements of this standard apply only to the use of equipment under normal or near normal atmospheric conditions. The significant technical changes with respect to the previous edition are: Equipment Protection Levels (EPLs) have been introduced and are explained in the new Annex I and dust requirements included from IEC 61241 14, Ed. 1.0.

This part of IEC 60079 applies to users and covers factors directly related to the inspection and maintenance of electrical installations within hazardous areas only, where the hazard may be caused by flammable gases, vapours, mists, dusts, fibres or flyings. It does not apply to underground mining areas, areas where a risk can arise due to the presence of hybrid mixtures, dusts of explosives that do not require atmospheric oxygen for combustion, and pyrophoric substances. The significant technical changes with respect to the previous edition are as follows: Additional requirements for inspection and maintenance of electrical installations for combustible dusts and Equipment Protection Levels have been introduced and are explained in the new Annex C.

This part of IEC 60079 gives instructions, principally of a technical nature, on the repair, overhaul, reclamation and modification of a certified equipment designed for use in explosive atmospheres; it is not applicable to maintenance, other than when repair and overhaul cannot be disassociated from maintenance, neither does it give advice on cable entry systems which may require renewal when the equipment is re-installed.

This part of IEC 60079 contains the specific requirements for the design, selection and erection of electrical installations in explosive gas atmospheres. These requirements are in addition to the requirements for installations in non-hazardous areas. This standard applies to all electrical equipment and installations in hazardous areas whether permanent, temporary, portable, transportable or hand-held. It applies to installations at all voltages. This standard does not apply to - electrical installations in mines susceptible to firedamp; - electrical installations in areas where the hazard is due to combustible dusts or fibres; - inherently explosive situations, for example explosives manufacturing and processing; - rooms used for medical purposes.

This International Standard is intended to be applied by users, and covers factors directly related to the inspection and maintenance of electrical installations within hazardous areas only. It does not include conventional requirements for electrical installations, nor the testing and certification of electrical apparatus. It does not cover Group I apparatus (applications for mines susceptible to firedamp). It does not cover the alternative of "Continuous supervision by skilled personnel".

Contains the specific requirements for the design, selection and erection of electrical installations in explosive gas atmospheres.

This International Standard is intended to be applied by users, and covers factors directly related to the inspection and maintenance of electrical installations within hazardous areas only. It does not include conventional requirements fo relectrical installations, nor the testing and certification of electrical apparatus. It does not cover Group I apparatus (applications fo rmines susceptible to firedamp). It does not cover the alternative of "Continuous supervision by skilled personnel".

Is concerned with the classification of hazardous areas where flammable gas or vapour risks may arise, in order to permit the proper selection and installation of apparatus for use in such hazardous areas. The contents of the corrigendum of May 1996 have been included in this copy.

This part of IEC 60079 gives instructions, principally of a technical nature, on the repair, overhaul, reclamation and modification of a certified equipment designed for use in explosive atmospheres; it is not applicable to maintenance, other than when repair and overhaul cannot be disassociated from maintenance, neither does it give advice on cable entry systems which may require renewal when the equipment is re-installed.

Specifies general requirements, additional to those required for basic electrical safety, for the selection of electrical apparatus and instruments and associated equipment, and for the installation of electrical apparatus to ensure safe use in areas where combustible dust may be present in quantities which could lead to a fire or explosion hazard. The application of electrical apparatus in atmospheres which may contain explosive gas as well as combustible dust, whether simultaneously or separately, requires additional protective measures.

Deals with the classification of areas where explosive dust/air mixtures and combustible dust layers are present, in order to permit the proper selection of equipment for use in such areas. The principles of the standard can also be followed when combustible fibres or flyings may cause a hazard. To be applied where there can be a risk due to the presence of explosive dust/air mixtures or combustible dust layers under normal atmospheric conditions.

Is concerned with the classification of hazardous areas where flammable gas or vapour risks may arise, in order to permit the proper selection and installation of apparatus for use in such hazardous areas.