EN IEC 60079-26:2024

SLOVENSKI STANDARD
01-september-2024
Eksplozivne atmosfere - 26. del: Oprema z ločevalnimi elementi ali kombinirano
stopnjo zaščite (IEC 60079-26:2021)
Explosive atmospheres - Part 26: Equipment with Separation Elements or combined
Levels of Protection (IEC 60079-26:2021)
Explosionsgefährdete Bereiche - Teil 26: Betriebsmittel mit Trennelementen oder
kombinierten Zündschutzarten (IEC 60079-26:2021)
Atmosphères explosives - Partie 26: Appareil avec éléments de séparation ou niveaux
de protection combinés (IEC 60079-26:2021)
Ta slovenski standard je istoveten z: EN IEC 60079-26:2024
ICS:
29.260.20 Električni aparati za Electrical apparatus for
eksplozivna ozračja explosive atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60079-26

NORME EUROPÉENNE
EUROPÄISCHE NORM April 2024
ICS 29.260.20 Supersedes EN 60079-26:2015
English Version
Explosive atmospheres - Part 26: Equipment with Separation
Elements or combined Levels of Protection
(IEC 60079-26:2021)
Atmosphères explosives - Partie 26: Appareil avec Explosionsgefährdete Bereiche - Teil 26: Betriebsmittel mit
éléments de séparation ou niveaux de protection combinés Trennelementen oder kombinierten Zündschutzarten
(IEC 60079-26:2021) (IEC 60079-26:2021)
This European Standard was approved by CENELEC on 2021-04-01. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60079-26:2024 E

European foreword
The text of document 31/1562/FDIS, future edition 4 of IEC 60079-26, prepared by IEC/TC 31
"Equipment for explosive atmospheres" was submitted to the IEC-CENELEC parallel vote and
approved by CENELEC as EN IEC 60079-26:2024.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2024-10-26
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-04-26
document have to be withdrawn
This document supersedes EN 60079-26:2015 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CENELEC by the
European Commission. The Standing Committee of the EFTA States subsequently approves these
requests for its Member States.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60079-26:2021 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60079-14 NOTE Approved as EN 60079-14
ISO 80079-37 NOTE Approved as EN ISO 80079-37
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60079-0 - Explosive atmospheres - Part 0: Equipment EN IEC 60079-0 -
- General requirements
IEC 60079-1 - Explosive atmospheres - Part 1: Equipment EN 60079-1 -
protection by flameproof enclosures "d"
IEC 60079-11 - Explosive atmospheres - Part 11: EN 60079-11 -
Equipment protection by intrinsic safety "i"
IEC 60079-31 - Explosive atmospheres - Part 31: EN 60079-31 -
Equipment dust ignition protection by
enclosure "t"
IEC/TS 60079-40 - Explosive atmospheres - Part 40: - -
Requirements for process sealing between
flammable process fluids and electrical
systems
IEC 60529 - Degrees of protection provided by EN 60529 -
enclosures (IP Code)
IEC 60695-11-10 - Fire hazard testing - Part 11-10: Test EN 60695-11-10 -
flames - 50 W horizontal and vertical flame
test methods
ISO 80079-36 - Explosive atmospheres - Part 36: Non- EN ISO 80079-36 -
electrical equipment for explosive
atmospheres - Basic method and
requirements
IEC 60079-26 ®
Edition 4.0 2021-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Explosive atmospheres –
Part 26: Equipment with Separation Elements or combined Levels of Protection

Atmosphères explosives –
Partie 26: Appareil avec éléments de séparation ou niveaux de protection

combinés
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.260.20 ISBN 978-2-8322-9390-4

– 2 – IEC 60079-26:2021 © IEC 2021
CONTENTS
FOREWORD . 4
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Ex Equipment with two combined Types of Protection . 8
4.1 General . 8
4.2 Basic requirements . 8
4.3 Electrical Connections . 9
5 Ex Equipment containing parts with different EPLs and a separation element . 9
5.1 General . 9
5.2 Separation elements . 9
5.2.1 General . 9
5.2.2 Basic requirements . 10
5.2.3 Mechanical partition walls . 10
5.2.4 Metallic partition walls with gas-tight conductor bushings . 10
5.2.5 Partition wall supplemented with a joint . 11
5.2.6 Partition wall for explosive gas atmospheres supplemented with natural
ventilation . 11
5.2.7 Requirements depending on the thickness of the partition wall . 12
6 Process connection . 13
7 Type tests . 14
7.1 Standardized Types of Protection . 14
7.2 Separation elements . 14
7.3 Temperature evaluation . 14
8 Marking . 14
8.1 General . 14
8.2 Ex Equipment with two combined Types of Protection . 14
8.3 Ex Equipment containing parts with different EPLs. 15
8.4 Examples of marking:. 15
9 Instructions . 16
9.1 Separation elements . 16
9.2 Process connection . 16
9.3 EPL allocation . 16
Annex A (normative)  Types of construction for separation elements . 17
Bibliography . 23

Figure 1 – Partition wall with a conductor bushing considered as gas diffusion tight. 11
Figure 2 – Example of a separation element with a cylindrical shaft joint and ventilation . 12
Figure 3 – Example g) of marking of equipment with a separation element. 15

Table 1 – Requirements for Ex Equipment containing parts with different EPLs. . 9
Table A.1 – Ex Equipment with separation elements mounted at a boundary of Zone 0. 17
Table A.2 – Ex Equipment with separation elements mounted at a boundary of Zone 1. 18
Table A.3 – Ex Equipment with separation elements mounted at a boundary of Zone 20 . 19
Table A.4 – Ex Equipment with separation elements mounted at a boundary of Zone 21 . 19

IEC 60079-26:2021 © IEC 2021 – 3 –
Table A.5 – Ex Equipment with separation elements mounted at a boundary of Zone 0
in Zone 21 or 22 . 20
Table A.6 – Ex Equipment with separation elements mounted at a boundary of Zone 1
in Zone 21 or 22 . 20
Table A.7 – Ex Equipment with separation elements mounted at a boundary of Zone 20
in Zone 1 or 2 . 21
Table A.8 – Ex Equipment with separation elements mounted at a boundary of Zone 21
in Zone 1 or 2 . 22

– 4 – IEC 60079-26:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLOSIVE ATMOSPHERES –
Part 26: Equipment with Separation Elements
or combined Levels of Protection

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60079-26 has been prepared by IEC technical committee 31:
Equipment for explosive atmospheres.
This fourth edition cancels and replaces the third edition published in 2014 and constitutes a
technical revision.
IEC 60079-26:2021 © IEC 2021 – 5 –
This edition includes the following significant changes with respect to the previous edition:
Type
Minor and Major
Changes Clause
editorial Extension technical
changes changes
The scope of the standard was extended for separation 5 x
elements between all EPLs for gas and dust hazardous
areas as well as for non-electrical equipment. The title
and the structure of the standard was modified
accordingly.
The requirements for combined Types of Protection 4.1.2 4 x
were restructured and included in Clause 4
The requirements for equipment with moving parts was 4.2 x
removed and transferred to IEC 60079-0 (ed. 3)
For equipment with partition walls other than corrosion 7.2  C1
resistant metals, glass or ceramic the type tests were
detailed and the cycling test acc. to IEC TS 60079-40
specified, if they were exposed to constant vibrational
stress
The marking is extended for equipment to be mounted 8 x
between different Zones
The thickness of the partition wall must be specified in 9 x
the instructions
Additional warnings are included in the instructions for 9 x
equipment with separation elements exposed to abrasive
dust flow
Table 1 "Separation elements" was moved to Annex A as Table A.1 x
Table A.1 and modified for clarification
Table A.2 to table A.8 added for the extended separation
x
elements
NOTE The technical changes referred to include the significance of technical changes in the revised IEC Standard,
but they do not form an exhaustive list of all modifications from the previous version.
Explanation of the types of changes:
A) Definitions
1. Minor and editorial changes:
• Clarification
• Decrease of technical requirements
• Minor technical change
• Editorial corrections
These are changes which modify requirements in an editorial or a minor technical way. They
include changes of the wording to clarify technical requirements without any technical change,
or a reduction in level of existing requirement.
2. Extension: Addition of technical options
These are changes which add new or modify existing technical requirements, in a way that new
options are given, but without increasing requirements for equipment that was fully compliant
with the previous standard. Therefore, these will not have to be considered for products in
conformity with the preceding edition.

– 6 – IEC 60079-26:2021 © IEC 2021
3. Major technical changes:
• addition of technical requirements
• increase of technical requirements
These are changes to technical requirements (addition, increase of the level or removal) made
in a way that a product in conformity with the preceding edition will not always be able to fulfil
the requirements given in the later edition. These changes have to be considered for products
in conformity with the preceding edition. For these changes additional information is provided
in clause B below.
NOTE These changes represent current technological knowledge. However, these changes should not normally
have an influence on equipment already placed on the market.
B) Information about the background of ‘Major technical changes’
C1 to ensure that partition walls consisting of materials other than stainless steel, ceramics or
glass, which are exposed to pressure or vibrational stress, provide a comparable level of
safety, additional endurance tests were included. Reference to tests in IEC TS 60079-40
were considered appropriate.
The text of this International Standard is based on the following documents:
FDIS Report on voting
31/1562/FDIS 31/1564/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60079 series, published under the general title Explosive
atmospheres, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

IEC 60079-26:2021 © IEC 2021 – 7 –
EXPLOSIVE ATMOSPHERES –
Part 26: Equipment with Separation Elements
or combined Levels of Protection

1 Scope
This part of IEC 60079 specifies requirements for construction, testing and marking for Ex
Equipment that contains parts of the equipment with different Equipment Protection Levels
(EPLs) and a separation element. This equipment is mounted across a boundary where different
EPLs are required, for example between different gas hazardous areas, dust hazardous areas
or gas hazardous areas adjacent to dust hazardous areas.
EXAMPLE: Equipment installed in the wall of storage tanks located in Zone 1 and containing Zone 0 inside.
Separation elements are considered for both electrical and non-electrical equipment. If
mechanical energy can be transformed into a potential ignition source, additionally an ignition
hazard assessment in accordance with ISO 80079-36 is performed and appropriate measures
are undertaken. Suitable measures can be selected from ISO 80079-37 or IEC TS 60079-42.
This document also specifies requirements for the combination of two Types of Protection, each
with EPL Gb, to achieve EPL Ga. Examples are included in 4.2.
This document supplements and modifies the general requirements of IEC 60079-0. Where a
requirement of this document conflicts with a requirement of IEC 60079-0, the requirement of
this document takes precedence.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements
IEC 60079-1, Explosive atmospheres – Part 1: Equipment protection by flameproof enclosures
"d"
IEC 60079-11, Explosive atmospheres – Part 11: Equipment protection by intrinsic safety "i"
IEC 60079-31, Explosive atmospheres – Part 31: Equipment dust ignition protection by
enclosure "t"
IEC TS 60079-40, Explosive atmospheres – Part 40: Requirements for process sealing between
flammable process fluids and electrical systems
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60695-11-10, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and vertical
flame test methods
– 8 – IEC 60079-26:2021 © IEC 2021
ISO 80079-36, Explosive atmospheres – Part 36: Non-electrical equipment for explosive
atmospheres – Basic method and requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60079-0 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Ex Equipment with two combined Types of Protection
4.1 General
To achieve EPL Ga, electrical equipment may comply with the requirements of two independent
Types of Protection each of EPL Gb. If one Type of Protection fails, the other Type of Protection
shall continue to function. Then even during rare malfunctions, for example two independent
faults, no ignition source can occur.
4.2 Basic requirements
The independent Types of Protection shall not have a common mode of failure, except as
specified below (see a) and b)). Combined Types of Protection of EPL Gb shall depend on
different physical protection principles.
NOTE 1 An example for an unacceptable common mode of failure is an Ex "db" enclosure containing arcing
components installed inside an Ex "eb" enclosure. Should the Ex "db" enclosure be compromised, it would also
compromise the Ex "eb" enclosure.
NOTE 2 The combination of Ex "db" and Ex "q" both depend on the avoidance of flame propagation (same physical
protection principle) and are not suitable in combination. In practice, some combinations are not suitable, for example
the combination of liquid immersion "ob" and powder filling "q".
Both Types of Protection shall be assessed using the most onerous malfunction condition of
the other Type of Protection. When combining intrinsic safety, i.e. Level of Protection "ib", with
another Type of Protection, the second Type of Protection shall be assessed after the
application of faults to the intrinsically safe apparatus which result in the most onerous condition
as specified in IEC 60079-11. Thermal dissipation shall be considered in case of a fault of one
Type of Protection.
When using two Types of Protection, which both rely on the same parameter (for example, the
creepage distance when combining Ex "ib" with Ex "eb"), the most stringent requirement of both
Types of Protection shall be applied.
If two Types of Protection are combined which both rely on the enclosure, one of the following
shall be met:
a) if two enclosures are used (one totally enclosed within the other), each enclosure shall
comply with the requirements of the respective Type of Protection; or
b) if only one enclosure is used, the enclosure and the Cable Glands shall meet the impact
test requirements of IEC 60079-0, using the Group I values.
Examples of relevant combinations of two independent Types of Protection are as follows:
– inductive transmitters (for example proximity switches, electrical position sensors) with
intrinsic safety "ib" enclosed by encapsulation "mb";

IEC 60079-26:2021 © IEC 2021 – 9 –
NOTE The connections to intrinsically safe "ib" circuits can be protected by increased safety "eb";
– a luminaire designed as increased safety "eb" included in a flameproof enclosure "db";
– measuring transducers with intrinsic safety "ib" enclosed by a flameproof enclosure "db";
– equipment with electrical circuits of intrinsic safety "ib", additionally protected by powder
filling "q";
– electromagnetic valves with encapsulation "mb", enclosed by a flameproof enclosure "db";
– increased safety "eb", with pressurized equipment "pxb".
4.3 Electrical Connections
Electrical connections and permanently connected cables of the equipment sited within an area
requiring EPL Ga shall comply with EPL Ga.
NOTE Installation requirements for equipment with EPL Ga achieved by combined types of protection are in
IEC 60079-14, Edition 6 .
5 Ex Equipment containing parts with different EPLs and a separation element
5.1 General
Equipment which is mounted through or forms part of the boundary wall between different Zones
may contain different parts which comply with different EPLs. In this case the equipment shall
contain a separation element between the different parts of the equipment (see Table 1).
Table 1 – Requirements for Ex Equipment containing parts with different EPLs.
Part complying with
EPL Ga EPL Gb EPL Da EPL Db
EPL Gb Tab
...