EN IEC 60721-3-3:2019/A1:2026
(Amendment)Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations
- Status
- Published
- Publication Date
- 22-Oct-2026
- Technical Committee
- CLC/SR 104 - Environmental conditions, classification and methods of test
- Current Stage
- 6060 - Document made available - Publishing
- Start Date
- 23-Oct-2026
- Due Date
- 25-Apr-2025
- Completion Date
- 23-Oct-2026
EN IEC 60721-3-3:2019/A1:2026 is a CLC amendment to the classification of environmental conditions for stationary use at weatherprotected locations. It updates the way the standard classifies chemically active substances and mechanical conditions, so users can describe the site atmosphere, vibration and shock level in a common technical language.
What does EN IEC 60721-3-3:2019/A1:2026 specify?
EN IEC 60721-3-3:2019/A1:2026 updates Part 3-3 of IEC 60721 for stationary installations at weatherprotected locations. The amendment is centered on clause 5 and adds an informative annex for atmospheric contaminants.
The document is organized around:
- updated subclause 5.5 on chemically active substances
- updated subclause 5.7 on mechanical conditions
- a revised Table 5 and Figures 1 to 3 for vibration and shock
- new informative Annex C for classification of chemically active substances
| Annex | What it covers |
|---|---|
| Annex B | Definition of the seismic environment |
| Annex C | Classification of chemically active substances |
What are the key requirements of EN IEC 60721-3-3:2019/A1:2026?
Chemically active substances (C)
Clause 5.5 says that chemical contamination of the atmosphere mainly comes from industrial emissions, motor-driven vehicles and heating systems, with sea salt and road salt aerosols also contributing. In practice, the user needs to think about the local air chemistry because it can affect both function and materials.
Clause 5.5 allows the classification to be based either on ISO 9223 or on the classification in Annex C. That matters because the choice is application-dependent - the same site can be described with a different classification method depending on what the user needs to specify.
Annex C introduces the classes 3C1R, 3C1L, 3C1, 3C2, 3C3 and 3C4, and Table C.1 gives the contaminant levels behind them. For users, this means the document supports both broad location categories and a more detailed contaminant-by-contaminant description.
Annex C also distinguishes maximum values from mean values. In practice, maximum values describe short peaks, while mean values describe long-term exposure, so both the short-term and long-term effect on materials can be considered.
Mechanical conditions (M)
Clause 5.7 treats mechanical conditions as vibration and shock at the location, for example from normal operations or nearby vehicular movement. This is the basis for matching the site environment to the right severity class before design or qualification work starts.
The updated Table 5 classifies stationary vibration, sinusoidal; stationary vibration, random; and non-stationary vibration including shock. That matters because different equipment and different vibration sources are described in different ways.
The mechanical classes run from 3M10 to 3M14, moving from insignificant to extremely high vibration and shock. In practical terms, a user selects the class that best matches the actual installation, such as a location near air conditioning, machinery, conveyor belts or heavy machinery.
Figures 1 to 3 give the graphical forms of these mechanical conditions, and Annex B is referenced for the seismic environment. That helps users separate ordinary vibration and shock from earthquake-related conditions when they specify or test the environment.
What terms does EN IEC 60721-3-3:2019/A1:2026 define?
- Chemically active substances (C) - atmospheric contaminants that can affect product function and materials.
- Mechanical conditions (M) - the vibration and shock levels present at the location.
- 3C1R - a location with a stringently monitored and controlled atmosphere, identified as a clean room category.
- 3C1L - a location with a continuously controlled atmosphere.
- 3C2 - a location in an urban area with industrial activities or heavy traffic.
- 3M12 - a location with moderate vibration and shock, such as near machinery and conveyor belts.
- Non-stationary vibration including shock - a mechanical condition that can occur together with stationary vibration and is represented by shock response spectrum curves.
Who uses EN IEC 60721-3-3:2019/A1:2026?
EN IEC 60721-3-3:2019/A1:2026 is used by engineers, quality managers, buyers and test laboratories that need to describe the environment for a stationary installation at a weatherprotected location. It is also useful in procurement, design verification and environmental qualification, where the site conditions have to be translated into a clear severity class.
What changed in EN IEC 60721-3-3:2019/A1:2026 from the previous edition?
EN IEC 60721-3-3:2019/A1:2026 amends IEC 60721-3-3:2019 by:
- replacing subclause 5.5 with updated text on chemically active substances
- replacing subclause 5.7 with updated text on mechanical conditions
- deleting the existing Table 5 and all figures, and replacing them with a new Table 5 and Figures 1 to 3
- adding informative Annex C for the classification of chemically active substances
Which standards are used with EN IEC 60721-3-3:2019/A1:2026?
- ISO 9223 - named as one of the two ways to classify chemically active substances; it provides an alternative basis for the environmental classification of atmospheric corrosion conditions.
What does the EN IEC 60721-3-3:2019/A1:2026 document contain?
EN IEC 60721-3-3:2019/A1:2026 contains revised descriptive text for chemical and mechanical environmental conditions, together with a new classification table and figures for vibration and shock. Annex C adds Table C.1 and explanatory notes on how to apply maximum values, mean values and the 3C1R to 3C4 classes. The document is used when selecting environmental severities for design, testing, qualification and site specification.
Relations
- Effective Date
- 27-Oct-2026
- Effective Date
- 27-Oct-2026
- Effective Date
- 27-Oct-2026
- Effective Date
- 27-Oct-2026
- Effective Date
- 27-Oct-2026
- Effective Date
- 11-Jun-2024
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Frequently Asked Questions
EN IEC 60721-3-3:2019/A1:2026 is a amendment published by CLC. Its full title is "Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations". This standard covers: Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations
Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations
EN IEC 60721-3-3:2019/A1:2026 is classified under the following ICS (International Classification for Standards) categories: 19.040 - Environmental testing. The ICS classification helps identify the subject area and facilitates finding related standards.
EN IEC 60721-3-3:2019/A1:2026 has the following relationships with other standards: It is inter standard links to EN 50617-1:2015, EN IEC 61987-1:2024, EN IEC 61514:2026, EN 60770-3:2014, EN IEC 61514-2:2026, EN IEC 60721-3-3:2019. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN IEC 60721-3-3:2019/A1:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2026
Klasifikacija okoljskih pogojev - 3-3. del: Klasifikacija skupin okoljskih parametrov
in njihove resnosti - Stacionarna uporaba na lokacijah, zaščitenih pred
vremenskimi vplivi - Dopolnilo A1 (IEC 60721-3-3:2019/AMD1:2026)
Amendment 1 - Classification of environmental conditions - Part 3-3: Classification of
groups of environmental parameters and their severities - Stationary use at
weatherprotected locations (IEC 60721-3-3:2019/AMD1:2026)
Klassifizierung von Umgebungsbedingungen - Teil 3-3: Klassen von Einflussgrößen und
deren Grenzwerte – Ortsfester Einsatz, wettergeschützt (IEC 60721-3-
3:2019/AMD1:2026)
Classification des conditions d'environnement - Partie 3-3: Classification des
groupements des agents d'environnement et de leurs sévérités - Utilisation à poste fixe,
protégé contre les intempéries (IEC 60721-3-3:2019/AMD1:2026)
Ta slovenski standard je istoveten z: EN IEC 60721-3-3:2019/A1:2026
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 60721-3-3:2019/A1
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2026
ICS 19.040
English Version
Classification of environmental conditions - Part 3-3:
Classification of groups of environmental parameters and their
severities - Stationary use at weatherprotected locations
(IEC 60721-3-3:2019/AMD1:2026)
Classification des conditions d'environnement - Partie 3-3: Klassifizierung von Umgebungsbedingungen - Teil 3-3:
Classification des groupements des agents Klassen von Einflussgrößen und deren Grenzwerte -
d'environnement et de leurs sévérités - Utilisation à poste Ortsfester Einsatz, wettergeschützt
fixe, protégé contre les intempéries (IEC 60721-3-3:2019/AMD1:2026)
(IEC 60721-3-3:2019/AMD1:2026)
This amendment A1 modifies the European Standard EN IEC 60721-3-3:2019; it was approved by CENELEC on 2026-10-20. CENELEC
members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this amendment 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 amendment 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
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60721-3-3:2019/A1:2026 E
European foreword
The text of document 104/1188/FDIS, future edition 3 of IEC 60721-3-3/AMD1, prepared by TC 104
"Environmental conditions, classification and methods of test" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN IEC 60721-3-3:2019/A1:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-10-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-10-31
document have to be withdrawn
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.
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 60721-3-3:2019/AMD1:2026 was approved by CENELEC
as a European Standard without any modification.
IEC 60721-3-3 ®
Edition 3.0 2026-09
INTERNATIONAL
STANDARD
AMENDMENT 1
Classification of environmental conditions -
Part 3-3: Classification of groups of environmental parameters and their
severities - Stationary use at weatherprotected locations
ICS 19.040 ISBN 978-2-8327-1480-5
IEC 60721-3-3:2019-05/AMD1:2026-09(en)
IEC 60721-3-3:2019/AMD1:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Classification of environmental conditions -
Part 3-3: Classification of groups of environmental parameters and their
severities - Stationary use at weatherprotected locations
AMENDMENT 1
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
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
Amendment 1 to IEC 60721-3-3:2019 has been prepared by IEC technical committee 104:
Environmental conditions, classification and methods of test.
The text of this Amendment is based on the following documents:
Draft Report on voting
104/1188/FDIS 104/1204/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used
...