EN IEC 60721-3-4:2019

Classification of environmental conditions - Part 3-4: Classification of groups of environmental parameters and their severities - Stationary use at non-weatherprotected locations

IEC 60721-3-4:2019 classifies groups of environmental parameters and their severities to which products are subjected when installed for stationary use at non-weatherprotected locations. Weatherprotected locations where products can be mounted for stationary use permanently or temporarily are addressed in IEC 60721-3-3. This third edition cancels and replaces the second edition published in 1995 and Amendment 1:1996. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Clause 1: reworded. b) Clause 2: normative references have been updated. c) Clause 3: definitions have been updated. d) Clause 4: reworded and simplified. e) Clause 5: revised and updated. Several classes have been replaced by completely new classes based on the use of new information obtained from referenced technical reports. f) Defined values of chemically active substances are now by reference to ISO 9223. g) Tables 1 through 5: updated.

Klassifizierung von Umweltbedingungen - Teil 3-4: Klassen von Umwelteinflußgrößen und deren Grenzwerte - Ortsfester Einsatz, nicht wettergeschützt

Classification des conditions d'environnement - Partie 3-4: Classification des groupements des agents d'environnement et de leurs sévérités - Utilisation à poste fixe, non protégé contre les intempéries

L’IEC 60721-3-4:2019 classifie les groupements d’agents d’environnement et leurs sévérités, auxquels sont soumis des produits montés pour une utilisation à poste fixe dans des emplacements non protégés contre les intempéries. Les emplacements protégés contre les intempéries où peuvent être montés les produits pour une utilisation fixe de manière permanente ou temporaire sont traités dans l’IEC 60721-3-3. Cette troisième édition annule et remplace la deuxième édition parue en 1995, ainsi que son amendement 1:1996. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) Article 1: reformulation. b) Article 2: mise à jour des références normatives. c) Article 3: mise à jour des définitions. d) Article 4: reformulation et simplification. e) Article 5: révision et mise à jour. Plusieurs catégories ont été remplacées par des catégories totalement nouvelles fondées sur l’utilisation de nouvelles informations obtenues dans les rapports techniques cités en référence; f) Les valeurs définies des substances chimiquement actives font désormais référence à l’ISO 9223. g) Tableaux 1 à 5: mise à jour.

Klasifikacija okoljskih pogojev - 3-4. del: Klasifikacija skupin okoljskih parametrov in njihove resnosti - Stacionarna uporaba na lokacijah, ki niso zaščitene pred vremenskimi vplivi (IEC 60721-3-4:2019)

Ta del standarda IEC 60721 razvršča skupine okoljskih parametrov in njihove resnosti, katerim so izdelki lahko izpostavljeni pri namestitvi za stacionarno uporabo na lokacijah, ki niso zaščitene pred vremenskimi vplivi. Lokacije, ki so zaščitene pred vremenskimi vplivi, kjer so izdelki nameščeni za trajno ali začasno stacionarno uporabo obravnava standard IEC 60721-3-3.
Okoljski pogoji, navedeni v tem dokumentu, so omejeni na tiste, ki lahko neposredno vplivajo na delovanje izdelkov. Obravnavani so samo okoljski pogoji, ki ustrezajo zgornjemu opisu. Na izdelkih ni podan noben poseben opis vplivov teh pogojev.
Okoljski pogoji, ki so neposredno povezani z nevarnostjo požara ali eksplozije, mikroklimo v izdelku, in pogoji, ki so povezani z učinki ionizirajočega sevanja, so izključeni. Vsakršni drugi nepredvideni dogodki so prav tako izključeni.
Navedeno je omejeno število razredov okoljskih pogojev, ki zajemajo široko področje uporabe.

General Information

• Status: Published
• Publication Date: 18-Jul-2019
• Withdrawal Date: 25-Jun-2022
• ICS: 19.040 - Environmental testing
• Technical Committee: CLC/SR 104 - Environmental conditions, classification and methods of test
• Drafting Committee: IEC/TC 104 - IEC_TC_104
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 19-Jul-2019
• Completion Date: 19-Jul-2019
• Ref Project: SIST EN IEC 60721-3-4:2019 - Classification of environmental conditions - Part 3-4: Classification of groups of environmental parameters and their severities - Stationary use at non-weatherprotected locations (IEC 60721-3-4:2019)

Relations

• Replaces: EN 60721-3-4:1995 - Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities - Section 4: Stationary use at non-weatherprotected locations
• Effective Date: 23-Jan-2023
• Replaces: EN 60721-3-4:1995/A1:1997 - Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities - Section 4: Stationary use at non-weatherprotected locations
• Effective Date: 23-Jul-2019
• Corrected By: EN IEC 60721-3-4:2019/AC:2023-08 - Classification of environmental conditions - Part 3-4: Classification of groups of environmental parameters and their severities - Stationary use at non-weatherprotected locations
• Effective Date: 08-Aug-2023

Overview

EN IEC 60721-3-4:2019 (IEC 60721-3-4) specifies how to classify groups of environmental parameters and their severities for products installed for stationary use at non‑weatherprotected locations. This third edition (2019) replaces the earlier editions (1995 + A1:1996) and constitutes a technical revision that updates normative references, definitions and many classification classes. It is intended to help manufacturers, designers and test engineers define short‑term environmental stresses that can directly affect product performance outdoors where there is no weather protection.

Key topics

• Scope and exclusions: covers environmental parameters that directly affect product performance for stationary, non‑weatherprotected installations. Excludes fire/explosion hazards, product internal microclimates, ionizing radiation and unforeseen incidents.
• Classification groups (Clause 5): provides classes and severities for:
  • Climatic conditions (K)
  • Special climatic conditions (Z)
  • Biological conditions (B)
  • Chemically active substances (C) - values referenced to ISO 9223 for corrosion/air‑pollution parameters
  • Mechanically active substances (S)
  • Mechanical conditions (M)
• Updated content: Clause 1 reworded; Clause 2 normative references updated; Clause 3 definitions updated; Clause 4 simplified; Clause 5 revised with several classes replaced or newly defined; Tables 1–5 updated to reflect revised classifications.
• Informative guidance: includes notes on interdependence of temperature and humidity and a seismic environment definition (informative annexes).

Practical applications

• Product specification: use EN IEC 60721-3-4:2019 to specify environmental classes (e.g., K, C, M, B, S, Z) in procurement documents and datasheets for outdoor electrical/electronic equipment.
• Design and materials selection: select enclosures, coatings and components based on classified severities (corrosion categories via ISO 9223, mechanical loads, biological exposure).
• Test planning and validation: derive short‑term environmental stress limits to plan laboratory tests, accelerated ageing and field verifications.
• Risk reduction and compliance: harmonize environmental requirements across suppliers and support conformity assessment and warranty claims.

Who should use this standard

• Electrical/electronic product designers and engineers
• Test laboratories and certification bodies
• Procurement/specification authors and project engineers (telecoms, power systems, industrial automation, infrastructure)
• Corrosion and reliability engineers

Related standards

• IEC 60721 series (other parts for different mounting/use conditions)
• ISO 9223 (air pollution - corrosivity of atmospheres) - referenced for chemically active substances
• IEC 60068 series and IEC/TR documents referenced for further environmental testing guidance

EN IEC 60721-3-4:2019 is a practical classification tool for anyone specifying or testing equipment exposed to outdoor, non‑weatherprotected environments. Use it to create clear, testable environmental requirements and to align material and test choices with recognized severity classes.

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2019
Nadomešča:
SIST EN 60721-3-4:2001
SIST EN 60721-3-4:2001/A1:2002
Klasifikacija okoljskih pogojev - 3-4. del: Klasifikacija skupin okoljskih parametrov
in njihove resnosti - Stacionarna uporaba na lokacijah, ki niso zaščitene pred
vremenskimi vplivi (IEC 60721-3-4:2019)
Classification of environmental conditions - Part 3-4: Classification of groups of
environmental parameters and their severities - Stationary use at non-weatherprotected
locations (IEC 60721-3-4:2019)
Klassifizierung von Umweltbedingungen - Teil 3-4: Klassen von Umwelteinflußgrößen
und deren Grenzwerte - Ortsfester Einsatz, nicht wettergeschützt (IEC 60721-3-4:2019)
Classification des conditions d'environnement - Partie 3-4: Classification des
groupements des agents d'environnement et de leurs sévérités - Utilisation à poste fixe,
non protégé contre les intempéries (IEC 60721-3-4:2019)
Ta slovenski standard je istoveten z: EN IEC 60721-3-4:2019
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 60721-3-4

NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2019
ICS 19.040 Supersedes EN 60721-3-4:1995 and all of its
amendments and corrigenda (if any)
English Version
Classification of environmental conditions - Part 3-4:
Classification of groups of environmental parameters and their
severities - Stationary use at non-weatherprotected locations
(IEC 60721-3-4:2019)
Classification des conditions d'environnement - Partie 3-4: Klassifizierung von Umgebungsbedingungen - Teil 3-4:
Classification des groupements des agents Klassen von Einflussgrößen und deren Grenzwerte –
d'environnement et de leurs sévérités - Utilisation à poste Ortsfester Einsatz, nicht wettergeschützt
fixe, non protégé contre les intempéries (IEC 60721-3-4:2019)
(IEC 60721-3-4:2019)
This European Standard was approved by CENELEC on 2019-06-26. 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,
Turkey 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
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60721-3-4:2019 E

European foreword
The text of document 104/828/FDIS, future edition 3 of IEC 60721-3-4, prepared by IEC/TC 104 "Environmental
conditions, classification and methods of test" was submitted to the IEC-CENELEC parallel vote and approved
by CENELEC as EN IEC 60721-3-4:2019.
The following dates are fixed:
• latest date by which the document has to be implemented at national level by (dop) 2020-03-26
publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-06-26
document have to be withdrawn
This document supersedes EN 60721-3-4:1995 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.

Endorsement notice
The text of the International Standard IEC 60721-3-4:2019 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 standards indicated:
IEC 60068-2-27 NOTE Harmonized as EN 60068-2-27
IEC 60068-3-3 NOTE Harmonized as EN 60068-3-3
IEC 60721-2 (series) NOTE Harmonized as EN 60721-2 (series)
IEC 60721-1 NOTE Harmonized as EN 60721-1
IEC 60721-2-1 NOTE Harmonized as EN 60721-2-1
IEC 60721-2-2 NOTE Harmonized as EN 60721-2-2
IEC 60721-2-3 NOTE Harmonized as EN 60721-2-3
IEC 60721-2-4 NOTE Harmonized as EN IEC 60721-2-4
IEC 60721-2-5 NOTE Harmonized as HD 478.2.5 S1
IEC 60721-2-6:1990 NOTE Harmonized as HD 478.2.6 S1:1993 (not modified)
IEC 60721-2-9 NOTE Harmonized as EN 60721-2-9
IEC 60721-3 (series) NOTE Harmonized as EN 60721-3-9 (series)
IEC 60721-3-0 NOTE Harmonized as EN 60721-3-0
IEC 60721-3-3 NOTE Harmonized as EN 60721-3-3
ISO 9223 NOTE Harmonized as EN ISO 9223

IEC 60721-3-4 ®
Edition 3.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Classification of environmental conditions –

Part 3-4: Classification of groups of environmental parameters and their

severities – Stationary use at non-weatherprotected locations

Classification des conditions d'environnement –

Partie 3-4: Classification des groupements des agents d'environnement et de

leurs sévérités – Utilisation à poste fixe, non protégé contre les intempéries

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-6956-5

– 2 – IEC 60721-3-4:2019 © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 General . 6
5 Classification of groups of environmental parameters and their severities . 7
5.1 General . 7
5.2 Climatic conditions (K) . 7
5.3 Special climatic conditions (Z). 8
5.4 Biological conditions (B) . 8
5.5 Chemically active substances (C) . 8
5.6 Mechanically active substances (S) . 8
5.7 Mechanical conditions (M) . 8
(informative) Interdependence of air temperature, relative air humidity, and
absolute air humidity . 12
(informative) Definition of seismic environment . 13
Bibliography . 15

Figure A.1 – Climatogram of interdependence of air temperature, relative air humidity,
and absolute air humidity . 12

Table 1 – Classification of climatic conditions . 9
Table 2 – Classification of special climatic conditions . 10
Table 3 – Classification of biological conditions . 10
Table 4 – Classification of mechanically active substances . 10
Table 5 – Classification of mechanical conditions . 11
Table B.1 – Correlation of seismic zones with expected magnitudes . 14

IEC 60721-3-4:2019 © IEC 2019 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 3-4: Classification of groups of environmental parameters and
their severities – Stationary use at non-weatherprotected locations

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 60721-3-4 has been prepared by IEC technical committee 104:
Environmental conditions, classification, and methods of test.
This third edition cancels and replaces the second edition published in 1995 and
Amendment 1:1996. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Clause 1: reworded.
b) Clause 2: normative references have been updated.
c) Clause 3: definitions have been updated.
d) Clause 4: reworded and simplified.

– 4 – IEC 60721-3-4:2019 © IEC 2019
e) Clause 5: revised and updated. Several classes have been replaced by completely new
classes based on the use of new information obtained from referenced technical reports.
f) Defined values of chemically active substances are now by reference to ISO 9223.
g) Tables 1 through 5: updated.
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/828/FDIS 104/836/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 60721 series, published under the general title Classification of
environmental conditions, 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.
IEC 60721-3-4:2019 © IEC 2019 – 5 –
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 3-4: Classification of groups of environmental parameters and
their severities – Stationary use at non-weatherprotected locations

1 Scope
This part of IEC 60721 classifies groups of environmental parameters and their severities to
which products are subjected when installed for stationary use at non-weatherprotected
locations. Weatherprotected locations where products can be mounted for stationary use
permanently or temporarily are addressed in IEC 60721-3-3.
The environmental conditions specified in this document are limited to those which can
directly affect the performance of products. Only environmental conditions as such are
considered. No special description of the effects of these conditions on the products is
provided.
Environmental conditions directly related to fire or explosion hazards, microclimate within a
product, and conditions related to effects from ionizing radiation are excluded. Any other
unforeseen incidents are also excluded.
A limited number of classes of environmental conditions is given, covering a broad field of
application.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
3.1
stationary use
use of a product mounted firmly on a structure, or permanently placed at a certain site
3.2
non-weatherprotected location
location at which a product is not protected from meteorological conditions
3.3
sheltered location
location at which a product is covered by a structure to protect it from direct meteorological
conditions, i.e. direct sunlight, heavy rain

– 6 – IEC 60721-3-4:2019 © IEC 2019
4 General
A product may be subjected to a range of environmental conditions during its lifetime. These
conditions have been separated into classes described in IEC 60721-3 (all parts). The classes
given may be used for defining the maximum short-term environmental stresses on a product.
However, they do not provide information regarding the long-term or total lifetime
environmental stresses a product may experience. This means that no reliability or lifetime
assessment is possible based on these classes alone. Refer to IEC 60721-2 (all parts) and
applicable technical reports (IEC TR 62130, IEC TR 62131-2, IEC TR 62131-3,
IEC TR 62131-4 and IEC TR 62131-5) for further information on actual environmental
conditions.
A product may be simultaneously exposed to several environmental parameters, for example,
solar radiation and temperature, temperature and humidity, as well as vibration and
temperature change. Combinations of the environmental parameters given may increase the
stress effect on a product. Therefore, combined conditions should be considered in the design
and evaluation of a product.
Products should be designed to survive and operate in different environments. Basically, they
will be affected by environmental influences in two ways:
– by the effects of short-term extreme environmental conditions which may directly cause
malfunction or destroy the product;
– by the effect of long-term subjection to non-extreme environmental stresses which may
slowly degrade the product and finally cause malfunction or destruction of the product.
Short-term extreme environmental conditions may occur at any time in a product's life. A
product may be unaffected by an extreme condition when it is new but fail when it is subjected
to the same condition after being used for a long period of time due to the effect of ageing.
The order in which the environmental conditions are applied may affect the results of an
evaluation.
It is important for
...