SIST EN IEC 60721-3-5:2026

Classification of environmental conditions - Part 3-5: Classification of groups of environmental parameters and their severities - Ground vehicle installations (IEC 60721-3-5:2026)

IEC 60721-3-5:2026 classifies the groups of environmental parameters and their severities to which a product, not forming part of the vehicle, is subjected when installed on or in a ground vehicle. Such products are for example radios, communication systems, fare meters, flow meters for liquids transported by the vehicle, for example milk, petroleum products, etc. Vehicles where products can be permanently or temporarily installed include
- road vehicles: passenger cars, commercial vehicles, special vehicles, towing vehicles, trailers, mopeds, motorcycles,
- rail vehicles: trains, trams,
- tracked vehicles: excavators, cranes, rubber tracked vehicles,
- overland vehicles: four-wheel drive cars, tractors, snow scooters,
- handling and storage vehicles: fork-lift trucks (manual and robot), luggage transporters, and
- self-propelled machinery: diggers, harvesters.
This third edition cancels and replaces the second edition, published in 1997. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) most classes have been replaced by completely new classes based on the use of additional information obtained from referenced Technical Reports;
b) Table 1 through to Table 7 have been reviewed and updated;
c) the content of Annex A and Annex B has either been incorporated into the main body of the document or deleted.

Klassifizierung von Umgebungsbedingungen - Teil 3-5: Klassen von Einflussgrößen und deren Grenzwerte - Einsatz an und in Landfahrzeugen (IEC 60721-3-5:2026)

Classification des conditions d'environnement - Partie 3: Classification des groupements des agents d'environnement et de leurs sévérités - Section 5: Installations des véhicules terrestres (IEC 60721-3-5:2026)

L'IEC 60721-3-5:2026 classifie les groupements des agents d'environnement et leurs sévérités, auxquels est soumis un produit qui ne fait pas partie du véhicule, lorsque le produit est installé sur ou dans un véhicule terrestre. Les exemples de tels produits sont les récepteurs radio, les systèmes de communication, les compteurs de kilométrage/tarification, les débitmètres pour les liquides transportés par le véhicule, par exemple lait, produits pétroliers, etc. Les véhicules à bord desquels les produits peuvent être installés de façon permanente ou provisoire comprennent
- les véhicules routiers: véhicules de tourisme, véhicules utilitaires, véhicules spéciaux, véhicules tracteurs, remorques, cyclomoteurs, motocyclettes;
- les véhicules ferroviaires: trains, tramways;
- les véhicules à chenilles: pelles, grues, véhicules à chenilles en caoutchouc;
- les véhicules tout-terrain: véhicules à quatre roues motrices, tracteurs, motoneiges;
- les véhicules de manutention et de stockage: chariots élévateurs à fourche (manuels et robotisés), convoyeurs à bagages; et
- les machines automotrices: excavatrices, moissonneuses.
Cette troisième édition annule et remplace la deuxième édition parue en 1997. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) la plupart des classes ont été remplacées par des classes totalement nouvelles, établies en fonction de l'utilisation d'informations supplémentaires obtenues dans les Rapports techniques référencés;
b) les Tableau 1 à Tableau 7 ont été revus et mis à jour;
c) le contenu de l'Annexe A et de l'Annexe B a été soit incorporé dans le corps principal du document soit supprimé.

Klasifikacija okoljskih pogojev - 3-5. del: Klasifikacija skupin okoljskih parametrov in njihove resnosti - Inštalacije v kopenskih vozilih (IEC 60721-3-5:2026)

IEC 60721-3-5:2026 razvršča skupine okoljskih parametrov in njihove resnosti, katerim je izdelek, ki ni del vozila, izpostavljen, ko je nameščen na ali v kopenskem vozilu. Takšni izdelki so na primer radijski sprejemniki, komunikacijski sistemi, taksimetri, merilniki pretoka za tekočine, ki jih prevaža vozilo, na primer mleko, naftni proizvodi itd. Vozila, na katerih so lahko izdelki trajno ali začasno nameščeni, vključujejo
- cestna vozila: osebni avtomobili, gospodarska vozila, posebna vozila, vlečna vozila, prikolice, mopedi, motorna kolesa,
- železniška vozila: vlaki, tramvaji,
- gosenična vozila: bagri, žerjavi, vozila z gumijastimi gosenicami,
- terenska vozila: avtomobili s štirikolesnim pogonom, traktorji, snežni skuterji,
- vozila za ravnanje in skladiščenje: viličarji (ročni in robotski), transporterji za prtljago, in
- samohodna mehanizacija: bagri, kombajni.
Ta tretja izdaja razveljavlja in nadomešča drugo izdajo, objavljeno leta 1997. Ta izdaja predstavlja tehnično revizijo.
Ta izdaja vključuje naslednje pomembne tehnične spremembe v primerjavi s prejšnjo izdajo:
a) večina razredov je bila nadomeščena s popolnoma novimi razredi, ki temeljijo na uporabi dodatnih informacij, pridobljenih iz referenčnih Tehničnih poročil;
b) Tabele od 1 do 7 so bile pregledane in posodobljene;
c) vsebina Priloge A in Priloge B je bila bodisi vključena v glavno besedilo dokumenta bodisi izbrisana.

General Information

• Status: Published
• Public Enquiry End Date: 20-Mar-2025
• Publication Date: 01-Apr-2026
• ICS: 19.040 - Environmental testing
• Technical Committee: I09 - Imaginarni 09
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 04-Mar-2026
• Due Date: 09-May-2026
• Completion Date: 02-Apr-2026
• Ref Project: EN IEC 60721-3-5:2026 - Classification of environmental conditions - Part 3-5: Classification of groups of environmental parameters and their severities - Ground vehicle installations

Relations

• Replaces: SIST EN 60721-3-5:2001 - Classification of environmental conditions -- Part 3: Classification of groups of environmental parameters and their severities -- Section 5: Ground vehicle installations
• Effective Date: 01-May-2026
• Refers: SIST EN 60721-1:2001 - Classification of environmental conditions -- Part 1: Environmental parameters and their severities
• Effective Date: 10-Feb-2026
• Referred By: SIST EN 60770-3:2014 - Transmitters for use in industrial-process control systems - Part 3: Methods for performance evaluation of intelligent transmitters (IEC 60770-3:2014)
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 15827:2011 - Railway applications - Requirements for bogies and running gear
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 61881-3:2012 - Railway applications - Rolling stock equipment - Capacitors for power electronics - Part 3: Electric double-layer capacitors (IEC 61881-3:2012)
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 50125-1:2014 - Railway applications - Environmental conditions for equipment - Part 1: Equipment on board rolling stock
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 61709:2011 - Electric components - Reliability - Reference conditions for failure rates and stress models for conversion
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 61287-1:2014 - Railway applications - Power convertors installed on board rolling stock - Part 1: Characteristics and test methods
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 60077-1:2018 - Railway applications - Electric equipment for rolling stock - Part 1: General service conditions and general rules
• Effective Date: 03-Mar-2026
• Referred By: SIST EN IEC 61987-1:2025 - Industrial-process measurement and control - Data structures and elements in process equipment catalogues - Part 1: Generic structures for measuring equipment (IEC 61987-1:2024)
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 15220:2025 - Railway applications - Brake indicators
• Effective Date: 03-Mar-2026
• Referred By: SIST EN 50617-1:2015 - Railways applications - Basic parameters of train detection systems - Part 1: Track circuits
• Effective Date: 03-Mar-2026
• Referred By: SIST EN IEC 61496-1:2020 - Safety of machinery - Electro-sensitive protective equipment - Part 1: General requirements and tests (IEC 61496-1:2020)
• Effective Date: 03-Mar-2026

Overview

The kSIST FprEN IEC 60721-3-5:2025 standard, titled Classification of environmental conditions - Part 3-5: Classification of groups of environmental parameters and their severities - Ground vehicle installations, issued by the CLC, provides a comprehensive framework to classify the environmental conditions and severity levels to which products installed in or on ground vehicles are exposed. These products include items that are not integral parts of the vehicle but mounted either permanently or temporarily, such as communication systems, meters for liquids, or instrumentation devices.

This third edition is a technical revision of the 1997 edition, reflecting updated classifications based on new technical data. It is especially relevant for manufacturers, engineers, and testing laboratories involved in designing and validating equipment for various types of ground vehicles, including road vehicles, rail vehicles, tracked vehicles, and self-propelled machinery.

Key Topics

• Scope and Application
  The standard addresses the classification of environmental parameters and severity levels affecting non-vehicle integral products installed on ground vehicles like passenger cars, commercial vehicles, trains, cranes, excavators, and agricultural machinery. It excludes products forming part of the vehicle structure but can be applied to exchangeable parts with similar installation.

• Environmental Parameter Groups
  The classification organizes environmental parameters into groups with specific classes:

  • Climatic conditions (K): Covers ambient temperature, humidity, solar radiation, precipitation, and other meteorological factors affecting products.
  • Special climatic conditions (Z): Includes rare or severe weather phenomena relevant to ground vehicle installations.
  • Biological conditions (B): Addresses biological agents like fungi, insects, or rodents that may affect equipment.
  • Chemically active substances (C): Classifies corrosive chemicals or pollutants encountered.
  • Mechanically active substances (S): Covers particulate matter such as dust or abrasive particles.
  • Contaminating fluids (F) and Mechanical conditions (M): Address fluids leaking or spilled onto devices and mechanical stresses such as vibration and shock from vehicle operation.

• Severity Levels
  Each environmental parameter is further classified by severity levels identifying typical exposures ranging from mild to extreme. This helps in selecting appropriate design parameters and test conditions.

• Design and Testing Guidance
  The standard emphasizes considering combined environmental factors simultaneously-for example, vibration plus temperature variation-and the effects of both short-term extreme events and long-term exposure on product reliability. This supports realistic testing and verification protocols for ground vehicle equipment.

Applications

• Product Development for Ground Vehicles
  Helps manufacturers specify environmental requirements that products must meet when installed inside or outside vehicles, improving durability and performance under real operating conditions.

• Environmental Testing and Validation
  Laboratories and certifiers can use this classification to develop appropriate test plans simulating real-world environmental stresses like temperature cycles, mechanical shocks, humidity, and contamination.

• Specification and Procurement
  Provides standardized vocabulary and severity classifications to include in technical specifications, procurement contracts, and compliance documents for equipment used in automotive, rail, agricultural, and industrial vehicle sectors.

• Safety Critical Equipment Design
  Supports risk management by defining environmental classes that products vital to vehicle safety must withstand, ensuring operational integrity under adverse conditions.

Related Standards

• IEC 60721-1: Classification of environmental conditions - Part 1: Environmental parameters and their severities
  Foundation for terminology and parameter definitions used in Part 3-5.

• IEC 60721 Series
  Other parts address storage, transportation, and other environmental classifications complementary to ground vehicle installations.

• IEC Technical Reports (IEC TR 62130, IEC TR 62131 series)
  Provide detailed guidance on environmental measurement data and condition definitions relevant for applying this standard.

• ISO/IEC Directives, Part 2
  Relevant for the document’s drafting and publication procedures.

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Keywords: IEC 60721-3-5, ground vehicle installations, environmental classification, climatic conditions, vibration, shock, contamination, chemical exposure, biological agents, environmental severity, product testing, electrotechnical standards, vehicle-mounted equipment.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2026
Nadomešča:
SIST EN 60721-3-5:2001
Klasifikacija okoljskih pogojev - 3-5. del: Klasifikacija skupin okoljskih parametrov
in njihove resnosti - Inštalacije v kopenskih vozilih (IEC 60721-3-5:2026)
Classification of environmental conditions - Part 3-5: Classification of groups of
environmental parameters and their severities - Ground vehicle installations (IEC 60721-
3-5:2026)
Klassifizierung von Umgebungsbedingungen - Teil 3-5: Klassen von Einflussgrößen und
deren Grenzwerte - Einsatz an und in Landfahrzeugen (IEC 60721-3-5:2026)
Classification des conditions d'environnement - Partie 3: Classification des groupements
des agents d'environnement et de leurs sévérités - Section 5: Installations des véhicules
terrestres (IEC 60721-3-5:2026)
Ta slovenski standard je istoveten z: EN IEC 60721-3-5:2026
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 60721-3-5

NORME EUROPÉENNE
EUROPÄISCHE NORM February 2026
ICS 19.040 Supersedes EN 60721-3-5:1997
English Version
Classification of environmental conditions - Part 3-5:
Classification of groups of environmental parameters and their
severities - Ground vehicle installations
(IEC 60721-3-5:2026)
Classification des conditions d'environnement - Partie 3-5: Klassifizierung von Umgebungsbedingungen - Teil 3-5:
Classification des groupements des agents Klassen von Einflussgrößen und deren Grenzwerte -
d'environnement et de leurs sévérités - Installations de Einsatz an und in Landfahrzeugen
véhicules terrestres (IEC 60721-3-5:2026)
(IEC 60721-3-5:2026)
This European Standard was approved by CENELEC on 2026-02-18. 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
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60721-3-5:2026 E

European foreword
The text of document 104/1138/FDIS, future edition 3 of IEC 60721-3-5, 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 60721-3-5:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-02-28
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-02-28
document have to be withdrawn
This document supersedes EN 60721-3-5:1997 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.
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 60721-3-5:2026 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 60068-2-74 NOTE Approved as EN 60068-2-74
IEC 60721-2-1 NOTE Approved as EN 60721-2-1
IEC 60721-2-2 NOTE Approved as EN IEC 60721-2-2
IEC 60721-2-3 NOTE Approved as EN 60721-2-3
IEC 60721-2-4 NOTE Approved as EN IEC 60721-2-4
IEC 60721-2-5 NOTE Approved as HD 478.2.5 S1
IEC 60721-3 (series) NOTE Approved as EN IEC 60721-3 (series)
IEC 60721-3-0 NOTE Approved as EN IEC 60721-3-0
IEC 60721-3-1 NOTE Approved as EN IEC 60721-3-1
IEC 60721-3-2 NOTE Approved as EN IEC 60721-3-2
IEC 60721-3-5:1997 NOTE Approved as EN 60721-3-5:1997 (not modified)
ISO 9223 NOTE Approved as EN ISO 9223
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 60721-1 - Classification of environmental conditions - EN 60721-1 -
Part 1: Environmental parameters and their
severities
IEC 60721-3-5 ®
Edition 3.0 2026-01
INTERNATIONAL
STANDARD
Classification of environmental conditions -
Part 3-5: Classification of groups of environmental parameters and their
severities - Ground vehicle installations
ICS 19.040  ISBN 978-2-8327-0983-2

IEC 60721-3-5:2026-01(en)
IEC 60721-3-5:2026 © IEC 2026
CONTENTS
FOREWORD . 2
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 General . 5
5 Classification of groups of environmental parameters and their severities . 6
5.1 General . 6
5.2 Climatic conditions (K) . 6
5.3 Special climatic conditions (Z) . 9
5.4 Biological conditions (B) . 10
5.5 Chemically active substances (C) . 10
5.6 Mechanically active substances (S) . 11
5.7 Contaminating fluids (F) . 12
5.8 Mechanical conditions (M) . 12
Bibliography . 16

Figure 1 – Stationary vibration, sinusoidal . 14
Figure 2 – Stationary vibration, random . 14
Figure 3 – Non-stationary shock conditions . 15

Table 1 – Classification of climatic conditions . 8
Table 2 – Classification of special climatic conditions . 10
Table 3 – Classification of biological conditions . 10
Table 4 – Classification of chemically active substances. 11
Table 5 – Classification of mechanically active substances . 11
Table 6 – Classification of contaminating fluids. 12
Table 7 – Classification of mechanical conditions . 13

IEC 60721-3-5:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Classification of environmental conditions -
Part 3-5: Classification of groups of environmental parameters
and their severities - Ground vehicle installations

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,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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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.
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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) 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
may be required to implement this document. However, implementers are cautioned that this may not represent
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.
IEC 60721-3-5 has been prepared by IEC technical committee 104: Environmental conditions,
classification and methods of test. It is an International Standard.
This third edition cancels and replaces the second edition, published in 1997. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) most classes have been replaced by completely new classes based on the use of additional
information obtained from referenced Technical Reports;
b) Table 1 through to Table 7 have been reviewed and updated;
c) the content of Annex A and Annex B has either been incorporated into the main body of the
document or deleted.
IEC 60721-3-5:2026 © IEC 2026
The text of this International Standard is based on the following documents:
Draft Report on voting
104/1138/FDIS 104/1146/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 for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 60721-3-5:2026 © IEC 2026
1 Scope
This part of IEC 60721 classifies the groups of environmental parameters and their severities
to which a product, not forming part of the vehicle, is subjected when installed on or in a ground
vehicle. Such products are for example radios, communication systems, fare meters, flow
meters for liquids transported by the vehicle, for example milk, petroleum products, etc.
Vehicles where products can be permanently or temporarily installed include
– road vehicles: passenger cars, commercial vehicles, special vehicles, towing vehicles,
trailers, mopeds, motorcycles,
– rail vehicles: trains, trams,
– tracked vehicles: excavators, cranes, rubber tracked vehicles,
– overland vehicles: four-wheel drive cars, tractors, snow scooters,
– handling and storage vehicles: fork-lift trucks (manual and robot), luggage transporters, and
– self-propelled machinery: diggers, harvesters.
Although this document is not intended for products forming part of the vehicles, the
environmental condition classification can also be used for some exchangeable parts, installed
in a similar way and in the same locations of the vehicle as products which do not form part of
the vehicle. Only severe conditions which can be harmful to products are included.
Conditions of storage, transportation and handling are given in IEC 60721-3-1 and
IEC 60721-3-2. Classification of storage and transportation environmental conditions are given
in other subparts of the IEC 60721-3 series.
Accidental incidents are not included, but it can be important to take their occurrence into
account for products vital to the safety of the ground vehicle.
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 60721-1, Classification of environmental conditions - Part 1: Environmental parameters and
their severities
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60721-1 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1
internally mounted
mounted internally in the vehicle, in a compartment which affords some protection from the
environment, ranging from complete isolation from external influences to protection only from
precipitation when the vehicle is not moving
IEC 60721-3-5:2026 © IEC 2026
3.2
externally mounted
mounted on the outside of the vehicle and not protected from any external influences
3.3
weatherprotected
protected from the influences of meteorological conditions
3.4
non-weatherprotected
not protected from the influences of meteorological conditions
4 General
A product can be subjected to a range of environmental conditions during its lifetime. These
conditions have been separated into classes described in IEC 60721-3-0. The classes given
can 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 can experience. This means that no reliability or lifetime assessment is
possible based on these classes alone. Refer to IEC 60721-2-1, IEC 60721-2-2, IEC 60721-2-3,
IEC 60721-2-4 and IEC 60721-2-5 and applicable technical reports (IEC TR 62130 as well as
IEC TR 62131-3, IEC TR 62131-4, IEC TR 62131-5 and IEC TR 62131-8) for further
information on actual environmental conditions.
A product can be simultaneously exposed to a number of environmental parameters. For
example, solar radiation with temperature, temperature with humidity, as well as vibration with
temperature change. Combinations of the environmental parameters given can 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 can directly cause
malfunction or destroy the product;
– by the effect of long-term subjection to non-extreme environmental stresses which can
slowly degrade the product and finally cause malfunction or destruction of the product.
Short-term extreme environmental conditions can occur at any time in a product's life. A product
can 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 can affect the results of an evaluation.
It is important for the product specification, when referring to a certain class in the
IEC 60721-3 series, to define whether the product is required to be capable of operating or only
to survive without permanent damage when being exposed to the conditions described by the
class.
The environmental classes can be used as a basis for the selection of design and test severities
with respect to the consequence of failure. Information contained in the IEC 60721-3 series can
be used as a means to help establish expected requirements for use, storage, transportation,
etc., and in the development of relevant specifications. The selected severities used for testing
should attempt to produce the effects of the actual environment.
EXAMPLE 1 A high temperature test on a heat dissipating product is designed to simulate the thermal effect of
subjecting a product to conditions of high air temperature, solar radiation and other possible heat sources dependent
on the application.
IEC 60721-3-5:2026 © IEC 2026
EXAMPLE 2 In a mechanical shock test, the product can be subjected to mechanical shocks of simple pulse shapes
(e.g., half-sine), while the actual conditions cannot be described by such simple pulses.
It is recognized that extreme or special environmental conditions can exist which require
consideration of severities that are not addressed by this document.
5 Classification of groups of environmental parameters and their severities
5.1 General
A number of classes for climatic conditions (K), special climatic conditions (Z), biological
conditions (B), chemically active substances (C), mechanically active substances (S), and
mechanical conditions (M) are specified.
This classification allows for a number of possible combinations of environmental conditions
which bear upon products wherever geographically located. It represents the real situation
concerning worldwide conditions of storage due to local influences. For certain environmental
parameters, it has not yet been possible to specify quantitative severities.
For a given location or product, reference should be made to the total set of classes as defined
in 5.2 through 5.8, for example:
5K11/5Z2/5B1/5C2/5S5/5F1/5M5
5.2 Climatic conditions (K)
NOTE The classes defined in IEC 60721-3-5:1985 and IEC 60721-3-5:1997 have been replaced with
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