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 Several classes have been replaced by completely new classes based on the use of new information obtained from referenced technical reports.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.
The contents of the corrigendum of July 2023 have been included in this copy.

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.
Le contenu du corrigendum de juillet 2023 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 21-May-2019
• ICS: 19.040 - Environmental testing
• Technical Committee: TC 104 - Environmental conditions, classification and methods of test
• Drafting Committee: MT 19 - TC 104/MT 19
• Current Stage: PPUB - Publication issued
• Start Date: 22-May-2019
• Completion Date: 21-Jun-2019

Relations

• Corrected By: IEC 60721-3-4:2019/COR1:2023 - Corrigendum 1 - Classification of environmental conditions - Part 3-4: Classification of groups of environmental parameters and their severities - Stationary use at non-weatherprotected locations
• Effective Date: 05-Sep-2023
• Revises: IEC 60721-3-4:1995/AMD1:1996 - Amendment 1 - 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: 05-Sep-2023

Standards Content (Sample)

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

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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

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
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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.
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 the product specification, when referring to a certain class in IEC 60721-3
(all parts), to define whether the product is required to be capable of operating when being
exposed to the conditions described by the class.
The environmental classes may be used as a basis for the selection of design and test
severities with respect to the consequence of failure. Information contained in IEC 60721-3
(all parts) may be used 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.
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 may exist which require
consideration of severities that are not addressed in this document. The user of this document
should select the lowest classification necessary for covering the conditions of the intended
use.
5 Classification of groups of environmental parameters and their severities
5.1 General
Several 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 several possible combinations of environmental conditions which
bear upon products when installed in non-weatherprotected locations. It represents the real
situation concerning world-wide conditions of use due to local influences of open-air climate,
etc.
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 5.7, for example:
4K26/4Z3/4B3/4C2/4S12/4M10
5.2 Climatic conditions (K)
The classes defined in previous versions of this document have been replaced with new
classes as a result of recent efforts at collecting information regarding climatic conditions.
Those results are contained in technical reports referenced in this document.
At non-weatherprotected locations, the influence of special climatic conditions constitutes a
more significant share of the effects bearing upon a product and its functional parts than at
weatherprotected locations. Particularly the effects of temperature change, solar radiation,
precipitation, air velocity and wind-chill should be considered in this respect.
The severity of these effects may be influenced for instance by constructional details (sort
and thickness of material, colour of surface, sealing or breathing of casings or enclosures,
product heating, etc.) and by mounting details (selection of mounting site, consideration of
degree of exposure to prevailing wind and weather, etc.).
The climatic conditions specified for classes 4K23 to 4K27 refer to the non-weatherprotected
conditions where products may be used. These conditions have been experienced world-wide
over a long time period. The conditions should cover all normal cases, but not exceptional
events. These conditions are specified in Table 1. The interdependence of temperature to
relative humidity is shown in Annex A.
Sheltered non-weatherprotected locations
4K23 applies to sheltered non-weatherprotected locations in tropical, arid, temperate, and
cold climatic classification with the thermal effects from solar radiation encompassed
in the temperature.
4K24 applies to sheltered non-weatherprotected locations in the polar climate type with the
thermal effects from solar radiation encompassed in the temperature.
Open-air non-weatherprotected locations
4K25 applies to open-air locations in the tropical climatic classification.
4K26 applies to open-air storage in the arid and temperate climatic classifications.
4K27 applies to open-air storage in the cold and polar climatic classifications.

– 8 – IEC 60721-3-4:2019 © IEC 2019
5.3 Special climatic conditions (Z)
Parameters such as heat radiation, movement of the surrounding air, solar radiation, snow
load, and water from sources other than rain may occur with any severity in combination with
any of the other climatic conditions. Recommended values for these conditions are shown in
Table 2.
5.4 Biological conditions (B)
No quantitative severity has been specified for the following conditions. The specified
parameters of Table 3 are typical, but may not be complete.
4B1 applies to locations where mould growth is prevented, and physical controls are in
place to prevent attack by animals.
4B2 applies to locations where no controls are in place to prevent mould growth or
attacks by animals, except termites.
4B3 applies to locations where attacks by termites or similar fauna may occur.
5.5 Chemically active substances (C)
The contamination of the natural atmosphere is mainly caused by chemical emissions from
industrial activities, motor-driven vehicles, and heating systems. A further chemical influence
is caused by aerosols of sea and road salts. Contamination may affect the function and
materials of products. Additional details regarding the categorization of these conditions may
be found in ISO 9223.
5.6 Mechanically active substances (S)
Dust and sand are classified together, as the effects caused by these environmental
conditions are similar.
4S10 applies to locations where precautions have been taken to minimize the presence of
dust and sand.
4S11 applies to locations not situated in proximity to dust or sand sources and with no
precautions to minimize the ingress of dust or sand.
4S12 applies to locations near sand or dust sources, including urban areas and with no
precautions to minimize the ingress of dust or sand. It also applies to locations
situated in areas not subject to natural dust storms or significant industrial activity.
4S13 applies to locations which may be exposed to wind-driven dust and sand either due
to natural conditions or due to industrial activity producing blown sand or dust.
These conditions are specified in Table 4.
5.7 Mechanical conditions (M)
Mechanical conditions relate to the levels of vibration and shock that may exist at a usage
location, for example as a result of normal operations, nearby vehicular movement. These
conditions are specified in Table 5. See Annex B for the definition of seismic environment.
4M10 applies to locations experiencing insignificant levels of vibration and shock.
4M11 applies to non-weatherprotected locations experiencing low levels of vibration and
shock, such as those transmitted from air conditioning, machines or passing vehicles
in the vicinity.
4M12 applies to non-weatherprotected locations experiencing significant levels of vibration
and shock, such as those close to heavy machines or conveyor belts.

Table 1 – Classification of climatic conditions
Classification
Environmental parameter Unit Sheltered Open-air
4K23 4K24 4K25 4K26 4K27
°C +5 -50
Low air temperature −45 −50 −20
i i i
High air temperature °C +70 +70 +45 +50 +45
a
Low relative humidity % 4 4 30 4 10
a
High relative humidity % 100 100 100 100 100
a 3
Low absolute humidity g/m 0,2 0,003 6 0,1 0,003
a 3
High absolute humidity g/m 35 20 35 30 25
b
Rate of change of temperature °C/min 1,0 1,0 1,0 1,0 1,0
c
Low air pressure kPa 70 70 70 70 70
c
High air pressure kPa 106 106 106 106 106
2 h h l l l
Solar radiation W/m  1 090 1 090 1 090
f f
Heat radiation Not specified No No No
d d, f d, f f f f
Movement of surrounding air m/s 5,0 5,0 22 22 22
Condensation Not specified Yes Yes Yes Yes Yes
m g g
Precipitation (rain, snow, hail, etc.) Not specified Yes Yes Yes Yes Yes
g g
Rain intensity mm/min No No 15 15 15
Driving rain m/s No No 18 18 18
g g
Snow load kg/m No No No
e g g
Low rain temperature °C No No +5 +5 +5
j j j
Not specified Dripping Dripping
Water from sources other than rain
water water
k k k
Formation of ice and frost Not specified Yes Yes Yes Yes Yes
a
The low and high relative humidity levels are limited by the low and high absolute humidity. See Annex A.
b
Averaged over a period of 5 min.
c
The value of 70 kPa represents a limit for open-air conditions, normally at an altitude of 3 000 m. In some
geographical areas, open-air conditions may occur at higher altitudes. Conditions in mines are not considered.
If applicable, a special value may be selected from Table 2.
d
A cooling system based on non-assisted convection may be disturbed by adverse movement of surrounding
air.
e
This rain temperature should be considered together with high air temperature and solar radiation. The
cooling effect of the rain should be considered in connection with the surface temperature of the product.
f
If applicable, a special value may be selected from Table 2.
g
Applies only to wind-driven precipitation at sheltered locations.
h
Thermal effect of solar radiation is included in the temperature.
i
Thermal effect of solar radiation is not included in the temperature.
j
Sources of water other than rain are encompassed in driving rain.
k
Formation of frost can occur due to heat radiation to a clear sky.
L
From sea level.
M
See IEC 60721-2-2 for additional information.

– 10 – IEC 60721-3-4:2019 © IEC 2019
Table 2 – Classification of special climatic conditions
Environmental parameter Class Unit Special condition Z
Heat radiation 4Z1 No Negligible
4Z2 No Conditions of heat radiation, for
example, near heating systems
a
Wind, steady state 4Z4 m/s 30
4Z5 m/s 50
4Z11 m/s 67
Water from sources other than rain 4Z12 No Dripping water
4Z13 No Spraying water
4Z14 No Splashing water
Solar radiation 4Z15 W/m 500
4Z16 W/m 700
Snow load 4Z17 kg/m 100 (single snow storm)
4Z18 kg/m 240 (whole season)
Air pressure 4Z10 kPa 84 (approx. 1 500 m above sea level)
4Z19 kPa 62 (approx. 4 000 m above sea level)
a
Velocities are 10-min averages taken at a height of 10 m above ground.

Table 3 – Classification of biological conditions
Class
Biological parameter
4B1 4B2 4B3
Presence of mould, fungus, etc.
Presence of rodents and other animals
No Negligible
harmful to products
excluding termites including termites

Table 4 – Classification of mechanically active substances
Class
Environmental parameter Unit
4S10 4S11 4S12 4S13
Setting (sedimentary) dust mg/(m ⋅d) 6 6 Note 1 Note 2
No No 600 Note 2
Turbulent (suspended) dust mg/(m ⋅h)
mg/m 18
3 3
Windblown dust No 0,04 mg/m 1 mg/m
m/s 13
mg/m 18
3 3
Windblown sand No 0,04 mg/m 1 mg/m
m/s 13
NOTE 1 Encompassed within turbulent (suspended) dust.
NOTE 2 Encompassed within windblown dust.

Table 5 – Classification of mechanical conditions
Class
Environmental parameter Unit
4M10 4M11 4M12
Stationary vibration, random:
2 2
(m/s ) /Hz 0,01 0,1
acceleration spectral density No
Frequency range Hz 5 to 200 5 to 200
Shock m/s No No 20
– 12 – IEC 60721-3-4:2019 © IEC 2019
Annex A
(informative)
Interdependence of air temperature,
relative air humidity, and absolute air humidity
Annex A contains a climatogram (see Figure A.1) showing the interdependence of air
temperature, relative air humidity and absolute air humidity. For a given severity of low or high
absolute air humidity, the relevant severity of relative air humidity at a given air temperature
within the temperature range of a class may be found at the point where the curve for
constant absolute air humidity cuts the straight line for air temperature and relative air
humidity.
Figure A.1 – Climatogram of interdependence of air temperature,
relative air humidity, and absolute air humidity

Annex B
(informative)
Definition of seismic environment
For the general description and definition of the seismic excitation relay, see IEC 60721-2-6.
During an earthquake, electromechanical components and equipment are subjected to
motions that can overstress equipment frames, circuit boards, and connectors.
The seismic excitation which equipment experiences during an earthquake depends on
several parameters including the ground motion intensity, structural characteristics of a
building, elevation of the equipment in a building, and characteristics of the structures used to
support and house equipment.
The most common method for specifying seismic conditions taking into account all these
parameters is through the definition of a shock response spectrum (SRS); for the meaning of
SRS see IEC 60068-2-27. The SRS may be used to describe the motion that equipment is
expected to experience at its mounting during a postulated seismic event.
To define an SRS, it is necessary to define the base motion. The high frequency asymptotic
value of the acceleration of the response spectrum is normally called zero period acceleration
(ZPA) and represents the largest peak value of acceleration of the base motion.
In the absence of a detailed knowledge of the possible seismic motion, the ZPA value can be
obtained by the following formula (see IEC 60068-3-3):
ZPA= a= a×K××D G
fg
where:
a is the base acceleration;
f
a is the peak ground acceleration (PGA) that depends on the intensity of the earthquake;
g
K is the super-elevation factor that takes into account the amplification of the ground
acceleration resulting from the vibrational behaviour of buildings and structures;
D is the direction factor that takes into consideration possible intensity differences of the
seismic motion between the horizontal and vertical axes; and
G is the geometric factor; normally specified among testing parameters when single axis
excitation is used for testing to take into account the interaction, due to installation
location, along the different axes of the equipment of simultaneous multi-directional
input vibrations.
The peak ground acceleration, a , depends upon the seismicity of the zone where it is
g
expected that the equipment will be installed for in-service conditions.
Figure 5 in IEC 60721-2-6:1990 shows the map of seismic activity zones. Zone 4 corresponds
to the highest seismic activity areas, Zone 3 the next highest, and so on. Geographic areas
designated as Zone 0 represent no substantial seismic activity.
Table B.1 correlates the seismic zone with the expected magnitude given by different seismic
scales and the expected peak ground acceleration. The correspondence among the peak
ground acceleration, the seismic activity zone and the modified Mercalli index are taken from
IEC TS 62271-210.
– 14 – IEC 60721-3-4:2019 © IEC 2019
Table B.1 – Correlation of seismic zones with expected magnitudes
Peak ground acceleration (PGA) Modified Mercalli index
Seismic activity zone Richter scale
(m/s ) (MMI)
0,01 I 0 to 2
0,01 to 0,02 II 1 to 2
0,02 to 0,05 III 2 to 3
0,05 to 0,1 IV 3 to 4
0,1 to 0,2 V 4 to 5
0,2 to 0,5 VI 5 to 6
2 0,05 - 1 VII 5 to 7
3 1 to 2 VIII 6 to 8
2 to 5 IX 7 to 9
5 to 10 X
10 to 20 XI 8 or higher
more than 20 XII
Bibliography
IEC 60068-2-27, Environmental testing – Part 2: Tests – Test Ea and guidance: Shock
IEC 60068-3-3, Environmental testing – Part 3-3: Guidance – Seismic test methods for
equipments
IEC 60721-2 (all parts), Classification of environmental conditions – Part 2-X: Environmental
conditions appearing in nature
IEC 60721-1, Classification of environmental conditions − Part 1: Environmental parameters
and their severities
IEC 60721-2-1, Classification of environmental conditions − Part 2-1: Environmental
conditions appearing in nature − Temperature and humidity
IEC 60721-2-2, Classification of environmental conditions – Part 2-2: Environmental
conditions appearing in nature – Precipitation and wind
IEC 60721-2-3, Classification of environmental conditions – Part 2-3: Environmental
conditions appearing in nature – Air pressure
IEC 60721-2-4, Classification of environmental conditions – Part 2-4: Environmental
conditions appearing in nature – Solar radiation and temperature
IEC 60721-2-5, Classification of environmental conditions – Part 2-5: Environmental
conditions appearing in nature – Dust, sand, salt mist
IEC 60721-2-6:1990, Classification of environmental conditions – Part 2-6 Environmental
conditions appearing in nature – Earthquake vibration and shock
IEC 60721-2-9, Classification of environmental conditions – Part 2-9: Environmental
conditions appearing in nature – Measured shock and vibration data – Storage, transportation
and in-use
IEC 60721-3 (all parts), Classification of environmental conditions – Part 3-X: Classification of
groups of environmental parameters and their severities
IEC 60721-3-0, Classification of environmental conditions − Part 3: Classification of groups of
environmental parameters and their severities − Introduction
IEC 60721-3-3, Classification of environmental conditions – Part 3-3: Classification of groups
of environmental parameters and their severities – Stationary use at weather protected
locations
IEC TR 62130, Climatic field data including validation
IEC TR 62131-2, Environmental conditions – Vibration and shock of electrotechnical
equipment − Part 2: Equipment transported in fixed wing jet aircraft
IEC TR 62131-3, Environmental conditions – Vibration and shock of electrotechnical
equipment − Part 3: Equipment transported in rail vehicles
IEC TR 62131-4, Environmental conditions – Vibration and shock of electrotechnical
equipment − Part 4: Equipment transported in road vehicles

– 16 – IEC 60721-3-4:2019 © IEC 2019
IEC TR 62131-5, Environmental conditions – Vibration and shock of electrotechnical
equipment − Part 5: Equipment during storage and handling
IEC TS 62271-210, High-voltage switchgear and controlgear – Part 210: Seismic qualification
for metal enclosed and solid-insulation enclosed switchgear and controlgear assemblies for
rated voltages above 1 kV and up to and including 52 kV
ISO 9223, Corrosion of metals and alloys – Corrosivity of atmospheres – Classification,
determination and estimation
___________
– 18 – IEC 60721-3-4:2019 © IEC 2019
SOMMAIRE
AVANT-PROPOS . 19
1 Domaine d'application . 21
2 Références normatives . 21
3 Termes et définitions . 21
4 Généralités . 22
5 Classification des groupements des agents d'environnement et de leurs sévérités . 23
5.1 Généralités . 23
5.2 Conditions climatiques (K) . 23
5.3 Conditions climatiques spéciales (Z) . 24
5.4 Conditions biologiques (B) . 24
5.5 Substances chimiquement actives (C) . 24
5.6 Substances mécaniquement actives (S) . 24
5.7 Conditions mécaniques (M) . 25
Annexe A (informative) Interdépendance de la température de l'air, de l’humidité
relative de l'air et de l’humidité absolue de l’air . 28
Annexe B (informative) Définition de l’environnement sismique . 29
Bibliographie . 31

Figure A.1 – Climatogramme de l'interdépendance de la température de l'air, de
l’humidité relative de l'air et de l’humidité absolue de l’air . 28

Tableau 1 – Classification des conditions climatiques . 25
Tableau 2 – Classification des conditions climatiques spéciales. 26
Tableau 3 – Classification des conditions biologiques . 27
Tableau 4 – Classification des substances mécaniquement actives . 27
Tableau 5 – Classification des conditions mécaniques . 27
Tableau B.1 – Corrélation des zones sismiques avec les magnitudes attendues . 30

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
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

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