IEC 62440:2008

Electric cables with a rated voltage not exceeding 450/750 V - Guide to use

Provides general guidance for the safe use of electric cables with a rated voltage not exceeding 450/750 V. It is applicable to those cables that are specified in IEC 60227 and IEC 60245. The guidance given in this standard can also be applicable to low-voltage cables of a similar type to those specified in IEC 60227 and IEC 60245 but not specifically mentioned in those standards. In such cases, it is advisable to seek additional advice from the cable manufacturer.

Câbles électriques avec une tension assignée n'excédant pas 450/750 V - Guide d'emploi

Fournit des lignes directrices pour l'emploi sûr des câbles électriques avec une tension assignée n'excédant pas 450/750 V. Il est applicable aux câbles spécifiés dans la CEI 60227 et la CEI 60245. Les lignes directrices données dans la présente norme peuvent également s'appliquer aux câbles basse tension d'un type similaire à ceux spécifiés dans la CEI 60227 et la CEI 60245, mais dont il n'est pas fait spécifiquement mention dans ces normes. Dans de tels cas, il est souhaitable de demander un conseil supplémentaire au fabricant de câbles.

General Information

• Status: Published
• Publication Date: 06-Feb-2008
• ICS: 29.060.20 - Cables
• Technical Committee: TC 20 - Electric cables
• Drafting Committee: WG 17 - TC 20/WG 17
• Current Stage: PPUB - Publication issued
• Start Date: 07-Feb-2008
• Completion Date: 29-Feb-2008

Overview

IEC 62440:2008 is an international standard developed by the International Electrotechnical Commission (IEC) that provides comprehensive guidance on the safe use of electric cables with rated voltages not exceeding 450/750 V. This standard applies primarily to cables specified under IEC 60227 (PVC insulated cables) and IEC 60245 (rubber insulated cables). It is also relevant for similar low-voltage cables not explicitly mentioned in these standards, recommending consultation with manufacturers for cases elsewhere.

By addressing core aspects of cable selection, installation, operation, and safeguarding, IEC 62440 enhances electrical safety in buildings, industrial settings, and various installations worldwide. Adhering to this standard helps ensure compliance with international safety practices, supports efficient cable performance, and reduces risks to people and property.

Key Topics

IEC 62440:2008 covers a variety of crucial areas to promote the safety and longevity of low-voltage electric cables:

• General cable selection: Determining suitability for voltage, current, installation environment, and operational conditions.
• Safety instructions: Requirements for safe installation, use, protection, and maintenance to prevent hazards.
• Environmental considerations: Adapting cable choice to withstand temperature variation, moisture, chemical exposure, mechanical stress, radiation, fauna, and flora.
• Fixed and flexible cable guidelines: Distinction between requirements for fixed wiring and flexible cables/cords, including recommended support spacing and usage types.
• Limiting conditions: Addressing critical factors such as voltage ratings, current-carrying capacity, thermal effects, fire characteristics, and mechanical stress management, including tension, bending, compression, and torsion.
• Installation best practices: Recommendations for supporting, handling, and protecting cables against possible damage during and after installation.
• Verification and maintenance: Emphasis on initial and periodic checks, as well as appropriate packaging, storage, and transportation of cables to maximize performance and safety.

Applications

IEC 62440 finds practical application across a broad spectrum of industries and environments where low-voltage electric cables (not exceeding 450/750 V) are used. Key application areas include:

• Residential and commercial buildings: Guidance on internal wiring and electrical distribution, contributing to safe and reliable power infrastructure.
• Construction sites and temporary buildings: Recommendations for appropriate cable selection and installation in provisional setups.
• Industrial facilities: Ensuring compliance in process plants, equipment connections, and machinery installations.
• Public spaces: Reducing fire and electrical hazards in hotels, hospitals, offices, and other populated buildings.
• Portable and mobile equipment: Appropriate use of flexible cables for appliances, tools, and temporary setups, with considerations for mechanical stress and environmental challenges.
• Outdoor and special environments: Providing insights into cable behavior under diverse environmental conditions, including robustness against UV radiation, rain, or pollution.

Implementing IEC 62440 guidelines helps minimize risks related to electrical faults, fire propagation, and mechanical failures, while also supporting the selection of cables that meet both legislative and operational requirements in various sectors.

Related Standards

• IEC 60227: Specifies requirements for polyvinyl chloride (PVC) insulated cables of rated voltages up to and including 450/750 V.
• IEC 60245: Covers rubber insulated cables for similar voltage ratings, including specific application types like welding cables.
• IEC 60050-461: International Electrotechnical Vocabulary – Electric cables.
• IEC 60364 (all parts): Central reference for low-voltage electrical installations, particularly relevant for cable selection and installation in buildings.
• IEC 60335-1: General safety requirements for household and similar electrical appliances.
• IEC 60287: Methods for calculation of current ratings in electric cables.
• IEC 60079: Guidance on electrical apparatus for explosive atmospheres, relevant when selecting cables for hazardous areas.

Consulting these associated standards alongside IEC 62440 ensures that all technical, safety, and regulatory aspects of low-voltage electric cable usage are thoroughly addressed, leading to higher safety and operational assurance.

Standards Content (Sample)

IEC 62440
Edition 1.0 2008-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electric cables with a rated voltage not exceeding 450/750 V – Guide to use

Câbles électriques avec une tension assignée n’excédant pas 450/750 V – Guide
d’emploi
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IEC 62440
Edition 1.0 2008-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electric cables with a rated voltage not exceeding 450/750 V – Guide to use

Câbles électriques avec une tension assignée n’excédant pas 450/750 V – Guide
d’emploi
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
T
CODE PRIX
ICS 29.060.20 ISBN 2-8318-9570-7

– 2 – 62440 © IEC:2008
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.7
2 Normative references.7
3 Terms and definitions .7
4 Safety.8
4.1 General .8
4.2 Selection and installation .8
4.3 Fixed cables .9
4.4 Flexible cables or cords .9
5 Limiting conditions .11
5.1 General .11
5.2 Voltage.11
5.3 Current-carrying capacity.11
5.4 Thermal effects .12
5.5 Fire characteristics .13
5.6 Mechanical stress.14
5.6.1 General .14
5.6.2 Tension .14
5.6.3 Bending .14
5.6.4 Compression .16
5.6.5 Twisting/torsion.16
5.7 Compatibility.17
5.8 Dynamic stresses (electromechanical stress).17
6 Initial and periodic verifications .17
7 Packaging, storage and handling/transportation .17
7.1 Packaging .17
7.2 Storage .18
7.2.1 Risk of moisture.18
7.2.2 Temperature conditions .18
7.3 Handling/transportation.18

Annex A (informative) Classes of external influence (environmental conditions) .19
Annex B (informative) Types of usage .21
Annex C (informative) Classes of duty.22

Bibliography .24

Figure 1 – Definition of internal bending radius .15

62440 © IEC:2008 –3–
Table 1 – Spacing of supports for non-armoured cables in accessible positions .9
Table 2 – Examples of maximum permitted voltages against rated voltage of cable .11
Table 3 – Minimum recommended bending radii at cable temperatures of (20 ± 10) °C .16
Table A.1 – Classes of external influence (environmental conditions).19

– 4 – 62440 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRIC CABLES WITH A RATED VOLTAGE
NOT EXCEEDING 450/750 V –
GUIDE TO USE
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
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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
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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 62440 has been prepared by IEC technical committee 20: Electric
cables.
The text of this standard is based on the following documents:
FDIS Report on voting
20/919/FDIS 20/929/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In some countries legislation may limit the use of certain cable types, and may define additional
requirements for cable installation practice.

62440 © IEC:2008 –5–
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – 62440 © IEC:2008
INTRODUCTION
This International Standard provides guidance for equipment manufacturers, installers and
end-users on the properties of low-voltage electric cables, and the limitations that are deemed
to be necessary in order to safeguard life, buildings and goods.
The information is given in the form of limiting values and is illustrated by examples which are
not exhaustive but which indicate ways in which safety can be obtained.
Additional information on installation practice is given in the IEC 60364 series.

62440 © IEC:2008 –7–
ELECTRIC CABLES WITH A RATED VOLTAGE
NOT EXCEEDING 450/750 V –
GUIDE TO USE
1 Scope
This International Standard provides general guidance for the safe use of electric cables with a
rated voltage not exceeding 450/750 V. It is applicable to those cables that are specified in
IEC 60227 and IEC 60245.
The guidance given in this standard can also be applicable to low-voltage cables of a similar
type to those specified in IEC 60227 and IEC 60245 but not specifically mentioned in those
standards. In such cases, it is advisable to seek additional advice from the cable manufacturer.
NOTE Whilst this International Standard, which offers guidelines to the user, is a voluntary standard, those who
choose to use it, or who claim conformance to it, must follow the advice contained therein, e.g. with regard to
certain bending radii or certain clip spacings, etc. Notwithstanding this, national laws and regulations (especially
those relating to selection and installation of cables via IEC 60364), will always take priority.
2 Normative references
The following referenced documents are indispensable for the application 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 60050-461, International Electrotechnical Vocabulary – Part 461: Electric cables
IEC 60245-6, Rubber insulated cables – Rated voltages up to and including 450/750 V – Part 6:
Arc welding electrode cables
IEC 60287(all parts), Electric cables – Calculation of the current rating
IEC 60335-1, Household and similar electrical appliances – Safety – Part 1: General
requirements
IEC 60364 (all parts), Low-voltage electrical installations
IEC 60364-5-52, Electrical installations of buildings – Part 5-52: Selection and erection of
electrical equipment – Wiring systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-461 and in the
IEC 60364 series, as well as the following, apply.
3.1
internal wiring
wiring mechanically protected by being enclosed within a casing of equipment or by other
equivalent means
– 8 – 62440 © IEC:2008
4 Safety
4.1 General
Safety of a cable means that the product does not present an unacceptable risk of danger to
life or property whilst being used in its intended manner.
The duration of acceptable performance of a particular type of cable depends upon:
– the type of use,
– installation, or
– electrical apparatus,
and on the particular combination of influences that the above might incur. For example, the
duration of acceptable performance considered as reasonable for a cable used in a fixed
installation for the distribution of electricity in a building is more than that for a flexible cord.
Cables shall not be buried directly in the ground, and unless otherwise stated, shall not be
used for any purpose other than the transmission and distribution of electricity.
The test methods and test parameters described in the IEC standards referred to in Clause 1
are only for the purposes of checking design with respect to safety and quality assurance. They
do not necessarily indicate that the cables are suitable for service under conditions equivalent
to the test conditions.
4.2 Selection and installation
4.2.1 All conductors and cables shall be selected so as to be suitable for the voltages and
currents likely to occur, and under all conditions which are anticipated in the equipment or
installations or for the part in which they are to be used.
4.2.2 Cables shall be so constructed, installed, protected, used and maintained as to prevent
danger so far as it is reasonably practicable.
4.2.3 Cables shall be selected so that they are suitable for the intended operating conditions
and equipment classification. Examples of operation conditions include:
a) voltage;
b) current;
c) protective measures;
d) grouping of cables;
e) method of installation;
f) accessibility.
4.2.4 Cables shall be selected so that they are suitable for any external influences which
might exist. Cables should not be installed under any of these conditions unless they are of a
type specifically designed to withstand such conditions. Examples of external influences
include:
a) ambient temperature;
b) presence of rain, steam or accumulation of water;
c) presence of corrosive, chemical or polluting substances;
d) mechanical stresses (such as through holes or sharp edges in metal work);
e) fauna (such as rodents);
f) flora (such as mould);
62440 © IEC:2008 –9–
g) radiation (such as sunlight).
The colour of the cable is an important factor with regard to solar radiation. Black gives a
higher degree of protection against solar radiation than a light colour.
Classes of external influence are shown in Annex A.
Annex B gives an explanation of the different types of usage (i.e. indoor/outdoor).
4.3 Fixed cables
4.3.1 Cables shall not be installed in contact with, or close to, hot surfaces, unless they are of
a type intended for such conditions.
4.3.2 Cables shall be supported adequately. The recommended maximum spacing of
supports is given in Table 1. In deciding the actual spacing, the mass of the cable between the
supports shall be taken into account so that the limiting value of tension (see 5.6.2) is not
exceeded. The cable shall not be damaged by any mechanical restraint used for its support.
In the case of single-core cables, the spacing also depends on the dynamic forces due to a
short-circuit current; the manufacturer’s recommendations shall be observed (see 5.8).
Cables which have been in use can be damaged if they are disturbed. This can arise from the
effect of natural ageing on the physical properties of the materials used for cable insulation and
sheathing which can ultimately result in hardening of these materials.
Table 1 – Spacing of supports for non-armoured cables in accessible positions
b
Overall diameter (D) Maximum spacing of supports
a
of cable mm
General In caravans
mm
Horizontal Vertical Horizontal Vertical
250 400 150 150
D ≤9
300 400 150 150
9 15 c
20 a
For flat cables this is taken as the measurement of the major axis.
b
The spacings stated for horizontal runs may also be applied to runs at an angle of more than 30° from the
vertical. For runs at an angle of 30° or less than the vertical, the vertical spacings are applicable.
c
For the spacing of supports for cables of overall diameter exceeding 40 mm, and for single core cables having
conductors of cross-sectional area 300 mm and larger, the manufacturer’s recommendations shall be
observed.
4.4 Flexible cables or cords
4.4.1 Flexible cables or cords shall be used for connections to all mobile equipment.
The length of such cables should not be so great as to prevent the short-circuit protective
device from operating correctly (see 5.3). Such cables should also be of a minimum practical
length to reduce the risk of mechanical damage.
4.4.2 Flexible cables and cords shall be selected and used with due reference to the
appropriate class of duty.
Annex C gives information on classes of duty.

– 10 – 62440 © IEC:2008
4.4.3 Where thermoplastic flexible cables and cords are acceptable, consideration shall be
given to the use of extensible leads as a means of limiting the length of the connection.
4.4.4 Multicore control cables, if installed so that they are continually flexed, shall be
protected in a manner which minimizes the possibility of abrasion, cutting and sharp bends.
4.4.5 Flexible cables and cords shall not be used as fixed wiring unless they are contained in
an enclosure affording mechanical protection, with the following two exceptions:
a) final connection to fixed equipment when the duty type of the cable is at least ordinary duty
or higher;
b) fixed installations in temporary buildings when the duty type of the cable is heavy duty.
4.4.6 Exposed lengths of flexible cable or flexible cord used as final connections to fixed
equipment shall be as short as practicably possible and shall be directly connected to the fixed
wiring in a manner that is appropriate to the equipment and the method of termination.
4.4.7 Flexible cables or cords shall not be subject to excessive tension (see 5.6.2), crushing,
abrasion, torsion and kinking, particularly at the inlet of the appliance and at the point of
connection to the fixed wiring. They shall not be damaged by any strain relief or clamping
device.
4.4.8 Flexible cables or cords shall not be placed under carpets or other floor coverings,
where there is:
a) any risk of thermal insulating effects, leading to excessive temperature rise (see 5.4,1 point
a));
b) any risk of damage due to furniture or equipment resting on them or traffic passing over
them.
4.4.9 Flexible cables or cords shall be prevented from being in contact with or close to hot
surfaces, unless they are of a type intended for such conditions. Because of the relative low
melting temperature of thermoplastic insulated and/or sheathed cables or cords, very careful
consideration of the temperatures involved shall be made before using this type of cable. PVC-
covered cables shall not be used for welding (this includes both industrial arc welding and
hobby welding). Only the cross-linked rubber cables specified in IEC 60245-6 shall be used for
such purposes, as they are designed to resist the hot particles that are commonly generated
during welding.
4.4.10 When flexible cables or cords are required for use outdoors, whether for intermittent,
temporary or permanent usage, they shall only be used when the ambient temperature is in the
range of 5 °C to 40 °C. If a cable is required to work outside of this temperature range, the
cable manufacturer shall be consulted for guidance. Flexible thermoplastic cables or cords are
unsuitable for permanent use outdoors and shall not be used for temporary or intermittent
outdoor use, unless the ambient temperature is above 5 °C.
4.4.11 Non-sheathed cords shall not be used for connection to any Class II appliance (as
defined in IEC 60335-1), for any extension cord or for the replacement of any sheathed cable
type.
4.4.12 Flexible cables shall not be used in deep mining operations, in quarrying, or on
moveable equipment such as cranes with spring-loaded reeling devices.
4.4.13 Flexible thermoplastic cables and cords are not necessarily suitable for the
manufacture of extensible leads.

62440 © IEC:2008 –11–
5 Limiting conditions
5.1 General
The influence of all factors as outlined in 5.2 to 5.8 shall be considered in combination, not
separately.
5.2 Voltage
The rated voltage of a cable is the reference voltage for which the cable is designed.
The rated voltage in an alternating current system, is expressed by the combination of two
values U /U, expressed in volts, where:
a) U is the r.m.s. value between any insulated conductor and “earth” (metal covering of the
cable or the surrounding medium);
b) U is the r.m.s. value between any two phase conductors of a multicore cable or of a system
of single core cables.
In an alternating current system, the rated voltage of a cable or cord shall be at least equal to
the nominal voltage of the system for which it is intended. This condition applies to the values
of both U and U.
In a direct current system, the maximum permanent operating voltage of the system is stated in
Table 2.
Table 2 – Examples of maximum permitted voltages against rated voltage of cable
Rated voltage of cable Maximum permanent permitted operating voltage of the system
a.c. 3-phase a.c. d.c.
Conductor- Conductor- Conductor- Conductor-
U /U
earth conductor earth conductor
V U max (V) V V
U max (V)
a
300/300 320 320 410 410
300/500 320 550 410 820
450/750 480 825 620 1 240
a
Single phase power system only.

5.3 Current-carrying capacity
5.3.1 The cross-sectional area of every conductor shall be such that its current-carrying
capacity is not less than the maximum sustained current which will normally flow through it.
5.3.2 The limiting temperature to which the current-carrying capacity is related shall not
exceed that appropriate to the type of cable insulation or sheath concerned.
5.3.3 The current-carrying capacities for flexible cables, cords and fixed wiring shall be in
accordance with IEC 60364-5-52 or, where not available, reference shall be made to the cable
manufacturer.
The values given in IEC 60364-5-52 for the particular cable type and size have been
determined such that the limiting temperatures of the cable are not exceeded, under the

– 12 – 62440 © IEC:2008
particular installation conditions given, when the cables are continuously loaded (100 % load
factor) with current having an alternating frequency of 50 Hz or 60 Hz.
If current ratings for a particular cable type are not included in IEC 60364-5-52, ratings can be
derived from IEC 60287 or reference made to the cable manufacturer.
For arc welding cables, the current-carrying capacities and the associated voltage drop figures
shall be obtained from the cable manufacturer.
5.3.4 In the case of soft soldered joints or terminations, the temperature for the conductor
under short-circuit conditions shall be not more than 160 °C.
5.3.5 Tinned copper conductors shall not be used at temperatures above 200 °C, even under
fault conditions, because of the risk of mutual adhesion.
5.3.6 The method of installation used for the cable affects its current-carrying capacity and
due account shall be taken of this. Correction factors for quoted current-carrying capacities are
sometimes available for particular conditions such as:
a) ambient temperature;
b) cable grouping;
c) type of overcurrent protection;
d) presence of thermal insulation;
e) reeled/drummed cables;
f) frequency of supply (if different from 50 Hz or 60 Hz, etc.);
g) effect of harmonics.
5.3.7 The selection of the cross-sectional area of any conductor shall not be based on
current-carrying capacity alone. Account shall also be taken of:
1) electric shock;
2) thermal effects;
3) overload and short-circuit current;
4) voltage drop;
5) mechanical strength;
taking particular account of influences such as:
− limiting temperatures for terminals of equipment, busbars or bare conductors;
− limiting short-circuit temperatures;
− the carrying of current by the neutral conductor, e.g. as resulting from the presence of
significant harmonic current in a three-phase circuit;
− electromagnetic effects;
− reduction of heat dissipation;
− size of the circuit protective conductor under fault conditions;
− solar or infra-red radiation.
This list is not exhaustive. Other influences might arise for particular installations.
5.4 Thermal effects
5.4.1 The maximum continuous operating temperature limits of the individual types of cables
are given in IEC 60227 and IEC 60245. The values given shall not be exceeded by any

62440 © IEC:2008 –13–
combination of the heating effect of current in the conductors and the ambient conditions.
Particular account shall be taken of the following.
a) Cables in free air shall be installed so that the natural air convection is not impeded. When
cables are covered or embedded in thermal insulation, or when the heat dissipation is
impeded by other means, it is essential that the current-carrying capacity is reduced by an
appropriate factor. This factor can be as low as 0,5.
b) The temperature of cable sheaths can be significantly higher than the ambient
temperatures where the cables are subjected to radiation, e.g. solar or infra-red. Where
these situations cannot be avoided, their effect shall be taken into account in assessing the
current-carrying capacity or the temperature of the cable relative to the limiting temperature
and its service life.
c) Account shall be taken of the temperatures occurring within equipment, appliances,
luminaires and at their terminals, in selecting the types of cables to be used in them and
connected thereto.
d) Exposure of thermoplastic-insulated cables to temperatures greater than those given in
IEC 60364-5-52, even for short periods, can cause the insulation to soften. Account shall
be taken of this effect, particularly when mechanical stress is also an influence.
The minimum ambient temperature for all cable types is 5 °C, and if a cable is required to work
below this temperature, the cable manufacturer shall be consulted for guidance. All insulation
and sheath materials used for cables become progressively stiffer as their temperature is
lowered below the normal ambient temperature to the point where they become brittle.
5.4.2 Cables shall be selected, located and installed such that their intended heat dissipation
is not inhibited and they do not present a fire hazard to adjacent materials.
5.4.3 Where the surface of the cable is liable to exceed 50 °C, the cable shall be located or
guarded in such a way as to prevent contact with persons or animals.
Cable surface temperatures above this temperature can cause involuntary reaction in the event
of contact with exposed skin.
5.4.4 Account shall be taken of the effect of heat generated by the passage of current through
the conductor on the material of which it is made and on the material used in making joints or
terminations.
5.5 Fire characteristics
5.5.1 Cables can provide a source of fuel and means of propagating a fire, and the insulation
and sheath materials of burning cables can give rise to smoke and to toxic and corrosive
fumes. Where this could constitute a hazard, and particularly where it is necessary to ensure
safe evacuation of the premises, e.g. in public buildings, offices, hotels, hospitals, etc., the
guidance of the cable manufacturer shall be obtained to select cables to minimize the hazard.
The use of a fire safety engineering approach shall also be considered.
National legislation may exist which specifies the detailed requirements that have to be met.
5.5.2 Guidance shall be sought in selecting cables required to maintain the integrity of
electrical circuits when this is necessary for the safety of life and property in the case of fire.
5.5.3 When a cable is to be used in the presence of explosive or flammable atmospheres,
guidance shall be sought in selecting suitable cables.
Guidance is available from cable manufacturers; see also IEC 60079.

– 14 – 62440 © IEC:2008
5.6 Mechanical stress
5.6.1 General
In assessing the potential risk of mechanical damage to cables, account shall be taken of any
mechanical strains likely to be imposed during the normal process of installation of cables.
5.6.2 Tension
The tension applied to a cable shall not exceed the following values of tensile stress per
conductor, subject to a total maximum tensile force of 1 000 N, unless otherwise agreed by the
cable manufacturer:
a) 50 N/mm for non-flexible cables during installation;
b) 15 N/mm for flexible cables under static tensile stress, and for non-flexible cables in
service in fixed circuits.
NOTE A mass of 1 kg is approximately equal to 10 N.
In circumstances where a stress exceeding these values would result, a separate stress-
bearing member or device shall be used. The method of attaching such a member or device to
the cable shall be such that the cable is not damaged.
In circumstances where flexible cables are under dynamic stress (including those due to
inertia, e.g. reeling drums) the permissible tensions or fatigue life shall be agreed between the
design engineer and the cable manufacturer.
Where cables are installed vertically, without intermediate support, and are inaccessible and
unlikely to be moved or disturbed, they shall be supported at the top of the run such that the
internal radius of the resultant bend is not less than the appropriate minimum bending radius
for normal use according to Table 3. The unsupported vertical length shall not exceed 5 m.
5.6.3 Bending
The internal bending radii (R) (as shown in Figure 1) for different types of cable shall, under
normal circumstances, be not less than those given in Table 3.
Care shall be taken when stripping the insulation to ensure that no damage occurs to the
conductor, since this will severely affect the bending radii.
The bending radii (R) recommended are for ambient temperatures of (20 ± 10) °C. For
temperatures outside these limits, the cable manufacturer’s recommendations shall be
followed.
For flexible cables and cords, particularly at terminations and at the point of entry of moveable
appliances, it can be necessary to use a device which ensures that the cable is not bent to an
internal bend radius less than that recommended in Table 3. It is necessary to prevent the
cable being flexed significantly too close to any internal and/or external anchorage point. If a
cord guard or other device is used, it shall not prevent internal movement of the cores of the
cable within the device.
62440 © IEC:2008 –15–
R
IEC  005/08
Key
R internal bending radius
Figure 1 – Definition of internal bending radius

– 16 – 62440 © IEC:2008
Table 3 – Minimum recommended bending radii at cable temperatures of (20 ± 10) °C
Minimum bending radius
Cable Cable Cable Cable
diameter diameter diameter diameter
Cable type
mm mm mm mm
≤ 8 >8 ≤ 12 >12 ≤ 20 > 20
Cable for fixed installations:

Normal use 4 D 5 D 6 D 6 D
Careful bending at termination 2 D 3 D 4 D 4 D
Flexible cables (thermoplastic, e.g. PVC):
Fixed installation 3 D 3 D 4 D 4 D
Free movement 5 D 5 D 6 D 6 D
a
At inlet of portable appliance or mobile equipment 5 D 5 D 6 D 6 D
b
Under mechanical load 9 D 9 D 9 D 10 D
c
Festooned 10 D 10 D 11 D 12 D
b
Repeated reeling 7 D 7 D 8 D 8D
b
Deflected by pulleys 10 D 10 D 10 D 10 D
Flexible cables (thermosetting, e.g. rubber):
Fixed installation 3 D 3 D 4 D 4 D
Free movement 4 D 4 D 5 D 6 D
a
At inlet of portable appliance or mobile equipment 4 D 4 D 5 D 6 D
b
Under mechanical load 6 D 6 D 6 D 8 D
c
Festooned 6 D 6 D 6 D 8 D
b
Repeated reeling 6 D 6 D 6 D 8 D
b
Deflected by pulleys 6 D 8 D 8 D 8 D
D = the overall diameter of round cables or the smaller dimension of flat cables.
a
No mechanical load on the cable.
b
See 5.6.2 with regard to dynamic stress.
c
As in gantry cranes.
5.6.4 Compression
A cable shall not be compressed to such an extent as to cause damage.
None of the cables in IEC 60227 and IEC 60245 are intended to be compressed.
5.6.5 Twisting/torsion
Flexible cables are generally not designed to be twisted about the longitudinal axis.
In installations where it is not possible to avoid such twisting, the design of the flexible cable
and the installation arrangements shall be agreed between the designers of the installation and
the manufacturers of the cable.
For design purposes the following recommendations shall apply:

62440 © IEC:2008 –17–
a) Where the normal mode of operation requires infrequent rotation through an arc of up to
360° in either direction, the distance between the clamping supports of the cable shall be
not less than 50 times the largest cable diameter in the cable run.
b) Where the normal mode of operation requires frequent rotation through an arc of up to 360°
in either direction, the distance between the clamping supports of the cable shall be not
less than 100 times the largest cable diameter in the cable run.
Where cables designed specially for these purposes are used, the above ratios may be
reduced to 25 times and 50 times, respectively.
5.7 Compatibility
5.7.1 The possibility of interference, either mechanical or electrical, between adjacent circuits
shall be avoided.
5.7.2 Account shall be taken of the effect of heat given out by cables, and the
chemical/physical effect of materials used in their construction, on materials adjacent to which
they are installed, e.g. construction materials, decorative materials, cable enclosures and
supports.
5.7.3 The interaction of adjacent materials with the materials used in the construction of
cables shall be taken into account, e.g. the absorption of plasticizer from PVC cables by some
materials used for thermal insulation, wiring accessories and appliances.
5.8 Dynamic stresses (electromechanical stress)
Account shall be taken of the possibility of damage to cables and their supports due to the
disruptive effects of the electromechanical forces caused by any current which the cables
might have to carry in service, including short-circuit currents.
6 Initial and periodic verifications
Cables liable to be touched shall be inspected along their route and, if necessary, checked by
measurements at the end of the installation and periodically during operation.
Cables for fixed installations, or for fixed or transportable equipment, shall be inspected
periodically, and every time there is a possibility that the cable has been damaged by internal
(overvoltage, overcurrents) or external stresses. If the cable shows a visible change of external
appearance it shall either be repaired, through suitable devices and by skilled persons, or
replaced.
Cables for portable or hand-held equipment shall be inspected periodically. If the cable shows
any sign of wear, damage or visible change of external appearance, it shall be replaced.
7 Packaging, storage and handling/transportation
7.1 Packaging
Cables are normally delivered to the user either on drums, reels, in coils or as cut lengths in
non-tangle packaged units. They are normally labelled to identify the cable type, size and
voltage.
– 18 – 62440 © IEC:2008
7.2 Storage
7.2.1 Risk of moisture
Cables not intended for use outdoors shall be stored indoors in dry locations. Some types of
cords are particularly susceptible to damage due to moisture. Only cables having their ends
sealed, so as to prevent the penetration of moisture, and which are suitably packed, may be
stored outdoors. If there is any doubt as to the suitability of cables for storage out of doors, the
cable manufacturer shall be consulted.
7.2.2 Temperature conditions
During storage, the cable temperature shall not exceed the recommended maximum storage
temperature of 40 °C, or be lower than the recommended minimum installation temperature of
5 °C. A cable manufacturer may state a higher maximum storage temperature and a lower
minimum installation temperature for particular cable types.
7.3 Handling/transportation
During handling or transportation, care shall be taken to minimize any mechanical stress, in
particular vibration, impact, shock, bending and torsion. If the cable temperature falls below the
minimum installation temperature, or if it exceeds the maximum storage temperature given in
7.2.2, then additional precautions shall be taken as the likelihood of damage to the cable is
increased. Additional advice can be obtained from the cable manufacturer.

62440 © IEC:2008 –19–
Annex A
(informative)
Classes of external influence (environmental conditions)

A coding system for cables classifying external influences according to degree of risk is given
in Table A.1 (extract from IEC 60364-5-51:2005, Table 51A).
NOTE IPX refers to IEC 60529.
Table A.1 – Classes of external influence (environmental conditions)
Environmental
Code Classification Characteristics
condition
Water AD1 Negligible Probability of presence of water is negligible.
Location in which the walls do not generally show traces of water
but may do so for short periods, for example in the form of vapour
which good ventilation dries rapidly
AD2 Free falling Probability of vertically falling drops.
drops
Location in which water vapour occasionally condenses as drops or
where steam may occasionally be present.
IPX1 or IPX2
AD6 Waves Possibility of water waves.
Seashore locations such as piers, beaches, quays, etc.
IPX6
AD7 Immersion Possibility of intermittent, partial or total covering of water.
Locations which may be flooded and/or where the equipment is
immersed as follows:
– Equipment with a height of less than 850 mm is located in such
a way that its lowest point is not more than 1 000 mm below the
surface of the water
– Equipment with a height equal to or greater than 850 mm is
located in such a way that its highest point is not more than
150 mm below the surface of the water.
IPX7
AD8 Submersion Possibility of permanent and total covering by water.
Locations such as swimming pools where electrical equipment is
permanently and totally covered with water under a pressure greater
than 10 kPa.
IPX8
Corrosive or AF3 Intermittent or Intermittent or accidental subjection to corrosive or polluting
polluting accidental substances being used or produced.
sub
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