SIST IEC 60364-5-51:2006

NORME CEI
INTERNATIONALE
IEC



60364-5-51
INTERNATIONAL


Cinquième édition
STANDARD

Fifth edition

2005-04


Installations électriques des bâtiments –
Partie 5-51:
Choix et mise en œuvre des matériels
électriques – Règles communes

Electrical installations of buildings –
Part 5-51:
Selection and erection of electrical
equipment – Common rules

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For price, see current catalogue

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60364-5-51  IEC:2005 – 3 –
CONTENTS
FOREWORD.5

510 Introduction .9
511 Compliance with standards .13
512 Operational conditions and external influences .13
513 Accessibility.41
514 Identification .41
515 Prevention of mutual detrimental influence .43
516 Measures related to protective conductor currents .45

Annex A (informative) Concise list of external influences .47
Annex B (Annex B of IEC 60364-3) (informative) Interdependence of air temperature,
relative air humidity and absolute air humidity.51
Annex C (Annex C of IEC 60364-3) (normative) Classification of mechanical conditions .71
Annex D (Annex D of IEC 60364-3) (normative) Classification of macro-environments.73
Annex E (informative) Permissible protective conductor currents for equipment.75
Annex F (informative)  IEC 60364 – Parts 1 to 6: Restructuring .81

Bibliography.89

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60364-5-51  IEC:2005 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTRICAL INSTALLATIONS OF BUILDINGS –

Part 5-51: Selection and erection of electrical equipment –
Common rules


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
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
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60364-5-51 has been prepared by IEC technical committee 64:
Electrical installations and protection against electric shock.
This fifth edition of IEC 60364-5-51 cancels and replaces the fourth edition published in 2001
and constitutes a technical revision.
The document 64/1438/FDIS, circulated to National Committees as Amendment 1, led to the
publication of the new edition.

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60364-5-51  IEC:2005 – 7 –
The main changes with respect to the previous edition are listed below:
− corrections of misprints in Table 51 based on Table 321 derived from the old Part 3;
− introduction of a new Clause 516 dealing with measures for mitigation of protective
conductor currents;
− introduction of an informative Annex B extracted from IEC 61140 in Annex E of this
standard. Annex B of IEC 61140 deals with protective conductor currents.
The text of this standard is based on the following documents:
FDIS Report on voting
64/1438/FDIS 64/1460/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.
IEC 60364 consists of the following parts, under the general title Electrical installations of
buildings:
Part 1: Fundamental principles, assessment of general characteristics, definitions
Part 2: Void
Part 3: Void
Part 4: Protection for safety
Part 5: Selection and erection of electrical equipment
Part 6: Verification
Part 7: Requirements for special installations or locations
The committee has decided that the contents of this amendment and the base 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.

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60364-5-51  IEC:2005 – 9 –
ELECTRICAL INSTALLATIONS OF BUILDINGS –

Part 5-51: Selection and erection of electrical equipment –
Common rules


510 Introduction
510.1 Scope
This part of IEC 60364 deals with the selection of equipment and its erection. It provides
common rules for compliance with measures of protection for safety, requirements for proper
functioning for intended use of the installation, and requirements appropriate to the external
influences foreseen.
510.2 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 60068-2-11:1981, Environmental testing – Part 2: Tests. Test Ka: Salt mist
IEC 60073:1996, Basic and safety principles for man-machine interface, marking and
identification – Coding principles for indication devices and actuators
IEC 60079 (all parts), Electrical apparatus for explosive gas atmospheres
IEC 60255-22-1:1988, Electrical relays – Part 22: Electrical disturbance tests for measuring
relays and protection equipment – Section 1: 1 MHz burst disturbance tests
IEC 60364-1:2001, Electrical installations of buildings – Part 1: Fundamental principles
IEC 60364-4-41:2001, Electrical installations of buildings – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60364-4-42:2001, Electrical installations of buildings – Part 4-42: Protection for safety –
Protection against thermal effects
IEC 60364-4-44:2001, Electrical installations of buildings – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-5-52:2001, Electrical installations of buildings − Part 5-52: Selection and erection
of electrical equipment – Wiring systems
IEC 60364-5-54, Electrical installations of buildings − Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements and protective conductors and protective
bonding conductors
IEC 60446:1999, Basic and safety principles for man-machine interface, marking and
identification – Identification of conductors by colours or numerals
IEC 60447:1993, Man-machine interface (MMI) – Actuating principles

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60364-5-51  IEC:2005 – 11 –
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
1
IEC 60617-DB:2001 , Graphical symbols for diagrams
IEC 60707:1999, Flammability of solid non-metallic materials when exposed to flame sources –
List of test methods
IEC 60721-3-0:1984, Classification of environmental conditions – Part 3: Classification of
groups of environmental parameters and their severities – Introduction
IEC 60721-3-3:1994, Classification of environmental conditions – Part 3: Classification of
groups of environmental parameters and their severities – Section 3: Stationary use at
weather-protected locations
IEC 60721-3-4:1995, Classification of environmental conditions – Part 3: Classification of
groups of environmental parameters and their severities – Section 4: Stationary use at non-
weatherprotected locations
IEC 60884-1:2002, Plugs and socket-outlets for household and similar purposes – Part 1:
General requirements
IEC 61000-2 (all parts) Electromagnetic compatibility (EMC) – Part 2: Environment
IEC 61000-2-2:1990, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 2:
Compatibility levels for low-frequency conducted disturbances and signalling in public low-
voltage power supply systems
IEC 61000-2-5:1995, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 5:
Classification of electromagnetic environments. Basic EMC publication
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 2: Electrostatic discharge immunity test. Basic EMC publication
IEC 61000-4-3:2002, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement
techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test. Basic EMC publication
IEC 61000-4-6:1996, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 6: Immunity to conducted disturbances, induced by radio-frequency
fields
IEC 61000-4-8:1993, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 8: Power frequency magnetic field immunity test. Basic EMC publication
IEC 61000-4-12:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 12: Oscillatory waves immunity test. Basic EMC publication
IEC 61024-1:1990, Protection of structures against lightning – Part 1: General principles
IEC 61082 (all parts), Preparation of documents used in electrotechnology
___________
1
  “DB” refers to the IEC on-line database.

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60364-5-51  IEC:2005 – 13 –
IEC 61140:2001, Protection against electric shock – Common aspects for installation and
equipment
IEC 61346-1:1996, Industrial systems, installations and equipment and industrial products –
Structuring principles and reference designations – Part 1: Basic rules
510.3 General
Every item of equipment shall be selected and erected so as to allow compliance with the
rules stated in the following clauses of this part of IEC 60364 and the relevant rules in other
parts of the IEC 60364 series.
511 Compliance with standards
511.1 Every item of equipment shall comply with such standards as are appropriate and, in
addition, with any applicable standards of the ISO.
511.2 Where there are no applicable or ISO standards, the item of equipment concerned
shall be selected by special agreement between the person specifying the installation and the
installer.
512 Operational conditions and external influences
512.1 Operational conditions
512.1.1 Voltage
Equipment shall be suitable for the nominal voltage (r.m.s. value for a.c.) of the installation.
If, in IT installations, the neutral conductor is distributed, equipment connected between
phase and neutral shall be insulated for the voltage between phases.
NOTE For certain equipment, it may be necessary to take account of the highest and/or lowest voltage likely to
occur in normal service.
512.1.2 Current
Equipment shall be selected for the design current (r.m.s. value for a.c.) which it has to carry
in normal service.
Equipment shall also be capable of carrying the currents likely to flow in abnormal conditions
for such periods of time as are determined by the characteristics of the protective devices.
512.1.3 Frequency
If frequency has an influence on the characteristics of equipment, the rated frequency of the
equipment shall correspond to the frequency of the current in the circuit concerned.
512.1.4 Power
Equipment selected for its power characteristics shall be suitable for the normal operational
conditions taking account of the load factor.

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60364-5-51  IEC:2005 – 15 –
512.1.5 Compatibility
Unless other suitable precautions are taken during erection, all equipment shall be selected
so that it will not cause harmful effects on other equipment nor impair the supply during
normal service, including switching operations.
512.2 External influences
512.2.1 Electrical equipment shall be selected and erected in accordance with the
requirements of Table 51A, which indicates the characteristics of equipment necessary
according to the external influences to which the equipment may be subjected.
Equipment characteristics shall be determined either by a degree of protection or by
conformity to tests.
512.2.2 If the equipment does not, by its construction, have the characteristics relevant to
the external influences of its location, it may nevertheless be used on condition that it is
provided with appropriate additional protection in the erection of the installation. Such
protection shall not adversely affect the operation of the equipment thus protected.
512.2.3 When different external influences occur simultaneously, they may have
independent or mutual effect and the degree of protection shall be provided accordingly.
512.2.4 The selection of equipment according to external influences is necessary not only
for proper functioning, but also to ensure the reliability of the measures of protection for
safety complying with the rules of IEC 60364 generally. Measures of protection afforded by
the construction of equipment are valid only for the given conditions of external influence if
the corresponding equipment specification tests are made in these conditions of external
influence.
NOTE 1  For the purposes of this standard, the following classes of external influences are conventionally
regarded as normal:
AA Ambient temperature  AA4
AB Atmospheric humidity AB4
Other environmental conditions  XX1 of each parameter
(AC to AR)

Utilization and construction XX1 of each parameter, except

of buildings (B and C) XX2 for the parameter BC

NOTE 2  The word "normal" appearing in the third column of the table signifies that the equipment must generally
satisfy applicable IEC standards.

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60364-5-51  IEC:2005 – 17 –
Table 51A – Characteristics of external influences
Code External influences Characteristics required Reference
for selection and
erection of equipment
A Environmental conditions
AA Ambient temperature

The ambient temperature is that of the ambient
air where the equipment is to be installed
It is assumed that the ambient temperature
includes the effects of other equipment
installed in the same location
The ambient temperature to be considered for
the equipment is the temperature at the place
where the equipment is to be installed resulting
from the influence of all other equipment in the
same location, when operating, not taking into
account the thermal contribution of the
equipment to be installed
Lower and upper limits of ranges of ambient
temperature:

AA1 –60 °C +5 °C
Includes temperature range

of IEC 60721-3-3, class 3K8,


with high air temperature


restricted to +5 °C. Part of

temperature range of


 IEC 60721-3-4, class 4K4,


with low air temperature

  restricted to –60 °C and high

air temperature restricted
 
to +5 °C



Part of temperature range of

AA2 –40 °C +5 °C
IEC 60721-3-3, class 3K7,


with high air temperature


 restricted to +5 °C. Includes



part of temperature range
 
of IEC 60721-3-4, class 4K3,



Specially designed with high air temperature


equipment or appropriate restricted to +5 °C


a
arrangements

Part of temperature range
AA3 –25 °C +5 °C

of IEC 60721-3-3, class 3K6,

with high air temperature

 restricted to +5 °C. Includes

temperature range

of IEC 60721-3-4, class 4K1,

with high air temperature

restricted to +5 °C


AA4 –5 °C +40 °C Normal (in certain cases Part of the temperature range

special precautions may of IEC 60721-3-3, class 3K5,

be necessary) with the high air
temperatures restricted
to +40 °C

AA5 +5°C +40 °C Normal Identical to temperature
range of IEC 60721-3-3,
class 3K3
a
May necessitate certain supplementary precautions (e.g. special lubrication).
b
 This means that ordinary equipment will operate safely under the described external influences.
c
This means that special arrangements should be made, for example, between the designer of the installation
and the equipment manufacturer, e.g. for specially designed equipment.

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60364-5-51  IEC:2005 – 19 –
Table 51A (continued)
Code External influences Characteristics required for Reference
selection and erection of
equipment
AA6 +5 °C +60 °C Specially designed equipment Part of temperature range
a
of IEC 60721-3-3,
or appropriate arrangements
class 3K7, with low air
temperature restricted
to +5 °C and high air
temperature restricted
to +60 °C. Includes
temperature range
of IEC 60721-3-4, class
4K4 with low air tempera-
ture restricted to +5 °C

AA7 Specially designed equipment – Identical with temperature
–25 °C +55 °C
 a
range of IEC 60721-3-3,
or appropriate arrangements

class 3K6


AA8  – Identical with temperature
–50 °C +40 °C
range of IEC 60721-3-4,

class 4K3
Ambient temperature classes are applicable
only where humidity has no influence
The average temperature over a 24 h
period must not exceed 5 °C below the
upper limits
Combination of two ranges to define some
environments may be necessary.
Installations subject to temperatures
outside the ranges require special
consideration
AB Atmospheric humidity

Air Relative Absolute
temperature humidity humidity
3
°C %
g/m
a) low c) low
e) low
b) high d) high
f) high
AB1 –60 +5 3  100 0,003 7 Indoor and outdoor locations Includes temperature range
with extremely low ambient of IEC 60721-3-3,
temperatures class 3K8, with high air
temperature restricted

to +5 °C. Part of tempera-
Appropriate arrangements shall
ture range of IEC 60721-3-
c
be made 4, class 4K4, with low air
temperature restricted to –
60 °C and high air
temperature restricted
to +5 °C
AB2 –40 +5 10 100 0,1 7 Indoor and outdoor locations Part of temperature range
with low ambient temperatures of IEC 60721-3-3,
class 3K7, with high
Appropriate arrangements shall
temperature restricted
c
be made
to +5 °C. Part of
temperature range
of IEC 60721-3-4, class
4K4, with low air
temperature restricted to –
60 °C and high air
temperature restricted
to +5 °C
a
May necessitate certain supplementary precautions (e.g. special lubrication).
b
 This means that ordinary equipment will operate safely under the described external influences.
c
This means that special arrangements should be made, for example, between the designer of the installation and
the equipment manufacturer, e.g. for specially designed equipment.

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60364-5-51  IEC:2005 – 21 –
Table 51A (continued)
External influences
Air Relative Absolute Characteristics required
Code temperature humidity humidity for selection and erection Reference
3
°C % of equipment
g/m
Low high low high low high
AB3 -25 +5 10 100 0,5 7 Indoor and outdoor locations Part of temperature range
with low ambient of IEC 60721-3-3, class 3K6,
temperatures with high air temperature
restricted to +5 °C. Includes
Appropriate arrangements
temperature range
c
shall be made
of IEC 60721-3-4, class 4K1,
with high air temperature range
restricted to +5 °C

AB4 -5 +40 5 95 1 29
Weather protected locations Identical with temperature
having neither temperature range of IEC 60721-3-3,
nor humidity control. Heating class 3K5. The high air
may be used to raise low temperature restricted to
ambient temperatures +40 °C
b
Normal

AB5 +5 +40 5 85 1 25 Weather protected locations Identical with temperature
with temperature control range of IEC 60721-3-3,
class 3K3
b
Normal

AB6 +5 +60 10 100 1 35 Indoor and outdoor locations Part of temperature range
with extremely high ambient of IEC 60721-3-3, class 3K7,
temperatures, influence of with low air temperature
cold ambient temperatures restricted to +5 °C and high air
is prevented. Occurrence of temperature restricted
solar and heat radiation to +60 °C. Includes temperature
range of IEC 60721-3-4, class
Appropriate arrangements
4K4, with low air temperature
c
shall be made
restricted to +5 °C

AB7 -25 +55 10 100 0,5 29 Indoor weather-protected Identical with temperature
locations having neither range of IEC 60721-3-3,
temperature nor humidity class 3K6
control; the locations may
have openings directly to the
open air and be subjected to
solar radiation
Appropriate arrangements
c
shall be made

AB8 -50 +40 15 100 0,04 36 Outdoor and non-weather Identical with temperature
protected locations, with low range of IEC 60721-3-4, class
and high temperatures 4K3
Appropriate arrangements
c
shall be made
a
May necessitate certain supplementary precautions (e.g. special lubrication).
b
 This means that ordinary equipment will operate safely under the described external influences.
c
This means that special arrangements need to be made, for example, between the designer of the installation
and the equipment manufacturer, e.g. for specially designed equipment.
NOTE 1 All specified values are maximum or limit values which will have a low possibility of being exceeded.
NOTE 2 The low and high relative humidities are limited by the low and high absolute humidities, so that e.g. for
environmental parameters a and c, or b and d, the limit values given do not occur simultaneously. Therefore, Annex B
contains climatograms which describes the interdependence of air temperature, relative humidity and absolute humidity
for the climatic classes specified.

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60364-5-51  IEC:2005 – 23 –
Table 51A (continued)
Code External influences Characteristics required for selection Reference
and erection of equipment
AC Altitude
b
AC1
≤2 000 m Normal
May necessitate special precautions such as the
AC2 >2 000 m
application of derating factors
For some equipment special arrangements may be
necessary at altitudes of 1 000 m and above
AD Presence of water
AD1 Negligible Probability of presence of water is negligible IEC 60721-3-4, class 4Z6
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
IEC 60529
IPX0

AD2 Free-falling drops Possibility of vertically falling drops IEC 60721-3-3, class 3Z7
Location in which water vapour occasionally condenses
as drops or where steam may occasionally be present
IPX1 or IPX2 IEC 60529

AD3 Sprays Possibility of water falling as a spray at an angle up to IEC 60721-3-3, class 3Z8
60° from the vertical
IEC 60721-3-4, class 4Z7
Locations in which sprayed water forms a continuous

film on floors and/or walls

IPX3 IEC 60529

AD4 Splashes Possibility of splashes from any direction IEC 60721-3-3, class 3Z9
Locations where equipment may be subjected to IEC 60721-3-4, class 4Z7
splashed water; this applies, for example, to certain
external luminaires, construction site equipment
IPX4 IEC 60529

AD5 Jets Possibility of jets of water from any direction IEC 60721-3-3, class
3Z10
Locations where hot water is used regularly (yards,
car-washing bays) IEC 60721-3-4, class 4Z8
IPX5
IEC 60529
AD6 Waves Possibility of water waves IEC 60721-3-4, class 4Z9
Seashore locations such as piers, beaches, quays, etc.
IPX6 IEC 60529

AD7 Immersion Possibility of intermittent partial or total covering by
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
IEC 60529
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 IEC 60529
a
May necessitate certain supplementary precautions (e.g. special lubrication).
b
 This means that ordinary equipment will operate safely under the described external influences.
c
This means that special arrangements need to be made, for example, between the designer of the installation
and the equipment manufacturer, e.g. for specially designed equipment.

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60364-5-51  IEC:2005 – 25 –
Table 51A (continued)
Code External Characteristics required for selection and erection of Reference
influences equipment
AE Presence of foreign solid bodies or dust
AE1 Negligible The quantity or nature of dust or foreign solid bodies is not IEC 60721-3-3, class 3S1
significant IEC 60721-3-4, class 4S1
IP0X IEC 60529
AE2 Small objects Presence of foreign solid bodies where the smallest IEC 60721-3-3, class 3S2
(2,5 mm) dimension is not less than 2,5 mm IEC 60721-3-4, class 4S2
IP3X IEC 60529
Tools and small objects are examples of foreign solid
bodies of which the smallest dimension is at least 2,5 mm
AE3 Very small objects Presence of foreign solid bodies where the smallest IEC 60721-3-3, class 3S3
(1 mm) dimension is not less th
...