IEC 60364-4-44:2007
(Main)Low-voltage electrical installations - Part 4-44: Protection for safety - Protection against voltage disturbances and electromagnetic disturbances
Low-voltage electrical installations - Part 4-44: Protection for safety - Protection against voltage disturbances and electromagnetic disturbances
The rules of this Part of IEC 60364 are intended to provide requirements for the safety of electrical installations in the event of voltage disturbances and electromagnetic disturbances generated for different specified reasons. This second edition of IEC 60364-4-44 cancels and replaces the first edition published in 2001, amendment 1 (2003) and amendment 2 (2006). The contents of the corrigenda of May 2010 and October 2011 have been included in this copy.
Installations électriques à basse tension - Partie 4-44: Protection pour assurer la sécurité - Protection contre les perturbations de tension et les perturbations électromagnétiques
Les règles de la présente Partie de la CEI 60364 sont destinées à donner des exigences pour la sécurité des installations électriques en cas de perturbations de tension ou d'influences électromagnétiques dues à des raisons diverses. Cette deuxième édition de la CEI 60364-4-44 annule et remplace la première édition parue en 2001, l'amendement 1 (2003) et l'amendement 2 (2006). Le contenu des corrigendum de mai 2010 et octobre 2011 a été pris en considération dans cet exemplaire.
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Standards Content (Sample)
IEC 60364-4-44
Edition 2.0 2007-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage electrical installations –
Part 4-44: Protection for safety – Protection against voltage disturbances and
electromagnetic disturbances
Installations électriques à basse tension –
Partie 4-44: Protection pour assurer la sécurité – Protection contre les
perturbations de tension et les perturbations électromagnétiques
IEC 60364-4-44:2007
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IEC 60364-4-44
Edition 2.0 2007-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage electrical installations –
Part 4-44: Protection for safety – Protection against voltage disturbances and
electromagnetic disturbances
Installations électriques à basse tension –
Partie 4-44: Protection pour assurer la sécurité – Protection contre les
perturbations de tension et les perturbations électromagnétiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XA
CODE PRIX
ICS 91.140.50 ISBN 2-8318-9261-9
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– 2 – 60364-4-44 © IEC:2007
CONTENTS
FOREWORD.5
INTRODUCTION.7
440.1 Scope .8
440.2 Normative references.8
441 (Vacant).9
442 Protection of low-voltage installations against temporary overvoltages due to earth
faults in the high-voltage system and due to faults in the low-voltage system .9
442.1 Scope and object .9
442.1.1 General.9
442.1.2 Symbols .10
442.2 Overvoltages in LV-systems during a high-voltage earth fault .11
442.2.1 Magnitude and duration of power frequency fault-voltage .12
442.2.2 Magnitude and duration of power frequency stress-voltages.13
442.2.3 Requirements for calculation of limits .14
442.3 Power frequency stress voltage in case of loss of the neutral conductor in a
TN and TT system .14
442.4 Power frequency stress voltage in the event of an earth fault in an IT system
with distributed neutral .14
442.5 Power frequency stress voltage in the event of short-circuit between a line
conductor and the neutral conductor .14
443 Protection against overvoltages of atmospheric origin or due to switching.14
443.1 General .14
443.2 Classification of impulse withstand voltages (overvoltage categories) .15
443.2.1 Purpose of classification of impulse withstand voltages
(overvoltage categories) .15
443.2.2 Relationship between impulse withstand voltages of equipment and
overvoltage categories .15
443.3 Arrangements for overvoltage control.16
443.3.1 Inherent overvoltage control .16
443.3.2 Protective overvoltage control.16
443.4 Required impulse withstand voltage of equipment.18
444 Measures against electromagnetic influences.18
444.1 General .18
444.2 (void) .19
444.3 Definitions .19
444.4 Mitigation of Electromagnetic Interference (EMI) .20
444.4.1 Sources of EMI.20
444.4.2 Measures to reduce EMI.21
444.4.3 TN-system .22
444.4.4 TT system .26
444.4.5 IT system .27
444.4.6 Multiple-source supply.28
444.4.7 Transfer of supply .31
444.4.8 Services entering a building.33
444.4.9 Separate buildings.34
444.4.10 Inside buildings .34
444.4.11 Protective devices .36
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60364-4-44 © IEC:2007 – 3 –
444.4.12 Signal cables.36
444.5 Earthing and equipotential bonding.36
444.5.1 Interconnection of earth electrodes.36
444.5.2 Interconnection of incoming networks and earthing arrangements.37
444.5.3 Different structures for the network of equipotential conductors and
earthing conductors.37
444.5.4 Equipotential bonding networks in buildings with several floors .39
444.5.5 Functional earthing conductor.40
444.5.6 Commercial or industrial buildings containing significant amounts
of information technology equipment.41
444.5.7 Earthing arrangements and equipotential bonding of information
technology installations for functional purposes .41
444.6 Segregation of circuits .42
444.6.1 General.42
444.6.2 Design guidelines .42
444.6.3 Installation guidelines .43
444.7 Cable management systems .44
444.7.1 General.44
444.7.2 Design guidelines .44
444.7.3 Installation guidelines .45
445 Protection against undervoltage .47
445.1 General requirements .47
Annex A (informative) Explanatory notes concerning 442.1 and 442.2.48
Annex B (informative) Guidance for overvoltage control by SPDs applied to overhead
lines.50
Annex C (normative) Determination of the conventional length, d .52
Bibliography .54
Figure 44.A1 – Representative schematic sketch for possible connections to earth in
substation and LV-Installation and occurring overvoltages in case of faults .11
Figure 44.A2 – Tolerable fault-voltage due to an earth-fault in the HV system .13
Figure 44.R1 − By-pass conductor for screen reinforcement to provide a common
equipotential bonding system .21
Figure 44.R2 − Example of a substitute or by-pass equipotential bonding conductor in a
TT-system.22
Figure 44.R3A − Avoidance of neutral conductor currents in a bonded structure by
using the TN-S system from the origin of the public supply up to and including the final
circuit within a building .23
Figure 44.R3B − Avoidance of neutral conductor currents in a bonded structure by using
a TN-S system downstream of a consumer’s private supply transformer .24
Figure 44.R4 − TN-C-S system within an existing building installation .25
Figure 44.R5 – TT system within a building installation .26
Figure 44.R6 – IT system within a building installation .27
Figure 44.R7A – TN multiple-source power supply with a non-suitable multiple
connection between PEN and earth .28
Figure 44.R7B – TN multiple source power supplies to an installation with connection to
earth of the star points at one and the same point .29
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Figure 44.R8 – TT multiple-source power supplies to an installation with connection to
earth of the star points at one and the same point .30
Figure 44.R9A − Three-phase alternative power supply with a 4-pole switch .31
Figure 44.R9B – Neutral current flow in a three-phase alternative power supply with an
unsuitable 3-pole switch .32
Figure 44.R9C − Single-phase alternative power supply with 2-pole switch.33
Figure 44.R10 − Armoured cables and metal pipes entering the buildings (examples) .34
Figure 44.R11 − Illustration of measures in an existing building .35
Figure 44.R12 – Interconnected earth electrodes.36
Figure 44.R13 – Examples of protective conductors in star network .37
Figure 44.R14 – Example of multiple meshed bonding star network .38
Figure 44.R15 – Example of a common meshed bonding star network .39
Figure 44.R16 – Example of equipotential bonding networks in structures without
lightning protection systems .40
Figure 44.R17A − Separation between power and information technology cables for
cable route lengths ≤ 35 m .43
Figure 44.R17B − Separation between power and information technology cables for
cable route lengths > 35 m .43
Figure 44.R18 – Separation of cables in wiring systems.44
Figure 44.R19 – Cable arrangements in metal cable-trays .45
Figure 44.R20 – Continuity of metallic system components .46
Figure 44.R21 – Location of cables inside metallic construction elements .46
Figure 44.R22 – Connection of metallic sections.47
Figure 44.Q – Examples of how to apply d , d and d for the determination of d .53
1 2 3
Table 44.A1 – Power frequency stress voltages and power frequency fault voltage in the
low voltage system .12
Table 44.A2 – Permissible power frequency stress-voltage.13
Table 44.B – Required rated impulse withstand voltage of equipment .18
Table B.1 – Different possibilities for IT systems.51
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60364-4-44 © IEC:2007 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_______________
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –
Part 4-44: Protection for safety –
Protection against voltage disturbances and
electromagnetic disturbances
FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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 60364-4-44 has been prepared by IEC technical committee 64:
Electrical installations and protection against electric shock.
This second edition of IEC 60364-4-44 cancels and replaces the first edition published in 2001,
amendment 1 (2003) and amendment 2 (2006).
The document 64/1600/FDIS, circulated to the National Committees as Amendment 3, led to
the publication of the new edition.
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– 6 – 60364-4-44 © IEC:2007
The text of this standard is based on the first edition, its Amendment 1, Amendment 2 and the
following documents:
FDIS Report on voting
64/1600/FDIS 64/1609/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.
A list of all the parts in the IEC 60364 series, under the general title Low-voltage electrical
installations, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of
existing standards in this series will be updated at the time of the next edition.
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.
The contents of the corrigenda of May 2010 and October 2011 have been included in this
copy.
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60364-4-44 © IEC:2007 – 7 –
INTRODUCTION
Part 4-44 of IEC 60364 covers the protection of electrical installations and measures against
voltage disturbances and electromagnetic disturbances.
The requirements are arranged into four clauses as follows:
Clause 442 Protection of low-voltage installations against temporary overvoltages due to
earth faults in the high-voltage system and due to faults in the low-voltage
system
Clause 443 Protection against overvoltages of atmospheric origin or due to switching
Clause 444 Measures against electromagnetic influences
Clause 445 Protection against undervoltage
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LOW-VOLTAGE ELECTRICAL INSTALLATIONS –
Part 4-44: Protection for safety –
Protection against voltage disturbances and
electromagnetic disturbances
440.1 Scope
The rules of this Part of IEC 60364 are intended to provide requirements for the safety of
electrical installations in the event of voltage disturbances and electromagnetic disturbances
generated for different specified reasons.
The rules of this part are not intended to apply to systems for distribution of energy to the
public, or power generation and transmission for such systems (see the scope of IEC 60364-1)
although such disturbances may be conducted into or between electrical installations via these
supply systems.
440.2 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 60038:1983, IEC standard voltages
IEC 60050-604:1987, International Electrotechnical Vocabulary – Chapter 604: Generation,
transmission and distribution of electricity – Operation
IEC 60364-1, Low-voltage electrical installations – Part 1: Fundamental principles, assessment
of general characteristics, definitions
IEC 60364-4-41:2005, Electrical installations of buildings – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60364-5-54:2002, Electrical installations of buildings − Part 5-54: Selection and erection of
1
electrical equipment – Earthing arrangements and protective bonding conductors
IEC 60479-1:2005, Effects of current on human beings and livestock – Part 1: General aspects
IEC 60664-1:2007, Insulation co-ordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60950-1, Information technology equipment – Safety – Part 1: General requirements
IEC 61000-2-5:1995, Electromagnetic compatibility (EMC) − Part 2: Environment − Section 5:
Classification of electromagnetic environments – Basic EMC publication
IEC 61000-6-1, Electromagnetic compatibility (EMC) – Part 6-1: Generic standards – Immunity
for residential, commercial and light-industrial environments
IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards – Immunity
for industrial environments
___________
1
A third edition is currently in preparation.
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60364-4-44 © IEC:2007 – 9 –
IEC 61000-6-3, Electromagnetic compatibility (EMC) – Part 6-3: Generic standards – Emission
standard for residential, commercial and light-industrial environments
IEC 61000-6-4, Electromagnetic compatibility (EMC) – Part 6-4: Generic standards – Emission
standard for industrial environments
IEC 61558-2-1, Safety of power transformers, power supplies, reactors and similar products –
Part 2-1: Particular requirements for tests for separating transformers and power supplies
incorporating separating transformers for general applications
IEC 61558-2-4, Safety of power transformers, power supply units and similar – Part 2-4:
Particular requirements for isolating transformers for general use
IEC 61558-2-6, Safety of power transformers, power supply units and similar – Part 2-6:
Particular requirements for safety isolating transformers for general use
IEC 61558-2-15, Safety of power transformers, power supply units and similar – Part 2-15:
Particular requirements for isolating transformers for the supply of medical locations
IEC 61643 (all parts), Low-voltage surge protective devices
IEC 61936-1, Power installations exceeding 1 kV a.c. – Part 1: Common rules
IEC 62305-1, Protection against lightning – Part 1: General principles
IEC 62305-3, Protection against lightning – Part 3: Physical damage to structures and life
hazard
IEC 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within
structures
441 (Vacant)
442 Protection of low-voltage installations against temporary overvoltages due
to earth faults in the high-voltage system and due to faults in the low-
voltage system
442.1 Field of application
The rules of this clause provide requirements for the safety of low-voltage installation in the
event of
– a fault between the high-voltage system and earth in the transformer substation that
supplies the low-voltage installation,
– a loss of the supply neutral in the low-voltage system,
– a short-circuit between a line conductor and neutral,
– an accidental earthing of a line conductor of a low-voltage IT-system.
The requirements for the earthing arrangement at the transformer substation are given in
IEC 61936-1.
442.1.1 General requirements
As Clause 442 covers faults between a high-voltage line and the earth in the HV/LV substation,
it gives rules for the designer and installer of the substation. It is necessary to have the
following information concerning the high-voltage system:
– quality of the system earthing;
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