EN 62305-4:2006

SLOVENSKI STANDARD
01-junij-2006
1DGRPHãþD
SIST IEC 61312-1:1998
SIST IEC TR 61312-4:2000
SIST IEC TS 61312-2:2000
SIST-TS IEC/TS 61312-3:2004
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Protection against lightning -- Part 4: Electrical and electronic systems within structures
Blitzschutz -- Teil 4: Elektrische und elektronische Systeme in baulichen Anlagen
Protection contre la foudre -- Partie 4: Réseaux de puissance et de communication dans
les structures
Ta slovenski standard je istoveten z: EN 62305-4:2006
ICS:
91.120.40 =DãþLWDSUHGVWUHOR Lightning protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62305-4
NORME EUROPÉENNE
February 2006
EUROPÄISCHE NORM
ICS 29.020; 91.120.40
English version
Protection against lightning
Part 4: Electrical and electronic systems within structures
(IEC 62305-4:2006)
Protection contre la foudre Blitzschutz
Partie 4: Réseaux de puissance et de Teil 4: Elektrische und elektronische
communication dans les structures Systeme in baulichen Anlagen
(CEI 62305-4:2006) (IEC 62305-4:2006)

This European Standard was approved by CENELEC on 2006-02-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Rumania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62305-4:2006 E
Foreword
The text of document 81/265/FDIS, future edition 1 of IEC 62305-4, prepared by IEC TC 81, Lightning
protection, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 62305-4 on 2006-02-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2006-11-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-02-01
This European Standard makes reference to International Standards. Where the International Standard
referred to has been endorsed as a European Standard or a home-grown European Standard exists, this
European Standard shall be applied instead. Pertinent information can be found on the CENELEC web
site.
__________
Endorsement notice
The text of the International Standard IEC 62305-4:2006 was approved by CENELEC as a European
Standard without any modification.
__________
IEC 62305-4
Edition 1.0 2006-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 4: Electrical and electronic systems within structures

Protection contre la foudre –
Partie 4: Réseaux de puissance et de communication dans les structures

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XD
CODE PRIX
ICS 29.020; 91.120.40 ISBN 2-8318-8367-9

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CONTENTS
FOREWORD.5
INTRODUCTION.7

1 Scope.9
2 Normative references .9
3 Terms and definitions .10
4 Design and installation of a LEMP protection measures system (LPMS) .23
4.1 Design of an LPMS.16
4.2 Lightning protection zones (LPZ) .16
4.3 Basic protection measures in an LPMS .20
5 Earthing and bonding .20
5.1 Earth termination system.21
5.2 Bonding network.23
5.3 Bonding bars .28
5.4 Bonding at the boundary of an LPZ .28
5.5 Material and dimensions of bonding components.28
6 Magnetic shielding and line routing.29
6.1 Spatial shielding.29
6.2 Shielding of internal lines .29
6.3 Routing of internal lines.29
6.4 Shielding of external lines .30
6.5 Material and dimensions of magnetic shields.30
7 Coordinated SPD protection .30
8 Management of an LPMS .31
8.1 LPMS management plan .31
8.2 Inspection of an LPMS .33
8.3 Maintenance.34

Annex A (informative) Basics for evaluation of electromagnetic environment in a LPZ .35
Annex B (informative) Implementation of LEMP protection measures for electronic
systems in existing structures .61
Annex C (informative) SPD coordination .78
Annex D (informative) Selection and installation of a coordinated SPD protection.96

Bibliography.101

Figure 1 – General principle for the division into different LPZ .13
Figure 2 – Protection against LEMP – Examples of possible LEMP protection
measures systems (LPMS) .15
Figure 3 – Examples for interconnected LPZ.18
Figure 4 – Examples for extended lightning protection zones .19
Figure 5 – Example of a three-dimensional earthing system consisting of the bonding
network interconnected with the earth termination system.21
Figure 6 – Meshed earth termination system of a plant .22

62305-4 © IEC:2006 – 3 –
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Figure 7 – Utilization of reinforcing rods of a structure for equipotential bonding.24
Figure 8 – Equipotential bonding in a structure with steel reinforcement .25
Figure 9 – Integration of electronic systems into the bonding network.26
Figure 10 – Combinations of integration methods of electronic systems into the
bonding network .27
Figure A.1 – LEMP situation due to lightning flash .37
Figure A.2 – Simulation of the rise of magnetic field by damped oscillations .39
Figure A.3 – Large volume shield built by metal reinforcement and metal frames.40
Figure A.4 – Volume for electrical and electronic systems inside an inner LPZ n.41
Figure A.5 – Reducing induction effects by line routing and shielding measures .43
Figure A.6 – Example of an LPMS for an office building.44
Figure A.7 – Evaluation of the magnetic field values in case of a direct lightning flash .46
Figure A.8 – Evaluation of the magnetic field values in case of a nearby lightning flash .48
Figure A.9 – Distance s depending on rolling sphere radius and structure dimensions .51
a
Figure A.10 – Types of grid-like large volume shields .53
Figure A.11 – Magnetic field strength H inside a grid-like shield Type 1.54
1/max
Figure A.12 – Magnetic field strength H inside a grid-like shield Type 1.54
1/max
Figure A.13 – Low-level test to evaluate the magnetic field inside a shielded structure .56
Figure A.14 – Voltages and currents induced into a loop built by lines .57
Figure B.1 – Upgrading of LEMP protection measures and electromagnetic
compatibility in existing structures .63
Figure B.2 – Possibilities to establish LPZs in existing structures.69
Figure B.3 – Reduction of loop area using shielded cables close to a metal plate .71
Figure B.4 – Example of a metal plate for additional shielding .72
Figure B.5 – Protection of aerials and other external equipment .74
Figure B.6 – Inherent shielding provided by bonded ladders and pipes .75
Figure B.7 – Ideal positions for lines on a mast (cross-section of steel lattice mast).76
Figure C.1 – Example for the application of SPD in power distribution systems.79
Figure C.2 – Basic model for energy coordination of SPD .81
Figure C.3 – Combination of two voltage-limiting type SPDs .82
Figure C.4 – Example with two voltage-limiting type MOV 1 and MOV 2.84
Figure C.5 – Combination of voltage-switching type spark gap and voltage-limiting type
MOV .85
Figure C.6 – Example with voltage-switching type spark gap and voltage-limiting type MOV.86
Figure C.7 – Determination of decoupling inductance for 10/350 µs and 0,1kA/µs surges .87
Figure C.8 – Example with spark gap and MOV for a 10/350 µs surge .89

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Figure C.9 – Example with spark gap and MOV for 0,1kA/µs surge.91
Figure C.10 – Coordination variant I – Voltage-limiting type SPD .92
Figure C.11 – Coordination variant II – Voltage-limiting type SPD .93
Figure C.12 – Coordination variant III – Voltage-switching type SPD and voltage-
limiting type SPD .93
Figure C.13 – Coordination variant IV – Several SPDs in one element.94
Figure C.14 – Coordination according to the “let through energy” method .94
Figure D.1 – Surge voltage between live conductor and bonding bar .97

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROTECTION AGAINST LIGHTNING –

Part 4: Electrical and electronic systems within structures

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) 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 62305-4 has been prepared by IEC technical committee 81:
Lightning protection.
The IEC 62305 series (Parts 1 to 5), is produced in accordance with the New Publications
Plan, approved by National Committees (81/171/RQ (2001-06-29)), which restructures in a
more simple and rational form and updates the publications of the IEC 61024 series,
IEC 61312 series and the IEC 61663 series.
The text of this first edition of IEC 62305-4 is compiled from and replaces
– IEC 61312-1, first edition (1995);
– IEC 61312-2, first edition (1998);
– IEC 61312-3, first edition (2000);
– IEC 61312-4, first edition (1998).

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The text of this standard is based on the following documents:
FDIS Report on voting
81/265/FDIS 81/270/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, as close as possible, in accordance with the ISO/IEC
Directives, Part 2.
IEC 62305 consists of the following parts, under the general title Protection against lightning:
Part 1: General principles
Part 2: Risk management
Part 3: Physical damage to structures and life hazard
Part 4: Electrical and electronic systems within structures
Part 5: Services
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.
———————
To be published.
62305-4 © IEC:2006 – 7 –
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INTRODUCTION
Lightning as a source of harm is a very high-energy phenomenon. Lightning flashes release
many hundreds of mega-joules of energy. When compared with the milli-joules of energy that
may be sufficient to cause damage to sensitive electronic equipment in electrical and
electronic systems within a structure, it is clear that additional protection measures will be
necessary to protect some of this equipment.
The need for this International Standard has arisen due to the increasing cost of failures of
electrical and electronic systems, caused by electromagnetic effects of lightning. Of particular
importance are electronic systems used in data processing and storage as well as process
control and safety for plants of considerable capital cost, size and complexity (for which plant
outages are very undesirable for cost and safety reasons).
Lightning can cause different types of damage in a structure, as defined in IEC 62305-2:
D1 injuries to living beings due to touch and step voltages;
D2 physical damage due to mechanical, thermal, chemical and explosive effects;
D3 failures of electrical and electronic systems due to electromagnetic effects.
IEC 62305-3 deals with the protection measures to reduce the risk of physical damage and
life hazard, but does not cover the protection of electrical and electronic systems.
This Part 4 of IEC 62305 therefore provides information on protection measures to reduce the
risk of permanent failures of electrical and electronic systems within structures.
Permanent failure of electrical and electronic systems can be caused by the lightning
electromagnetic impulse (LEMP) via:
a) conducted and induced surges transmitted to apparatus via connecting wiring;
b) the effects of radiated electromagnetic fields directly into apparatus itself.
Surges to the structure can be generated externally or internally:
– surges external to the structure are created by lightning flashes striking incoming lines or
the nearby ground, and are transmitted to electrical and electronic systems via these lines;
– surges internal to the structure are created by lightning flashes striking the structure or the
nearby ground.
The coupling can arise from different mechanisms:
– resistive coupling (e.g. the earth impedance of the earth termination system or the cable
shield resistance);
– magnetic field coupling (e.g. caused by wiring loops in the electrical and electronic system
or by inductance of bonding conductors);
– electric field coupling (e.g. caused by rod antenna reception).
NOTE The effects of electric field coupling are generally very small when compared to the magnetic field coupling
and can be disregarded.
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Radiated electromagnetic fields can be generated via
– the direct lightning current flowing in the lightning channel,
– the partial lightning current flowing in conductors (e.g. in the down conductors of an
external LPS according to IEC 62305-3 or in an external spatial shield according to this
standard).
62305-4 © IEC:2006 – 9 –
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PROTECTION AGAINST LIGHTNING –

Part 4: Electrical and electronic systems within structures

1 Scope
This part of IEC 62305 provides information for the design, installation, inspection,
maintenance and testing of a LEMP protection measures system (LPMS) for electrical and
electronic systems within a structure, able to reduce the risk of permanent failures due to
lightning electromagnetic impulse.
This standard does not cover protection against electromagnetic interference due to lightning,
which may cause malfunctioning of electronic systems. However, the information reported in
Annex A can also be used to evaluate such disturbances. Protection measures against
electromagnetic interference are covered in IEC 60364-4-44 and in the IEC 61000 series [1] .
This standard provides guidelines for cooperation between the designer of the electrical and
electronic system, and the designer of the protection measures, in an attempt to achieve
optimum protection effectiveness.
This standard does not deal with detailed design of the electrical and electronic systems
themselves.
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 60364-4-44:2001, Electrical installations of buildings – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-5-53:2001, Electrical installations of building – Part 5-53: Selection and erection of
electrical equipment– Isolation, switching and control
IEC 60664-1:2002, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 61000-4-5:1995, Electromagnetic compatibility (EMC) – Part 4-5: Testing and measure-
ment techniques – Surge immunity test
IEC 61000-4-9:1993, Electromagnetic compatibility (EMC) – Part 4-9: Testing and measure-
ment techniques – Pulse magnetic field immunity test
IEC 61000-4-10:1993, Electromagnetic compatibility (EMC) – Part 4-10: Testing and measure-
ment techniques – Damped oscillatory magnetic field immunity test
———————
Figures in square brackets refer to the biblography.

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IEC 61000-5-2:1997, Electromagnetic compatibility (EMC) – Part 5: Installation and mitigation
guidelines – Section 2: Earthing and cabling
IEC 61643-1:1998, Surge protective devices connected to low-voltage power distribution
systems – Part 1: Performance requirements and testing methods
IEC 61643-12:2002, Low-voltage surge protective devices – Part 12: Surge protective devices
connected to low-voltage power distribution systems – Selection and application principles
IEC 61643-21:2000, Low voltage surge protective devices – Part 21: Surge protective devices
connected to telecommunications and signalling networks – Performance requirements and
testing methods
IEC 61643-22:2004, Low voltage surge protective devices – Part 22: Surge protective devices
connected to telecommunications and signalling networks – Part 22: Selection and application
principles
IEC 62305-1, Protection against lightning. Part 1: General principles

IEC 62305-2, Protection against lightning. Part 2: Risk management
IEC 62305-3, Protection against lightning. Part 3: Physical damage to structures and life
hazard
ITU-T Recommendation K.20:2003, Resistibility of telecommunication equipment installed in a
telecommunications centre to overvoltages and overcurrents
ITU-T Recommendation K.21:2003, Resistibility of telecommunication equipment installed in
customer premises to overvoltages and overcurrent
3 Terms and definitions
For the purposes of this document, the following terms and definitions, as well as those given
in other parts of IEC 62305, apply.
3.1
electrical system
system incorporating low voltage power supply components
3.2
electronic system
system incorporating sensitive electronic components such as communication equipment,
computer, control and instrumentation systems, radio systems, power electronic installations
3.3
internal systems
electrical and electronic systems within a structure
3.4
lightning electromagnetic impulse
LEMP
electromagnetic effects of lightning current
NOTE It includes conducted surges as well as radiated impulse electromagnetic field effects.

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3.5
surge
transient wave appearing as overvoltage and/or overcurrent caused by LEMP
NOTE Surges caused by LEMP can arise from (partial) lightning currents, from induction effects in installation
loops and as a remaining threat downstream of SPD.
3.6
rated impulse withstand voltage level
U
w
impulse withstand voltage assigned by the manufacturer to the equipment or to a part of it,
characterizing the specified withstand capability of its insulation against overvoltages
NOTE For the purposes of this standard, only withstand voltage between live conductors and earth is considered.
3.7
lightning protection level
LPL
number related to a set of lightning current parameters values relevant to the probability that
the associated maximum and minimum design values will not be exceeded in naturally
occurring lightning
NOTE Lightning protection level is used to design protection measures according to the relevant set of lightning
current parameters.
3.8
lightning protection zone
LPZ
zone where the lightning electromagnetic environment is defined
NOTE The zone boundaries of an LPZ are not necessarily physical boundaries (e.g. walls, floor and ceiling).
3.9
LEMP protection measures system
LPMS
complete system of protection measures for internal systems against LEMP
3.10
grid-like spatial shield
magnetic shield characterized by openings
NOTE For a building or a room, it is preferably built by interconnected natural metal components of the structure
(e.g. rods of reinforcement in concrete, metal frames and metal supports).
3.11
earth-termination system
part of an external LPS which is intended to conduct and disperse lightning current into the
earth
3.12
bonding network
interconnecting network of all conductive parts of the structure and of internal systems (live
conductors excluded) to the earth-termination system
3.13
earthing system
complete system combining the earth-termination system and the bonding network
3.14
surge protective device
SPD
device intended to limit transient overvoltages and divert surge currents. It contains at least
one non linear component
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3.15
SPD tested with I
imp
SPDs which withstand the partial lightning current with a typical waveform 10/350 µs require a
corresponding impulse test current I
imp
NOTE For power lines, a suitable test current I is defined in the Class I test procedure of IEC 61643-1.
imp
3.16
SPD tested with I
n
SPDs which withstand induced surge currents with a typical waveform 8/20 µs require a
corresponding impulse test current I
n
NOTE For power lines a suitable test current I is defined in the Class II test procedure of IEC 61643-1.
n
3.17
SPD tested with a combination wave
SPDs that withstand induced surge currents with a typical waveform 8/20 µs and require a
corresponding impulse test current I
sc
NOTE For power lines a suitable combination wave test is defined in the Class III test procedure of IEC 61643-1
defining the open circuit voltage U 1,2/50 µs and the short-circuit current I 8/20 µs of an 2 Ω combination wave
oc sc
generator.
3.18
voltage switching type SPD
SPD that has a high impedance when no surge is present, but can have a sudden change in
impedance to a low value in response to a voltage surge
NOTE 1 Common examples of components used as voltage switching devices include spark gaps, gas discharge
tubes (GDT), thyristors (silicon controlled rectifiers) and triacs. These SPD are sometimes called "crowbar type“.
NOTE 2 A voltage switching device has a discontinuous voltage/current characteristic.
3.19
voltage-limiting type SPD
SPD that has a high impedance when no surge is present, but will reduce it continuously with
increased surge current and voltage
NOTE 1 Common examples of components used as non-linear devices are varistors and suppressor diodes.
These SPDs are sometimes called "clamping type“.
NOTE 2 A voltage-limiting device has a continuous voltage/current characteristic.
3.20
combination type SPD
SPD that incorporates both voltage-switching and voltage-limiting type components and which
may exhibit voltage-switching, voltage-limiting or both voltage-switching and voltage-limiting
behaviour, depending upon the characteristics of the applied voltage
3.21
coordinated SPD protection
set of SPD properly selected, coordinated and installed to reduce failures of electrical and
electronic systems
62305-4 © IEC:2006 – 13 –
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4 Design and installation of a LEMP protection measures system (LPMS)
Electrical and electronic systems are subject to damage from the lightning electromagnetic
impulse (LEMP). Therefore LEMP protection measures need to be provided to avoid failure of
internal systems.
Protection against LEMP is based on the lightning protection zone (LPZ) concept: the volume
containing systems to be protected shall be divided into LPZ. These zones are theoretically
assigned volumes of space where the LEMP severity is compatible with the withstand level of
the internal systems enclosed (see Figure 1). Successive zones are characterized by
significant changes in the LEMP severity. The boundary of an LPZ is defined by the protection
measures employed (see Figure 2).

LPZ 0
Antenna
Mast or railing
Electrical
power line
Boundary
of LPZ 2
Boundary
LPZ 1
LPZ 2 of LPZ 1
Equipment
Water
Bonding
pipe Telecommunication
location
line
Bonding of incoming services directly or by suitable SPD
IEC  2187/05
NOTE This figure shows an example for dividing a structure into inner LPZs. All metal services entering the
structure are bonded via bonding bars at the boundary of LPZ 1. In addition, the conductive services entering LPZ
2 (e.g. computer room) are bonded via bonding bars at the boundary of LPZ 2.
Figure 1 – General principle for the division into different LPZ

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I , H
0 0
LPZ 0
LPS + Shield LPZ 1
H
LPZ 1
Shield LPZ 2
H
LPZ 2
H
SPD 1/2 SPD 0/1
(SB) (MB)
Apparatus
(victim)
U , I , I U , I
2 2 U1 1 0 0
Housing
Partial lightning
current
IEC  2188/05
Figure 2a – LPMS using spatial shields and “coordinated SPD protection”– Apparatus well protected
against conducted surges (U < 2 0 2 0 2 0
LPS + Shield LPZ 1
I , H
0 0
LPZ 0
H
LPZ 1
H
SPD 0/1
(MB)
Apparatus
(victim)
U , I
1 1 U , I
0 0
Housing
Partial lightning
current
IEC  2189/05
Figure 2b – LPMS using spatial shield of LPZ 1 and SPD protection at entry of LPZ 1 – Apparatus protected
against conducted surges (U 1 0 1 0 1 0
62305-4 © IEC:2006 – 15 –
62305-4  IEC:2006 – 29 –
I , H
LPZ 0
0 0
LPS (No shielding)
LPZ 1
H
H
2 SPD 0/1/2
(MB)
LPZ 2 H
Apparatus
(victim) U , I
2 2
U , I
0 0
Partial lightning
Shielded housing
current
or chassis etc.
IEC  2190/05
Figure 2c – LPMS using internal line shielding and SPD protection at entry of LPZ 1 – Apparatus protected
against conducted surges (U 2 0 2 0 2 0
I , H
0 0
LPS (No shielding)
LPZ 0
H
LPZ 1
H
SPD
SPD 1/2
SPD 0/1
(SA)
(SB)
(MB)
Apparatus
(victim)
U , I U , I U , I
2 2 1 1 0 0
Housing
Partial lightning
current
IEC  2191/05
Figure 2d – LPMS using “coordinated SPD protection” only – Apparatus protected against conducted
surges (U < 2 0 0 0
NOTE 1 SPDs can be located at the following points (see also D.1.2):
- at boundary of LPZ 1 (e.g. at main distribution board MB);
- at boundary of LPZ 2 (e.g. at secondary distribution board SB);
- at or close to apparatus (e.g. at socket outlet SA).
NOTE 2 For detailed installation rules see also IEC 60364-5-53.
NOTE 3 Shielded (     ) and non shielded (     ) boundary.
Figure 2 – Protection against LEMP – Examples of possible
LEMP protection measures systems (LPMS)

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Permanent failure of electrical and electronic systems due to LEMP can be caused by:
– conducted and induced surges transmitted to apparatus via connecting wiring;
– effects of radiated electromagnetic fields impinging directly onto apparatus itself.
NOTE 1 Failures due to electromagnetic fields impinging directly onto the equipment are negligible provided that
the equipment complies with radio frequency emission tests and immunity tests as defined in the relevant EMC
product standards.
NOTE 2 For equipment not complying with relevant EMC product standards, Annex A provides information on how
to achieve protection against electromagnetic fields directly impinging onto this equipment. The equipment’s
withstand level against radiated magnetic fields needs to be selected in accordance with IEC 61000-4-9 and
IEC 61000-4-10.
4.1 Design of an LPMS
An LPMS can be designed for protection of equipment against surges and electromagnetic
fields. Figure 2 provides examples:
• An LPMS employing spatial shields and coordinated SPD protection will protect against
radiated magnetic fields and against conducted surges (see Figure 2a). Cascaded spatial
shields and coordinated SPDs can reduce magnetic field and surges to a lower threat
level.
• An LPMS employing a spatial shield of LPZ 1 and an SPD at the entry of LPZ 1 can
protect apparatus against the radiated magnetic field and against conducted surges (see
Figure 2b).
NOTE 1 The protection would not be sufficient, if the magnetic field remains too high (due to low shielding
effectiveness of LPZ 1) or if the surge magnitude remains too high (due to a high voltage protection level of the
SPD and due to the induction effects onto wiring downstream of the SPD).
• An LPMS created using shielded lines, combined with shielded equipment enclosures, will
protect against radiated magnetic fields. The SPD at the entry of LPZ 1 will provide
protection against conducted surges (see Figure 2c). To achieve a lower threat surge
level, a special SPD may be required (e.g. additional coordinated stages inside) to reach a
sufficient low voltage protection level.
• An LPMS created using a system of coordinated SPD protection, is only suitable to protect
equipment which is insensitive to radiated magnetic fields, since the SPDs will only
provide protection against conducted surges (see Figure 2d). A lower threat surge level
can be achieved using coordinated SPDs.
NOTE 2 Solutions according to Figures 2a to 2c are recommended especially for equipment, which does not
comply with relevant EMC product standards.
NOTE 3 An LPS according to IEC 62305-3, which only employs equipotential bonding SPDs, provides no effective
protection against failure of sensitive electrical and electronic systems. The LPS can be improved by reducing the
mesh dimensions and selecting suitable SPDs, so as to make it an effective component of the LPMS.
4.2 Lightning protection zones (LPZ)
With respect to lightning threat, the following LPZ are defined (see IEC 62305-1):
Outer zones
LPZ 0 Zone where the threat is due to the unattenuated lightning electromagnetic field
and where the internal systems may be subjected to full or partial lightning surge
current. LPZ 0 is subdivided into:
LPZ 0 zone where the threat is due to the direct lightning flash and the full lightning
A
electromagnetic field. The internal systems may be subjected to full lightning
surge current;
LPZ 0 zone protected against direct lightning flashes but where the threat is the full
B
lightning electromagnetic field. The internal systems may be subjected to partial
lightning surge currents.
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Inner zones: (protected against direct lightning flashes)
LPZ 1 Zone where the surge current is limited by current sharing and by SPDs at the
boundary. Spatial shielding may attenuate the lightning electromagnetic field.
LPZ 2 . n Zone where the surge current may be further limited by current sharing and by
additional SPDs at the boundary. Additional spatial shielding may be used to
further attenuate the lightning electromagnetic field.
The LPZs are implemented by the installation of the LPMS, e.g. installation of coordinated
SPDs and/or magnetic shielding (see Figure 2). Depending on number, type and withstand
level of the equipment to be protected, suitable LPZ can be defined. These may include small
local zones (e.g. equipment enclosures) or large integral zones (e.g. the volume of the whole
structure) (see Figure B.2).
Interconnection of LPZ of the same order may be necessary if either two separate structures
are connected by electrical or signal lines, or the number of required SPDs is to be reduced
(see Figure 3).
LPZ 0
LPZ 1 LPZ 1
i
2 SPD 0/1
SPD 0/1
a
i
i
IEC  2192/05
LPZ 0
LPZ 1 LPZ 1
i
b
i i
1 2
IEC  2193/05
i , i partial lightning currents
1 2
NOTE Figure 3a shows two LPZ 1 connected by NOTE Figure 3b shows, that this problem can be
electrical or signal lines. Special care should be taken if solved using shielded cables or shielded cable ducts to
both LPZ 1 represent separate structures with separate interconnect both LPZ 1, provided that the shields are
earthing systems, spaced tens or hundreds of metres able to carry the partial lightning current. The SPD can
from each other. In this case, a large part of the be omitted, if the voltage drop along the shield is not
lightning current can flow along the connecting lines, too high.
which are not protected.
Figure 3a – Interconnecting two LPZ 1 using SPD Figure 3b – Interconnecting two LPZ 1 using
shielded cables or shielded cable ducts

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62305-4  IEC:2006 – 35 –
LPZ 1
LPZ 2 LPZ 2
SPD 1/2 SPD 1/2
c
IEC  2194/05
LPZ 1
LPZ 2 LPZ 2
d
IEC  2195/05
NOTE Figure 3c shows two LPZ 2 connected by NOTE Figure 3d shows that such interference can be
electrical or signal lines. Because the lines are exposed avoided and the SPD can be omitted, if shielded cables
to the threat level of LPZ 1, SPD at the entry into each or shielded cable ducts are used to interconnect both
LPZ 2 are required. LPZ 2.
Figure 3c – Interconnecting two LPZ 2 using SPD Figure 3d – Interconnecting two LPZ 2 using
shielded cables or shielded cable ducts
Figure 3 – Examples for interconnected LPZ
Extending an LPZ into another LPZ might be needed in special cases or can be used to
reduce the number of required SPD (see Figure 4).
Detailed evaluation of the electromagnetic environment in an LPZ is described in Annex A.

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LPZ 0 LPZ 0
LPZ 1 LPZ 1
LPZ 0
SPD 0/1
SPD 0/1
IEC  2196/05 IEC  2197/05
a
b
NOTE Figure 4a shows a structure powered by a NOTE Figure 4b shows that the problem can be solved
transformer. If the transformer is placed outside the extending LPZ 0 into LPZ 1, which requires again SPDs
structure, only the low voltage lines entering the at the low voltage side only.
structure need protection by SPD. If the transformer
should be placed inside the structure, the owner of the
building often is not allowed to adopt protection
measures on the high voltage side.
Figure 4a – Transformer outside the structure Figure 4b – Transformer inside the structure (LPZ 0
extended into LPZ 1
LPZ 1 LPZ 1
LPZ 2 LPZ 2
SPD 1/2 SPD 0/1
SPD 0/1/2
IEC  2198/05 IEC  2199/05
c d
NOTE Figure 4c shows an LPZ 2 supplied by an NOTE Figure 4d shows that the line can enter
electrical or signal line. This line needs two coordinated immediately into LPZ 2 and only one SPD is required, if
SPDs: one at the boundary of LPZ 1, the other at the LPZ 2 is extended into LPZ 1 using shielded cables or
boundary of LPZ 2. shielded cable ducts. However this SPD will reduce the
threat immediately to the level of LPZ 2.

Figure 4c – Two coordinated SPD (0/1) and SPD (1/2) Figure 4d – Only one SPD (0/1/2) needed (LPZ 2
needed extended into LPZ 1)
Figure 4 – Examples for extended lightning protection zones

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4.3 Basic protection measures in an LPMS
Basic protection measures against LEMP include:
• Earthing and bonding (see Clause 5)
The earthing system conducts and disperses the lightning current into the earth.
The bonding network minimizes potential differences and may reduce magnetic field.
• Magnetic shielding and line routing (see Clause 6)
Spatial shielding attenuates the magnetic field inside the LPZ, arising from lightning
flashes direct to or nearby the structure, and reduces internal surges.
Shielding of internal lines, using shielded cables or cable ducts, minimizes internal
induced surges.
Routing of internal lines can minimize induction loops and reduce internal surges.
NOTE 1 Spatial shielding, shielding and routing of internal lines can be combined or used separately.
Shielding o
...