EN 62305-1:2006

SLOVENSKI SIST EN 62305-1:2006

STANDARD
junij 2006
Zaščita pred delovanjem strele – 1. del: Splošna načela
Protection against lightning - Part 1: General principles
ICS 91.120.40 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

Corrigendum to EN 62305-1:2006
English version
___________
Foreword
the last paragraph by:
Replace
Annex ZA has been added by CENELEC.

Annex ZA (see overleaf):
Add
November 2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

1) 2)
IEC 62305-2 - Protection against lightning EN 62305-2 2006
Part 2: Risk management
1) 2)
IEC 62305-3 (mod) - Protection against lightning EN 62305-3 2006
Part 3: Physical damage to structures and life
hazard
1) 2)
IEC 62305-4 - Protection against lightning EN 62305-4 2006
Part 4: Electrical and electronic systems
within structures
3)
IEC 62305-5 - Protection against lightning - -
Part 5: Services
___________
1)
Undated reference.
2)
Valid edition at date of issue.
3)
To be published.
IEC 62305-1
Edition 1.0 2006-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 1: General principles
Protection contre la foudre –
Partie 1: Principes généraux
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XB
CODE PRIX
ICS 29.020; 91.120.40 ISBN 2-8318-8358-X

62305-1  IEC:2006 – 3 – – 2 – 62305-1 © IEC:2006
CONTENTS
FOREWORD.5
INTRODUCTION.7

1 Scope.8
2 Normative references.8
3 Terms and definitions .8
4 Lightning current parameters .14
5 Damage due to lightning .14
5.1 Damage to a structure .14
5.2 Damage to a service.17
5.3 Types of loss .18
6 Need and economic convenience for lightning protection.20
6.1 Need for lightning protection .20
6.2 Economic convenience of lightning protection .21
7 Protection measures .21
7.1 Protection measures to reduce injury of living beings due to touch and step
voltages.21
7.2 Protection measures to reduce physical damage.21
7.3 Protection measures to reduce failure of electrical and electronic systems .22
7.4 Protection measures selection .22
8 Basic criteria for protection of structures and services.22
8.1 Lightning protection levels (LPL) .23
8.2 Lightning protection zones (LPZ).27
8.3 Protection of structures.28
8.4 Protection of services .29

Annex A (informative) Parameters of lightning current .30
Annex B (informative) Time functions of the lightning current for analysis purposes .38
Annex C (informative) Simulation of the lightning current for test purposes .44
Annex D (informative) Test parameters simulating the effects of lightning on LPS
components .48
Annex E (informative) Surges due to lightning at different installation points .63

Bibliography .68

62305-1 © IEC:200662305-1  IEC:2006 – 5 – – 3 –

Figure 1 – Types of loss and corresponding risks resulting from different types of
damage.20
Figure 2 – LPZ defined by an LPS (IEC 62305-3).25
Figure 3 – LPZ defined by protection measures against LEMP (IEC 62305-4) .26
Figure A.1 – Definitions of short stroke parameters (typically T <2 ms).30
Figure A.2 – Definitions of long stroke parameters (typically 2 ms long
Figure A.3 – Possible components of downward flashes (typical in flat territory and to
lower structures) .31
Figure A.4 – Possible components of upward flashes (typical to exposed and/or higher
structures) .32
Figure A.5 – Cumulative frequency distribution of lightning current parameters (lines
through 95 % and 5 % value).35
Figure B.1 – Waveshape of the current rise of the first short stroke .39
Figure B.2 – Waveshape of the current tail of the first short stroke .40
Figure B.3 – Waveshape of the current rise of the subsequent short strokes.41
Figure B.4 – Waveshape of the current tail of the subsequent short strokes.42
Figure B.5 – Amplitude density of the lightning current according to LPL I .43
Figure C.1 – Example test generator for the simulation of the specific energy of the first
short stroke and the charge of the long stroke .45
Figure C.2 – Definition for the current steepness in accordance with Table C.3.46
Figure C.3 – Example test generator for the simulation of the front steepness of the
first short stroke for large test items .47
Figure C.4 – Example test generator for the simulation of the front steepness of the
subsequent short strokes for large test items.47
Figure D.1 – General arrangement of two conductors for the calculation of
electrodynamic force .55
Figure D.2 – Typical conductor arrangement in an LPS.55
Figure D.3 – Diagram of the stresses for the configuration of Figure D.2.56
Figure D.4 – Force per unit length along the horizontal conductor of Figure D.2 .56

Table 1 – Effects of lightning on typical structures .15
Table 2 – Effects of lightning on typical services.17
Table 3 – Damages and loss in a structure according to different points of strike of
lightning .19
Table 4 – Damages and loss in a service according to different points of strike of
lightning .19
Table 5 – Maximum values of lightning parameters according to LPL.24
Table 6 – Minimum values of lightning parameters and related rolling sphere radius
corresponding to LPL .27
Table 7 – Probabilities for the limits of the lightning current parameters .27
Table A.1 – Tabulated values of lightning current parameters taken from CIGRE
[3], [4]
(Electra No. 41 or No. 69*) .33
Table A.2 – Logarithmic normal distribution of lightning current parameters –
µ
Mean and dispersion σ calculated from 95 % and 5 % values from CIGRE (Electra
log
[3], [4]
No. 41 or No. 69) .34

62305-1  IEC:2006 – 7 – – 4 – 62305-1 © IEC:2006
Table B.1 – Parameters for Equation B.1.38
Table C.1 – Test parameters of the first short stroke .45
Table C.2 – Test parameters of the long stroke .45
Table C.3 – Test parameters of the short strokes .46
Table D.1 – Summary of the lightning threat parameters to be considered in the
calculation of the test values for the different LPS components and for the different LPL.49
Table D.2 – Physical characteristics of typical materials used in LPS components .52
Table D.3 – Temperature rise for conductors of different sections as a function of W/R .52
Table E.1 – Conventional earthing impedance values Z and Z according to the
resistivity of the soil.64
Table E.2 – Expected surge overcurrents due to lightning flashes .65

62305-1 © IEC:200662305-1  IEC:2006 – 9 – – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROTECTION AGAINST LIGHTNING –

Part 1: General principles
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 62305-1 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 and updates
in a more simple and rational form the publications of the IEC 61024 series, the IEC 61312
series and the IEC 61663 series.
The text of this first edition of IEC 62305-1 is compiled from and replaces
– IEC 61024-1-1, first edition (1993).

62305-1  IEC:2006 – 11 – – 6 – 62305-1 © IEC:2006
The text of this standard is based on the following documents:
FDIS Report on voting
81/262/FDIS 81/267/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
62305-1 © IEC:200662305-1  IEC:2006 – 13 – – 7 –
INTRODUCTION
There are no devices nor methods capable of modifying the natural weather phenomena to the
extent that they can prevent lightning discharges. Lightning flashes to, or nearby, structures (or
services connected to the structures) are hazardous to people, to the structures themselves,
their contents and installations as well as to services. This is why the application of lightning
protection measures is essential.
The need for protection, the economic benefits of installing protection measures and the
selection of adequate protection measures should be determined in terms of risk management.
Risk management is the subject of IEC 62305-2.
The criteria for design, installation and maintenance of lightning protection measures are
considered in three separate groups:
– the first group concerns protection measures to reduce physical damage and life hazard in
a structure is given in IEC 62305-3,
– the second group concerns protection measures to reduce failures of electrical and
electronic systems in a structure is given in IEC 62305-4,
– the third group concerns protection measures to reduce physical damage and failures of
services connected to a structure (mainly electrical and telecommunication lines) is given in
IEC 62305-5.
62305-1  IEC:2006 – 15 – – 8 – 62305-1 © IEC:2006
PROTECTION AGAINST LIGHTNING –

Part 1: General principles
1 Scope
This part of IEC 62305 provides the general principles to be followed in the protection against
lightning of
– structures including their installations and contents as well as persons,
– services connected to a structure.
The following cases are outside the scope of this standard:
– railway systems;
– vehicles, ships, aircraft, offshore installations;
– underground high pressure pipelines;
− pipe, power and telecommunication lines not connected to a structure.
NOTE Usually these systems are under special regulations made by various specific authorities.
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 62305-2, Protection against lightning – Part 2: Risk management
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
IEC 62305-5, Protection against lightning – Part 5: Services
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
lightning flash to earth
electrical discharge of atmospheric origin between cloud and earth consisting of one or more
strokes
___________
To be published.
62305-1 © IEC:200662305-1  IEC:2006 – 17 – – 9 –
3.2
downward flash
lightning flash initiated by a downward leader from cloud to earth
NOTE A downward flash consists of a first short stroke, which can be followed by subsequent short strokes. One
or more short strokes may be followed by a long stroke.
3.3
upward flash
lightning flash initiated by an upward leader from an earthed structure to cloud
NOTE An upward flash consists of a first long stroke with or without multiple superimposed short strokes. One or
more short strokes may be followed by a long stroke.
3.4
lightning stroke
single electrical discharge in a lightning flash to earth
3.5
short stroke
part of the lightning flash which corresponds to an impulse current
NOTE This current has a time to the half value T typically less than 2 ms (see Figure A.1).
3.6
long stroke
part of the lightning flash which corresponds to a continuing current
NOTE The duration time T (time from the 10 % value on the front to the 10 % value on the tail) of this
long
continuing current is typically more than 2 ms and less than 1 s (see Figure A.2)
3.7
multiple strokes
lightning flash consisting on average of 3-4 strokes, with typical time interval between them of
about 50 ms
NOTE Events having up to a few dozen strokes with intervals between them ranging from 10 ms to 250 ms have
been reported.
3.8
point of strike
point where a lightning flash strikes the earth, or protruding object (e.g. structure, LPS, service,
tree, etc.)
NOTE A lightning flash may have more than one point of strike.
3.9
lightning current
i
current flowing at the point of strike
3.10
peak value
I
maximum value of the lightning current
3.11
average steepness of the front of short stroke current
average rate of change of current within a time interval t – t
2 1
NOTE It is expressed by the difference i(t ) – i(t ) of the values of the current at the start and at the end of this
2 1
interval, divided by t – t (see Figure A.1).
2 1
62305-1  IEC:2006 – 19 – – 10 – 62305-1 © IEC:2006
3.12
front time of short stroke current
T
virtual parameter defined as 1,25 times the time interval between the instants when the 10 %
and 90 % of the peak value are reached (see Figure A.1)
3.13
virtual origin of short stroke current
O
point of intersection with time axis of a straight line drawn through the 10 % and the 90 %
reference points on the stroke current front (see Figure A.1); it precedes by 0,1 T that instant
at which the current attains 10 % of its peak value
3.14
time to half value of short stroke current
T
virtual parameter defined as the time interval between the virtual origin O and the instant at
which the current has decreased to half the peak value (see Figure A.1)
3.15
flash duration
T
time for which the lightning current flows at the point of strike
3.16
duration of long stroke current
T
long
time duration during which the current in a long stroke is between the 10 % of the peak value
during the increase of the continuing current and 10 % of the peak value during the decrease of
the continuing current (see Figure A.2)
3.17
flash charge
Q
flash
time integral of the lightning current for the entire lightning flash duration
3.18
short stroke charge
Q
short
time integral of the lightning current in a short stroke
3.19
long stroke charge
Q
long
time integral of the lightning current in a long stroke
3.20
specific energy
W/R
time integral of the square of the lightning current for the entire flash duration
NOTE It represents the energy dissipated by the lightning current in a unit resistance.
3.21
specific energy of short stroke current
time integral of the square of the lightning current for the duration of the short stroke
NOTE The specific energy in a long stroke current is negligible.

62305-1 © IEC:200662305-1  IEC:2006 – 21 – – 11 –
3.22
object to be protected
structure or service to be protected against the effects of lightning
3.23
structure to be protected
structure for which protection is required against the effects of lightning in accordance with this
standard
NOTE A structure to be protected may be a part of a larger structure.
3.24
service to be protected
service connected to a structure for which protection is required against the effects of lightning
in accordance with this standard
3.25
lightning flash to an object
lightning flash striking an object to be protected
3.26
lightning flash near an object
lightning flash striking close enough to an object to be protected that it may cause dangerous
overvoltages
3.27
electrical system
system incorporating low voltage power supply components
3.28
electronic system
system incorporating sensitive electronic components such as communication equipment,
computer, control and instrumentation systems, radio systems, power electronic installations
3.29
internal systems
electrical and electronic systems within a structure
3.30
physical damage
damage to a structure (or to its contents) or to a service due to mechanical, thermal, chemical
and explosive effects of lightning
3.31
injury of living beings
injuries, including loss of life, to people or to animals due to touch and step voltages caused by
lightning
3.32
failure of electrical and electronic systems
permanent damage of electrical and electronic systems due to LEMP

62305-1  IEC:2006 – 23 – – 12 – 62305-1 © IEC:2006
3.33
lightning electromagnetic impulse
LEMP
electromagnetic effects of lightning current
NOTE It includes conducted surges as well as radiated impulse electromagnetic field effects.
3.34
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 remaining threat downstream of SPD.
3.35
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).
3.36
risk
R
value of probable average annual loss (humans and goods) due to lightning, relative to the total
value (humans and goods) of the object to be protected
3.37
tolerable risk
R
T
maximum value of the risk which can be tolerated for the object to be protected
3.38
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.
3.39
protection measures
measures to be adopted in the object to be protected to reduce the risk
3.40
lightning protection system
LPS
complete system used to reduce physical damage due to lightning flashes to a structure
NOTE It consists of both external and internal lightning protection systems.
3.41
external lightning protection system
part of the LPS consisting of an air-termination system, a down-conductor system and an
earth-termination system
62305-1 © IEC:200662305-1  IEC:2006 – 25 – – 13 –
3.42
internal lightning protection system
part of the LPS consisting of lightning equipotential bonding and/or electrical insulation of
external LPS
3.43
air-termination system
part of an external LPS using metallic elements such as rods, mesh conductors or catenary
wires intended to intercept lightning flashes
3.44
down-conductor system
part of an external LPS intended to conduct lightning current from the air-termination system to
the earth-termination system
3.45
earth-termination system
part of an external LPS which is intended to conduct and disperse lightning current into the
earth
3.46
external conductive parts
extended metal items entering or leaving the structure to be protected such as pipe works,
cable metallic elements, metal ducts, etc. which may carry a part of the lightning current
3.47
lightning equipotential bonding
bonding to LPS of separated metallic parts, by direct conductive connections or via surge
protective devices, to reduce potential differences caused by lightning current
3.48
shielding wire
metallic wire used to reduce physical damage due to lightning flashes to a service
3.49
LEMP protection measures system
LPMS
complete system of protection measures for internal systems against LEMP
3.50
magnetic shield
closed, metallic, grid-like or continuous screen enveloping the object to be protected, or part of
it, used to reduce failures of electrical and electronic systems
3.51
surge protective device
SPD
device intended to limit transient overvoltages and divert surge currents. It contains at least
one non linear component
3.52
coordinated SPD protection
set of SPD properly selected, coordinated and erected to reduce failures of electrical and
electronic systems
62305-1  IEC:2006 – 27 – – 14 – 62305-1 © IEC:2006
3.53
rated impulse withstand voltage
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.
[1]
(IEC 60664-1:2002)
3.54
conventional earthing impedance
ratio of the peak values of the earth-termination voltage and the earth-termination current
which, in general, do not occur simultaneously
4 Lightning current parameters
The lightning current parameters used in the IEC 62305 series are given in Annex A.
The time function of the lightning current to be used for analysis purposes is given in Annex B.
Information for simulation of lightning current for test purposes is given in Annex C.
The basic parameters to be used in laboratory to simulate the effects of lightning on LPS
components are given in Annex D.
Information on surges due to lightning at different installation points is given in Annex E.
5 Damage due to lightning
5.1 Damage to a structure
Lightning affecting a structure can cause damage to the structure itself and to its occupants
and contents, including failure of internal systems. The damages and failures may also extend
to the surroundings of the structure and even involve the local environment. The scale of this
extension depends on the characteristics of the structure and on the characteristics of the
lightning flash.
5.1.1 Effects of lightning on a structure
The main characteristics of structures relevant to lightning effects include:
− construction (e.g. wood, brick, concrete, reinforced concrete, steel frame construction);
− function (dwelling house, office, farm, theatre, hotel, school, hospital, museum, church,
prison, department store, bank, factory, industry plant, sports area);
− occupants and contents (persons and animals, presence of combustible or non-combustible
materials, explosive or non-explosive materials, electrical and electronic systems with low or
high withstand voltage);
___________
References in square brackets refer to the bibliography.

62305-1 © IEC:200662305-1  IEC:2006 – 29 – – 15 –
− connected services (power lines, telecommunication lines, pipelines);
− existing or provided protection measures (e.g. protection measures to reduce physical
damage and life hazard, protection measures to reduce failure of internal systems);
− scale of the extension of danger (structure with difficulty of evacuation or structure where
panic may be created, structure dangerous to the surroundings, structure dangerous to the
environment).
Table 1 reports the effects of lightning on various types of structures.
Table 1 – Effects of lightning on typical structures
Type of structure
according to
Effects of lightning
function and/or
contents
Dwelling-house Puncture of electrical installations, fire and material damage
Damage normally limited to objects exposed to the point of strike or to the lightning current
path
Failure of electrical and electronic equipment and systems installed (e.g. TV sets,
computers, modems, telephones, etc.)
Farm building Primary risk of fire and hazardous step voltages as well as material damage
Secondary risk due to loss of electric power, and life hazard to livestock due to failure of
electronic control of ventilation and food supply systems, etc.
Theatre, Damage to the electrical installations (e.g. electric lighting) likely to cause panic
Hotel, Failure of fire alarms resulting in delayed fire fighting measures
School
Department store
Sports area
Bank As above, plus problems resulting from loss of communication, failure of computers and loss
of data
Insurance company
Commercial
company, etc.
Hospital As above, plus problems of people in intensive care, and the difficulties of rescuing immobile
people
Nursing home
Prison
Industry Additional effects depending on the contents of factories, ranging from minor to unacceptable
damage and loss of production
Museums and Loss of irreplaceable cultural heritage
archeological sites
Church
Telecommunications Unacceptable loss of services to the public
Power plants
Firework factory Consequences of fire and explosion to the plant and its surroundings
Munition works
Chemical plant Fire and malfunction of the plant with detrimental consequences to the local and global
environment
Refinery
Nuclear plant
Biochemical
laboratories and
plants
62305-1  IEC:2006 – 31 – – 16 – 62305-1 © IEC:2006
5.1.2 Sources and types of damage to a structure
The lightning current is the source of damage. The following situations shall be taken into
account, depending on the position of the point of strike relative to the structure considered:
− S1: flashes to the structure;
− S2: flashes near the structure;
− S3: flashes to the services connected to the structure;
− S4: flashes near the services connected to the structure.
Flashes to the structure can cause:
– immediate mechanical damage, fire and/or explosion due to the hot lightning plasma arc
itself, due to the current resulting in ohmic heating of conductors (over-heated conductors),
or due to the charge resulting in arc erosion (melted metal);
– fire and/or explosion triggered by sparks caused by overvoltages resulting from resistive
and inductive coupling and to passage of part of the lightning currents;
– injury to people by step and touch voltages resulting from resistive and inductive coupling;
– failure or malfunction of internal systems due to LEMP.
Flashes near the structure can cause:
– failure or malfunction of internal systems due to LEMP.
Flashes to a service connected to the structure can cause:
– fire and/or explosion triggered by sparks due to overvoltages and lightning currents
transmitted through the connected service;
– injury to people due to touch voltages inside the structure caused by lightning currents
transmitted through the connected service;
– failure or malfunction of internal systems due to overvoltages appearing on connected lines
and transmitted to the structure.
Flashes near a service connected to the structure can cause:
– failure or malfunction of internal systems due to overvoltages induced on connected lines
and transmitted to the structure.
NOTE 1 Malfunctioning of internal systems is not covered by the IEC 62305 series. Reference should be made to
[2]
IEC 61000-4-5 .
NOTE 2 Only the sparks carrying lightning current (total or partial) are regarded as able to trigger fire.
NOTE 3 Lightning flashes, direct to or near the incoming pipelines, do not cause damages to the structure,
provided that they are bonded to the equipotential bar of the structure (see IEC 62305-3).
As result, the lightning can cause three basic type of damages:
− D1: injury of living beings due to touch and step voltages;
− D2: physical damage (fire, explosion, mechanical destruction, chemical release) due to
lightning current effects including sparking;
− D3: failure of internal systems due to LEMP.

62305-1 © IEC:200662305-1  IEC:2006 – 33 – – 17 –
5.2 Damage to a service
Lightning affecting a service can cause damage to the physical means itself (line or pipe) used
to provide the service, as well as to connected electrical and electronic equipment.
NOTE The service to be considered is the physical connection between
– the switch telecommunication building and the user’s building or two switch telecommunication buildings or two
users’ buildings, for the telecommunication (TLC) lines,
– the switch telecommunication building or the user`s building and a distribution node, or two distribution nodes for
the telecommunication (TLC) lines,
– the high voltage (HV) substation and the user’s building, for the power lines,
– the main distribution station and the user’s building, for pipes.
The scale of this extension depends on the characteristics of the service, on the type and
extension of the electrical and electronic systems and on the characteristics of the lightning
flash.
5.2.1 Effects of lightning on a service
The main characteristics of services relevant to lightning effects include:
– construction (line: overhead, underground, screened, unscreened, fibre optic; pipe: above
ground, buried, metallic, plastic);
– function (telecommunication line, power line, pipeline);
– structure supplied (construction, contents, dimensions, location);
– existing or provided protection measures (e.g. shielding wire, SPD, route redundancy, fluid
storage systems, generating sets, uninterruptible power systems).
Table 2 reports the effects of lightning on various types of services.
Table 2 – Effects of lightning on typical services
Type of service Effects of lightning
Telecommunication line Mechanical damage to line, melting of screens and conductors,
breakdown of insulation of cable and equipment leading to a primary
failure with immediate loss of service
Secondary failures on the optical fibre cables with damage of the cable
but without loss of service
Power lines Damages to insulators of low voltage overhead line, puncturing of
insulation of cable line, breakdown of insulation of line equipment and of
transformers, with consequential loss of service
Water pipes Damages to electrical and electronic control equipments likely to cause
loss of service
Gas pipes Puncturing of non-metallic flange gaskets likely to cause fire and/or
explosion.
Fuel pipes
Damage to electrical and electronic control equipments likely to cause
loss of service
5.2.2 Sources and types of damage to a service
The lightning current is the source of damage. The following situations shall be taken into
account, depending on the position of the point of strike relative to the service considered:
− S1: flashes to the supplied structure;
− S3: flashes to the service connected to the structure;
− S4: flashes near the service connected to the structure.

62305-1  IEC:2006 – 35 – – 18 – 62305-1 © IEC:2006
Flashes to the supplied structure can cause:
– melting of metallic wires and of cable screens due to parts of the lightning current flowing
into the services (resulting from resistive heating);
– breakdown of insulation of lines and of the connected equipments (due to the resistive
coupling);
– puncturing of non-metallic gaskets in flanges of pipes, as well as gaskets in insulating
joints.
NOTE 1 Optical fibre cable without metallic conductor are not affected by lightning flashes striking the supplied
structure.
Flashes to a service connected to the structure can cause:
– immediate mechanical damage of metallic wires or piping due to electrodynamic stress or
heating effects caused by lightning current (breaking and/or melting of metallic wires,
screens or piping), and due to the heat of the lightning plasma arc itself (puncturing of
plastic protective cover);
– immediate electrical damage of lines (breakdown of insulation) and of connected
equipment;
– puncturing of thin overhead metallic pipes and of non-metallic gaskets in flanges, where
consequences may extend to fire and explosion depending on the nature of conveyed
fluids.
Flashes near a service connected to the structure can cause:
– breakdown of insulation of lines and of the connected equipments due to inductive coupling
(induced overvoltages).
NOTE 2 Optical fibre cable without metallic conductors are not affected by lightning flashes striking the ground.
As a result, the lightning can cause two basic type of damage:
– D2: physical damage (fire, explosion, mechanical destruction, chemical release) due to
thermal effects of lightning current
– D3: failure of electrical and electronic systems due to overvoltages.
5.3 Types of loss
Each type of damage, alone or in combination with others, may produce different consequential
loss in the object to be protected. The type of loss that may appear depends on the
characteristics of the object itself.
For the purposes of this standard the following types of loss are considered:
− L1: loss of human life;
− L2: loss of service to the public;
− L3: loss of cultural heritage;
− L4: loss of economical value (structure and its content, service and loss of activity).
Loss of type L1, L2 and L3 may be considered as loss of social values, whereas loss of type L4
may be considered as purely economical loss.
Losses which may appear in a structure are as follows:
− L1: loss of human life;
− L2: loss of service to the public;

62305-1 © IEC:200662305-1  IEC:2006 – 37 – – 19 –
− L3: loss of cultural heritage
− L4: loss of economic value (structure and its content).
Losses which may appear in a service are as follows:
− L2: loss of service to the public;
− L4: loss of economic value (service and loss of activity).
NOTE In a service, loss of human life is not considered in this standard.
The relationship between source of damage, type of damage and loss is reported in Table 3 for
structures and in Table 4 for services.
Table 3 – Damages and loss in a structure according to
different points of strike of lightning
Source of Type of
Point of strike Type of loss
damage damage
**
L1 L4
D1
,
Structure S1 D2 L1, L2, L3, L4
*
D3 L1 , L2, L4
*
Near a structure S2 D3 L1 , L2, L4

**
L1, L4
D1
Service connected to
S3
D2
the structure
L1, L2, L3, L4
D3
L1*, L2, L4
*
Near a service S4 D3 L1 , L2, L4

* Only for structures with risk of explosion and for hospitals or other structures where failure of internal systems
immediately endangers human life.
** Only for properties where animals may be lost.

Table 4 – Damages and loss in a service according to different points of strike of
lightning
Point of strike Source of damage Type of damage Type of loss
D2
Service S3
D3
Near the service S4 D3 L2, L4
D2
Supplied structure S1
D3
62305-1  IEC:2006 – 39 – – 20 – 62305-1 © IEC:2006
Types of loss resulting from types of damage and the corresponding risks are reported in
Figure 1.
Risk
Risk Risk Risk
1)
1)
R
R R
R  4
1 2 3
Loss of
Loss of
Loss of Loss of
Type of cultural
human
service to economic
loss heritage
life
the public values
2)
Failure of Failure of 3) Failure of
Injury of
Injury of
electrical electrical Physical Physical electrical
Type of Physical Physical
living
living
and and damage damage and
damage damage
damage
beings
beings
electronic electronic electronic
systems systems systems
IEC  2061/05
1)
Only for structures.
2)
Only for hospitals or other structures where failure on internal systems immediately endanger human life.
3)
Only for properties where animals may be lost.
Figur
...