EN 62305-2:2006

STANDARDZaščita pred delovanjem strele – 2. del: Vodenje tveganja (vključuje program za oceno tveganja)Protection against lightning - Part 2: Risk management©
Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljenoReferenčna številkaSIST EN 62305-2:2006(en)ICS91.120.40

EUROPEAN STANDARD EN 62305-2 NORME EUROPÉENNE
EUROPÄISCHE NORM February 2006
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 62305-2:2006 E
ICS 29.020; 91.120.40
English version
Protection against lightning Part 2: Risk management (IEC 62305-2:2006)
Protection contre la foudre Partie 2: Evaluation du risque (CEI 62305-2:2006)
Blitzschutz Teil 2: Risiko-Management (IEC 62305-2:2006)
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.

EN 62305-2:23006
- 2 - Foreword The text of document 81/263/FDIS, future edition 1 of IEC 62305-2, prepared by IEC TC 81, Lightning protection, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62305-2 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 62305-2:2006 was approved by CENELEC as a European Standard without any modification. __________

IEC 62305-2Edition 1.0 2006-01INTERNATIONAL STANDARD NORME INTERNATIONALEProtection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Evaluation des risques
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE XEICS 29.020;
91.120.40 PRICE CODECODE PRIXISBN 2-8318-8364-4

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CONTENTS
FOREWORD.7 INTRODUCTION.9
1 Scope.11 2 Normative references .11 3 Terms, definitions, symbols and abbreviations.11 4 Explanation of terms.21 4.1 Damage and loss .21 4.2 Risk and risk components.23 4.3 Composition of risk components related to a structure.25 4.4 Composition of risk components related to a service .27 4.5 Factors influencing the risk components.28 5 Risk management.29 5.1 Basic procedure .29 5.2 Structure to be considered for risk assessment .29 5.3 Service to be considered for risk assessment.29 5.4 Tolerable risk RT .30 5.5 Specific procedure to evaluate the need of protection.30 5.6 Procedure to evaluate the cost effectiveness of protection .31 5.7 Protection measures .33 5.8 Selection of protection measures.33 6 Assessment of risk components for a structure.36 6.1 Basic equation.36 6.2 Assessment of risk components due to flashes to the structure (S1).36 6.3 Assessment of the risk component due to flashes near the structure (S2) .36 6.4 Assessment of risk components due to flashes to a line connected to the structure (S3) .37 6.5 Assessment of risk component due to flashes near a line connected to the structure (S4) .37 6.6 Summary of risk components in a structure .39 6.7 Partitioning of a structure in zones ZS .39 6.8 Assessment of risk components in a structure with zones ZS.40 7 Assessment of risk components for a service .41 7.1 Basic equation.41 7.2 Assessment of components due to flashes to the service (S3).41 7.3 Assessment of risk component due to flashes near the service (S4).41 7.4 Assessment of risk components due to flashes to structures to which the service is connected (S1) .42 7.5 Summary of risk components for a service .42 7.6 Partitioning of a service into sections SS .43
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Annex A (informative)
Assessment of annual number N of dangerous events.44 Annex B
(informative)
Assessment of probability PX of damage for a structure.53 Annex C (informative)
Assessment of amount of loss LX in a structure.59 Annex D (informative)
Assessment of probability P′X of damage to a service .64 Annex E (informative)
Assessment of the amount of loss L′X in a service.68 Annex F (informative)
Switching overvoltages.70 Annex G (informative)
Evaluation of costs of loss .71 Annex H (informative)
Case study for structures .72 Annex I (informative)
Case study for services – Telecommunication line.99 Annex J (informative)
Simplified software for risk assessment for structures.105
Bibliography.110
Figure 1 – Procedure for deciding the need of protection .31 Figure 2 – Procedure for evaluating the cost-effectiveness of protection measures.32 Fiigure 3 – Procedure for selecting protection measures in structures.34 Figure 4 – Procedure for selecting protection measures in services .35 Figure 5 – Structures at line ends: at “b” end the structure to be protected
(structure b) and at “a” end an adjacent structure(structure a) .38 Figure A.1 – Collection area Ad of an isolated structure .45 Figure A.2 – Complex shape structure .46 Figure A.3 – Different methods to determine the collection area
for the structure of Figure A.2.47 Figure A.4 – Structure to be considered for evaluation of collection area Ad .48 Figure A.5 – Collection areas (Ad, Am, Ai, Al).52 Figure I.1 – Telecommunication line to be protected .99 Figure J.1 – Example for a country house (see Clause H.1 – no protection measures provided) .108 Figure J.2 – Example for a country house (see Clause H.1 – protection measures provided) .109
Table 1 – Sources of damage, types of damage and types of loss selected
according to the point of strike.22 Table 2 – Risk in a structure for each type of damage and of loss.23 Table 3 – Risk components to be considered for each type of loss in a structure .26 Table 4 – Risk components to be considered for each type of loss in a service.27 Table 5 – Factors influencing the risk components in a structure .28 Table 6 – Factors influencing the risk components in a service.29 Table 7 – Typical values of tolerable risk RT .30 Table 8 – Parameters relevant to the assessment of risk components for a structure.38 Table 9 – Risk components for a structure for different types of damage
caused by different sources.39 62305-2 © IEC:2006– 3 –

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Table 10 – Parameters relevant to the assessment of risk components for a service.42 Table 11 – Risk components for a service for different types of damage
caused by different sources.43 Table A. 1 – Values of collection area depending on the evaluation method.46 Table A.2 – Location factor Cd .49 Table A.3 – Collection areas Al and Ai depending on the service characteristics.50 Table A.4 – Transformer factor Ct .51 Table A.5 – Environmental factor Ce .51 Table B.1 – Values of probability PA that a flash to a structure will cause shock
to living beings due to dangerous touch and step voltages.53 Table B.2 – Values of PB depending on the protection measures to reduce physical damage .54 Table B.3 – Value of the probability PSPD as a function of LPL
for which SPDs are designed.54 Table B.4 – Value of the probability PMS as a function of factor KMS .55 Table B.5 – Value of factor KS3 depending on internal wiring .56 Table B.6 – Values of the probability PLD depending on the resistance RS of the cable screen and the impulse withstand voltage Uw of the equipment .57 Table B.7 – Values of the probability PLI depending on the resistance RS of the cable screen and the impulse withstand voltage Uw of the equipment .58 Table C.1 – Typical mean values of Lt, Lf and Lo.60 Table C.2 – Values of reduction factors ra and ru as a function
of the type of surface of soil or floor .60 Table C.3 – Values of reduction factor rp as a function of provisions taken
to reduce the consequences of fire.61 Table C.4 – Values of reduction factor rf as a function of risk of fire of structure .61 Table C.5 – Values of factor h increasing the relative amount of loss
in presence of a special hazard .61 Table C.6 – Typical mean values of Lf and Lo .62 Table C.7 – Typical mean values of Lt, Lf and Lo .63 Table D.1 – Values of factor Kd as function of the characteristics of the shielded line .64 Table D.2 – Values of the factor Kp as function of the protection measures.65 Table D.3 – Impulse withstand voltage Uw as a function of the type of cable.65 Table D.4 – Impulse withstand voltage Uw as a function of the type of apparatus.65 Table D.5 – Values of probability P′B, P′C, P′V and P′W as function of
the failure current Ia .66 Table E.1 – Typical mean values of L′f and L′o.68 Table H.1 – Structure data and characteristics.72 Table H.2 – Data and characteristics of lines and connected internal systems .73 Table H.3 – Zone Z2 (inside the building) characteristics .74 Table H.4 – Collection areas of structure and lines .74 Table H.5 – Expected annual number of dangerous events.75 Table H.6 – Risk components involved and their calculation (values x 10–5) .75 – 4 –62305-2 © IEC:2006

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Table H.7 – Values of risk components relevant to risk R1 (values × 10–5)
for suitable cases.77 Table H.8 – Structure characteristics .77 Table H.9 – Internal power system and connected power line characteristics.78 Table H.10 – Internal telecom system and connected TLC line characteristics.78 Table H.11 – Zone Z1 (entrance area to the building) characteristics .79 Table H.12 – Zone Z2 (garden) characteristics.79 Table H.13 – Zone Z3 (archive) characteristics .79 Table H.14 – Zone Z4 (offices) characteristics .80 Table H.15 – Zone Z5 (computer centre) characteristics.80 Table H.16 – Collection areas of structure and lines .80 Table H.17 – Expected annual number of dangerous events.81 Table H.18 – Risk R1- Values of risk components according to zones (values × 10–5).81 Table H.19 –Composition of risk R1 components according to zones (values × 10–5).81 Table H.20 – Values of risk R1 according to solution chosen (values × 10–5) .82 Table H.21 – Structure characteristics .83 Table H.22 – Internal power system and relevant incoming power line characteristics .84 Table H.23 – Internal telecom system and relevant incoming line characteristics .84 Table H.24 – Zone Z1 (outside building) characteristics .85 Table H.25 – Zone Z2 (rooms block) characteristics.86 Table H.26 – Zone Z3 (operating block) characteristics.86 Table H.27 – Zone Z4 ( intensive care unity) characteristics.87 Table H.28 – Expected annual number of dangerous events.87 Table H.29 – Risk R1 – Risk components to be considered according to zones.88 Table H.30 – Risk R1 – Values of probability P for unprotected structure .88 Table H.31 – Risk R1 – Values of risk components for unprotected structure
according to zones (values × 10–5) .89 Table H.32 – Composition of risk R1 components according to zones (values × 10–5) .89 Table H.33 – Risk R1– Values of probability P for the protected structure
according to solution a).91 Table H.34 – Risk R1 – Values of probability P for protected structure
according to solution b).91 Table H.35 – Risk R1 – Values of probability P for the protected structure
according to solution c).92 Table H.36 – Risk R1 – Values of risk according to solution chosen (values × 10–5).92 Table H.37 – Values of costs of loss relevant to zones (values in $ ×106).93 Table H.38 – Values relevant to rates .93 Table H.39 – Risk R4 – Values of risk components for unprotected structure
according to zones (values ×10–5) .94 62305-2 © IEC:2006– 5 –

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Table H.40 – Amount of losses CL and CRL (values in $) .94 Table H.41 – Costs CP and CPM of protection measures (values in $).95 Table H.42 – Annual saving of money (values in $).95 Table H.43 – Structure characteristics .96 Table H.44 – Zone Z2 parameters.96 Table H.45 – Internal power system and relevant incoming line parameters.97 Table H.46 – Internal telecom system and relevant incoming line parameters.97 Table H.47 – Protection measures to be adopted according to the height of the building and its risk of fire.98 Table I.1 – Section S1 of line characteristics.100 Table I.2 – Section S2 of line characteristics.100 Table I.3 – End of line structure characteristics.101 Table I.4 – Expected annual number of dangerous events .101 Table I.5 – Risk R′2- Risk components relevant to sections S of the line.101 Table I.6 – Risk R′2- Values of failure currents and probabilities P′ for unprotected line.102 Table I.7 – Risk R′2- Values of risk components for unprotected line
according to sections S of the line (values × 10–3) .103 Table I.8 – Risk R′2- Values of probabilities P′ for the protected line.104 Table I.9 – Risk R′2- Values of risk components for the line protected with SPDs installed in the transition point T1/2 and Ta with PSPD = 0,03 (values × 10–3).104 Table J.1 – Parameters for the user to change freely.105 Table J.2 – Limited subset of parameters to be changed by the user .105 Table J.3 – Fixed parameters (not to altered by the user) .107
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INTERNATIONAL ELECTROTECHNICAL COMMISSION ___________
PROTECTION AGAINST LIGHTNING –
Part 2: Risk management
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 62305-2 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 62305-2 is compiled from and replaces – IEC 61662, first edition (1995) and its Amendment (1996). – 7 –62305-2 © IEC:2006

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The text of this standard is based on the following documents: FDIS Report on voting 81/263/FDIS 81/268/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:
Services1
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. ___________ 1 To be published 62305-2 © IEC:2006– 8 –

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INTRODUCTION Lightning flashes to earth may be hazardous to structures and to services. The hazard to a structure can result in – damage to the structure and to its contents, – failure of associated electrical and electronic systems, – injury to living beings in or close to the structure.
Consequential effects of the damage and failures may be extended to the surroundings of the structure or may involve its environment. The hazard to services can result in – damage to the service itself, – failure of associated electrical and electronic equipment. To reduce the loss due to lightning, protection measures may be required. Whether they are needed, and to what extent, should be determined by risk assessment.
The risk, defined in this standard as the probable average annual loss in a structure and in a service due to lightning flashes, depends on: – the annual number of lightning flashes influencing the structure and the service;
– the probability of damage by one of the influencing lightning flashes; – the mean amount of consequential loss.
Lightning flashes influencing the structure may be divided into – flashes terminating on the structure, – flashes terminating near the structure, direct to connected services (power, telecom-munication lines, other services) or near the services.
Lightning flashes influencing the service may be divided into – flashes terminating on the service, – flashes terminating near the service or direct to a structure connected to the service. Flashes to the structure or a connected service may cause physical damage and life hazards. Flashes near the structure or service as well as flashes to the structure or service may cause failure of electrical and electronic systems due to overvoltages resulting from resistive and inductive coupling of these systems with the lightning current.
Moreover, failures caused by lightning overvoltages in users′ installations and in power supply lines may also generate switching type overvoltages in the installations. NOTE 1 Malfunctioning of electrical and electronic systems is not covered by the IEC 62305 series. Reference should be made to IEC 61000-4-5 [1]2. NOTE 2 Information on assessment of the risk due to switching overvoltages is given in Annex F. ___________ 2
Figures in square brackets refer to the bibliography. – 9 –62305-2 © IEC:2006

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The number of lightning flashes influencing the structure and the services depends on the dimensions and the characteristics of the structure and of the services, on the environment characteristics of the structure and the services, as well as on lightning ground flash density in the region where the structure and the services are located. The probability of lightning damage depends on the structure, the services, and the lightning current characteristics; as well as on the type and efficiency of applied protection measures. The annual mean amount of the consequential loss depends on the extent of damage and the consequential effects which may occur as result of a lightning flash.
The effect of protection measures results from the features of each protection measure and may reduce the damage probabilities or the amount of consequential loss.
The assessment of risk due to all possible effects of lightning flashes to structures and services is given in this standard, which is a revised version of IEC 61662:1995 and its Amendment 1:1996.
The decision to provide lightning protection may be taken regardless of the outcome of any risk assessment where there is a desire that there be no avoidable risk. 62305-2 © IEC:2006– 10 –

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PROTECTION AGAINST LIGHTNING –
Part 2: Risk management
1 Scope
This part of IEC 62305 is applicable to risk assessment for a structure or for a service due to lightning flashes to earth.
Its purpose is to provide a procedure for the evaluation of such a risk. Once an upper tolerable limit for the risk has been selected, this procedure allows the selection of appropriate protection measures to be adopted to reduce the risk to or below the tolerable limit. 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 60079-10:2002, Electrical apparatus for explosive gas atmosphere – Part 10: Classification of hazardous areas IEC 61241-10:2004, Electrical apparatus for use in the presence of combustible dust – Part 10: Classification of areas where combustible dusts are or may be present 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 IEC 62305-5, Protection against lightning – Part 5: Services3
ITU-T Recommendation K.46:2000, Protection of telecommunication lines using metallic symmetric conductors against lightning induced surges ITU-T Recommendation K.47:2000, Protection of telecommunication lines using metallic conductors against direct lightning discharges 3 Terms, definitions, symbols and abbreviations For the purposes of this document, the following terms, definitions, symbols and abbreviations, some of which have already been cited in Part 1 but are repeated here for ease of reading, as well as those given in other parts of IEC 62305, apply. ___________ 3 To be published – 11 –62305-2 © IEC:2006

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3.1 Terms and definitions 3.1.1 object to be protected
structure or service to be protected against the effects of lightning 3.1.2 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. 3.1.3 structures with risk of explosion structures containing solid explosives materials or hazardous zones as determined in accordance with IEC 60079-10 and IEC 61241-10 NOTE For the purposes of this standard, only structures with hazardous zones type 0 or containing solid explosive materials are considered. 3.1.4 structures dangerous to the environment structures which may cause biological, chemical and radioactive emission as a consequence of lightning (such as chemical, petrochemical, nuclear plants, etc). 3.1.5 urban environment area with a high density of buildings or densely populated communities with tall buildings NOTE ’Town centre’ is an example of an urban environment.
3.1.6 suburban environment area with a medium density of buildings NOTE ’Town outskirts’ is an example of a suburban environment.
3.1.7 rural environment area with a low density of buildings. NOTE ’Countryside’ is an example of a rural environment.
3.1.8
rated impulse withstand voltage level
Uw 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.
3.1.9 electrical system system incorporating low voltage power supply components
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3.1.10 electronic system system incorporating sensitive electronic components such as communication equipment, computer, control and instrumentation systems, radio systems, power electronic installations 3.1.11 internal systems electrical and electronic systems within a structure 3.1.12 service to be protected service connected to a structure for which protection is required against the effects of lightning in accordance with this standard 3.1.13
telecommunication lines transmission medium intended for communication between equipment that may be located in separate structures, such as phone line and data line 3.1.14
power lines transmission lines feeding electrical energy into a structure to power electrical and electronic equipment located there, such as low voltage (LV) or high voltage (HV) electric mains 3.1.15
pipes
piping intended to convey a fluid into or out of a structure, such as gas pipe, water pipe, oil pipe 3.1.16 dangerous event lightning flash to the object to be protected or near the object to be protected 3.1.17 lightning flash to an object lightning flash striking an object to be protected
3.1.18 lightning flash near an object
lightning flash striking close enough to an object to be protected that it may cause dangerous overvoltages 3.1.19 number of dangerous events due to flashes to a structure
ND expected average annual number of dangerous events due to lightning flashes to a structure 3.1.20 number of dangerous events due to flashes to a service
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3.1.21
number of dangerous events due to flashes near a structure
NM expected average annual number of dangerous events due to lightning flashes near a structure 3.1.22 number of dangerous events due to flashes near a service
NI expected average annual number of dangerous events due to lightning flashes near a service
3.1.23 lightning electromagnetic impulse
LEMP electromagnetic effects of lightning current
NOTE It includes conducted surges as well as radiated impulse electromagnetic field effects.
3.1.24 surge transient wave appearing as overvoltage and/or overcurrents caused by LEMP NOTE Surges caused by LEMP can arise from (partial) lightning currents, from induction effects into installation loops and as remaining threats downstream of SPD. 3.1.25 node point on a service line at a which surge propagation can be assumed to be neglected NOTE Examples of nodes are a point on a power line branch distribution at a HV/LV transformer, a multiplexer on a telecommunication line or SPD installed along the line conforming to IEC 62305-5.
3.1.26 physical damage damage to a structure (or to its contents) or to a service due to mechanical, thermal, chemical or explosive effects of lightning. 3.1.27 injury to living beings injuries, including loss of life, to people or to animals due to touch and step voltages caused by lightning
3.1.28 failure of electrical and electronic systems permanent damage of electrical and electronic systems due to LEMP 3.1.29 failure current
Ia minimum peak value of lightning current that will cause damage in a line 3.1.30 probability of damage PX
probability that a dangerous event will cause damage to or in the object to be protected
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3.1.31 loss
LX mean amount of loss (humans and goods) consequent to a specified type of damage due to a dangerous event, relative to the value (humans and goods) of the object to be protected
3.1.32 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
3.1.33
risk component
RX partial risk depending on the source and the type of damage
3.1.34 tolerable risk
RT maximum value of the risk which can be tolerated for the object to be protected 3.1.35 zone of a structure
ZS
part of a structure with homogeneous characteristics where only one set of parameters is involved in assessment of a risk component
3.1.36
section of a service SS part of a service with homogeneous characteristics where only one set of parameters is involved in the assessment of a risk component 3.1.37
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). 3.1.38
lightning protection level
LPL number related to a set of lightning current parameter 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.
3.1.39 protection measures measures to be adopted in the object to be protected, in order to reduce the risk
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3.1.40 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. 3.1.41
LEMP protection measures system
LPMS complete system of protection measures for internal systems against LEMP
3.1.42 shielding wire metallic wire used to reduce physical damage due to lightning flashes to a service 3.1.43
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 3.1.44 lightning protective cable special cable with increased dielectric strength, whose metallic sheath is in continuous contact with the soil either directly or by the use of conducting plastic covering 3.1.45 lightning protective cable duct cable duct of low resistivity in contact with the soil (for example, concrete with interconnected structural steel reinforcements or a metallic duct) 3.1.46 surge protective device
SPD device intended to limit transient overvoltages and divert surge currents. It contains at least one non-linear component 3.1.47
coordinated SPD protection set of SPDs properly selected, coordinated and installed to reduce failures of electrical and electronic systems 3.2 Symbols and abbreviations
a Amortization rate.Annex G Ad
Collection area for flashes to an isolated structure .A.2 Ad′
Collection area attributed to an elevated roof protrusion .A.2.1 Ai Collection area for flashes near a service.A.4; Table A.3 Al
Collection area for flashes to a service. A.4; Table A.3 Am
Area of influence for flashes near a structure.A.3
B
Building.A.2
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c
Mean value of possible loss of the structure, in currency .C.4; C.5 CA
Annual cost of the animals.Annex G CB
Annual cost of the building.Annex G CC Annual cost of the contents.Annex G Cd Location factor. A.2; Table A.2 Ce Environmental factor.A.5; Table A.5 CL
Annual cost of total loss in absence of protection measures.5.6; Annex G
CRL
Annual cost of residual loss.5.6; Annex G CP Cost of protection measures.Annex G CPM
Annual cost of selected protection measures.5.6; Annex G CS
Annual cost of systems in a structure. Annex G Ct Correction factor for a HV/LV transformer on the service. A.4;Table A.4 ct
Total value of the structure, in currency. C.4; C.5; E.3
Di Lateral distance relevant to lightning flash near a service .A.5 D1 Injury to living beings.4.1.2 D2 Physical damage .4.1.2 D3 Failure of electrical and electronic systems.4.1.2
hz
Factor increasing the loss when a special hazard is present.
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