IEC 62305-2:2010

Protection against lightning - Part 2: Risk management

IEC 62305-2:2010 is applicable to risk assessment for a structure 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. This second edition cancels and replaces the first edition, published in 2006, and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
1) Risk assessment for services connected to structures is excluded from the scope.
2) Injuries of living beings caused by electric shock inside the structure are considered.
3) Tolerable risk of loss of cultural heritage is lowered from 10-3 to 10-4. The value of tolerable risk of loss of economic value (RT = 10-3) is introduced, to be used when data for cost/benefit analysis are not available.
4) Extended damage to surroundings structures or to the environment is considered.
5) Improved equations are provided for evaluation of
- collection areas relevant to flashes nearby a structure,
- collection areas relevant to flashes to and nearby a line,
- probabilities that a flash can cause damage,
- loss factors even in structures with risk of explosion,
- risk relevant to a zone of a structure,
- cost of loss.
6) Tables are provided to select the relative amount of loss in all cases.
7) Impulse withstand voltage level of equipments was extended down to 1 kV.
This bilingual version corresponds to the monolingual English version, published in 2010-12.

Protection contre la foudre - Partie 2: Evaluation des risques

La CEI 62305-2:2010 est applicable à l'évaluation des risques, dans une structure, en raison des coups de foudre au sol. Elle est destinée à proposer une procédure d'évaluation d'un tel risque. Une fois fixée la limite supérieure du risque tolérable, la procédure proposée permet de choisir les mesures de protection appropriées pour réduire le risque à une valeur inférieure ou égale à la valeur limite tolérable. Cette deuxième édition annule et remplace la première édition, publiée en 2006, et constitue une révision technique. Par rapport à la précédente, cette édition comprend les modifications techniques significatives suivantes:
1) L'évaluation des risques pour les services connectés aux structures est exclue du domaine d'application.
2) Les blessures aux êtres vivants dues au choc électrique à l'intérieur de la structure sont prises en compte.
3) Le risque tolérable de perte du patrimoine culturel est réduit de 10-3 à 10-4. La valeur du risque tolérable de perte de valeur économique (RT = 10-3) est introduite pour être utilisée lorsque les données applicables à l'analyse de rentabilité ne sont pas disponibles.
4) Les dommages étendus aux structures avoisinantes ou à l'environnement sont pris en compte.
5) Des équations améliorées sont fournies pour l'évaluation des éléments suivants:
- surfaces équivalentes d'exposition pour les coups de foudre à proximité d'une structure;
- surfaces équivalentes d'exposition pour les coups de foudre sur et à proximité d'un service;
- probabilités qu'un coup de foudre puisse provoquer des dommages;
- facteurs de pertes même dans des structures avec risque d'explosion;
- risque valable pour une zone d'une structure;
- coût des pertes.
6) Les tableaux sont fournis pour sélectionner le coût relatif des pertes dans tous les cas.
7) Le niveau de tension de tenue aux chocs des matériels a été porté jusqu'à 1 kV.
La présente version bilingue correspond à la version anglaise monolingue publiée en 2010-12.

General Information

• Status: Published
• Publication Date: 08-Dec-2010
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.020 - Electrical engineering in general
• ICS: 91.120.40 - Lightning protection
• Technical Committee: TC 81 - Lightning protection

Relations

• Revised: IEC 62305-2:2024 - Protection against lightning - Part 2: Risk management
• Effective Date: 05-Sep-2023
• Revises: IEC 62305-2:2006 - Protection against lightning - Part 2: Risk management
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 62305-2 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
colour
inside
Protection against lightning –
Part 2: Risk management
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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IEC 62305-2 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
colour
inside
Protection against lightning –
Part 2: Risk management
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.020; 91.120.40 ISBN 978-2-88912-281-3
– 2 – 62305-2 Ó IEC:2010(E)
CONTENTS
FOREW ORD . 6
INTRODUCTION . 8
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, symbols and abbreviations . 10
3.1 Terms and definitions . 10
3.2 Symbols and abbreviations . 16
4 Explanation of terms . 19
4.1 Damage and loss . 19
4.1.1 Source of damage . 19
4.1.2 Types of damage . 19
4.1.3 Types of loss . 19
4.2 Risk and risk components . 20
4.2.1 Risk . 20
4.2.2 Risk components for a structure due to flashes to the structure . 21
4.2.3 Risk component for a structure due to flashes near the structure. 21
4.2.4 Risk components for a structure due to flashes to a line connected to
the structure . 21
4.2.5 Risk component for a structure due to flashes near a line connected
to the structure . 21
4.3 Composition of risk components . 22
5 Risk management . 23
5.1 Basic procedure . 23
5.2 Structure to be considered for risk assessment . 23
5.3 Tolerable risk R . 24
T
5.4 Specific procedure to evaluate the need of protection . 24
5.5 Procedure to evaluate the cost effectiveness of protection . 25
5.6 Protection measures. 28
5.7 Selection of protection measures . 28
6 Assessment of risk components . 28
6.1 Basic equation . 28
6.2 Assessment of risk components due to flashes to the structure (S1) . 29
6.3 Assessment of the risk component due to flashes near the structure (S2) . 29
6.4 Assessment of risk components due to flashes to a line connected to the
structure (S3) . 29
6.5 Assessment of risk component due to flashes near a line connected to the
structure (S4) . 30
6.6 Summary of risk components . 31
6.7 Partitioning of a structure in zones Z . 31
S
6.8 Partitioning of a line into sections S . 32
L
6.9 Assessment of risk components in a structure with zones Z . 32
S
6.9.1 General criteria . 32
6.9.2 Single zone structure . 32
6.9.3 Multi-zone structure . 32
6.10 Cost-benefit analysis for economic loss (L4) . 33
Annex A (informative) Assessment of annual number N of dangerous events . 34
Annex B (informative) Assessment of probability P of damage . 42
X
62305-2 Ó IEC:2010(E) – 3 –
Annex C (informative) Assessment of amount of loss L . 50
X
Annex D (informative) Evaluation of costs of loss . 57
Annex E (informative) Case study . 58
Bibliography . 84

Figure 1 – Procedure for deciding the need of protection and for selecting protection
measures . 26
Figure 2 – Procedure for evaluating the cost-effectiveness of protection measures . 27
Figure A.1 – Collection area A of an isolated structure . 35
D
Figure A.2 – Complex shaped structure . 36
Figure A.3 – Different methods to determine the collection area for the given structure . 37
Figure A.4 – Structure to be considered for evaluation of collection area A . 38
D
Figure A.5 – Collection areas (A A , A , A ) . 41
D, M I L
Figure E.1 – Country house . 58
Figure E.2 – Office building . 63
Figure E.3 – Hospital . 69
Figure E.4 – Apartment block . 80

Table 1 – Sources of damage, types of damage and types of loss according to the
point of strike . 20
Table 2 – Risk components to be considered for each type of loss in a structure . 22
Table 3 – Factors influencing the risk components . 23
Table 4 – Typical values of tolerable risk R . 24
T
Table 5 – Parameters relevant to the assessment of risk components . 30
Table 6 – Risk components for different types of damage and source of damage . 31
Table A.1 – Structure location factor C . 39
D
Table A.2 – Line installation factor C . 40
I
Table A.3 – Line type factor C . 40
T
Table A.4 – Line environmental factor C . 40
E
Table B.1 – Values of probability P that a flash to a structure will cause shock to
TA
living beings due to dangerous touch and step voltages . 42
Table B.2 – Values of probability P depending on the protection measures to reduce
B
physical damage . 43
Table B.3 – Value of the probability P as a function of LPL for which SPDs are
SPD
designed . 44
Table B.4 – Values of factors C and C depending on shielding, grounding and
LD LI
isolation conditions . 44
Table B.5 – Value of factor K depending on internal wiring . 46
S3
Table B.6 – Values of probability P that a flash to an entering line will cause shock
TU
to living beings due to dangerous touch voltages . 47
Table B.7 – Value of the probability P as a function of LPL for which SPDs are
EB
designed . 47
Table B.8 – Values of the probability P depending on the resistance R of the cable
LD S
screen and the impulse withstand voltage U of the equipment . 47
W
Table B.9 – Values of the probability P depending on the line type and the impulse
LI
withstand voltage U of the equipment . 49
W
– 4 – 62305-2 Ó IEC:2010(E)
Table C.1 – Type of loss L1: Loss values for each zone . 51
Table C.2 – Type of loss L1: Typical mean values of L , L and L . 51
T F O
Table C.3 – Reduction factor r as a function of the type of surface of soil or floor . 52
t
Table C.4 – Reduction factor r as a function of provisions taken to reduce the
p
consequences of fire . 52
Table C.5 – Reduction factor r as a function of risk of fire or explosion of structure . 53
f
Table C.6 – Factor h increasing the relative amount of loss in presence of a special
z
hazard . 53
Table C.7 – Type of loss L2: Loss values for each zone . 54
Table C.8 – Type of loss L2: Typical mean values of L and L . 54
F O
Table C.9 – Type of loss L3: Loss values for each zone . 54
Table C.10 – Type of loss L3: Typical mean value of L . 55
F
Table C.11 – Type of loss L4: Loss values for each zone . 55
Table C.12 – Type of loss L4: Typical mean values of L , L and L . 56
T F O
Table E.1 – Country house: Environment and structure characteristics. 59
Table E.2 – Country house: Power line . 59
Table E.3 – Country house: Telecom line (TLC) . 59
Table E.4 – Country house: Factors valid for zone Z (inside the building).
...

IEC 62305-2 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Protection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Evaluation des risques

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
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International Standards for all electrical, electronic and related technologies.

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latest edition, a corrigenda or an amendment might have been published.
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IEC 62305-2 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Protection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Evaluation des risques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XC
ICS 29.020; 91.120.40 ISBN 978-2-88912-794-8

– 2 – 62305-2  IEC:2010
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, symbols and abbreviations . 10
3.1 Terms and definitions . 10
3.2 Symbols and abbreviations . 16
4 Explanation of terms . 19
4.1 Damage and loss . 19
4.1.1 Source of damage . 19
4.1.2 Types of damage . 19
4.1.3 Types of loss . 19
4.2 Risk and risk components . 20
4.2.1 Risk . 20
4.2.2 Risk components for a structure due to flashes to the structure . 21
4.2.3 Risk component for a structure due to flashes near the structure . 21
4.2.4 Risk components for a structure due to flashes to a line connected to
the structure . 21
4.2.5 Risk component for a structure due to flashes near a line connected
to the structure . 21
4.3 Composition of risk components . 22
5 Risk management . 23
5.1 Basic procedure . 23
5.2 Structure to be considered for risk assessment . 23
5.3 Tolerable risk R . 24
T
5.4 Specific procedure to evaluate the need of protection. 24
5.5 Procedure to evaluate the cost effectiveness of protection . 25
5.6 Protection measures . 27
5.7 Selection of protection measures. 28
6 Assessment of risk components . 28
6.1 Basic equation. 28
6.2 Assessment of risk components due to flashes to the structure (S1) . 28
6.3 Assessment of the risk component due to flashes near the structure (S2) . 29
6.4 Assessment of risk components due to flashes to a line connected to the

structure (S3) . 29
6.5 Assessment of risk component due to flashes near a line connected to the
structure (S4) . 30
6.6 Summary of risk components . 31
6.7 Partitioning of a structure in zones Z . 31
S
6.8 Partitioning of a line into sections S . 31
L
6.9 Assessment of risk components in a structure with zones Z . 32
S
6.9.1 General criteria . 32
6.9.2 Single zone structure . 32
6.9.3 Multi-zone structure . 32
6.10 Cost-benefit analysis for economic loss (L4). 33
Annex A (informative) Assessment of annual number N of dangerous events. 34
Annex B (informative) Assessment of probability P of damage . 42
X
62305-2  IEC:2010 – 3 –
Annex C (informative) Assessment of amount of loss L . 50
X
Annex D (informative) Evaluation of costs of loss. 57
Annex E (informative) Case study . 58
Bibliography . 85

Figure 1 – Procedure for deciding the need of protection and for selecting protection
measures . 26
Figure 2 – Procedure for evaluating the cost-effectiveness of protection measures . 27
Figure A.1 – Collection area A of an isolated structure . 35
D
Figure A.2 – Complex shaped structure . 36
Figure A.3 – Different methods to determine the collection area for the given structure. 37
Figure A.4 – Structure to be considered for evaluation of collection area A . 38
D
Figure A.5 – Collection areas (A A , A , A ) . 41
D, M I L
Figure E.1 – Country house . 58
Figure E.2 – Office building . 63
Figure E.3 – Hospital . 70
Figure E.4 – Apartment block . 81

Table 1 – Sources of damage, types of damage and types of loss according to the
point of strike . 20
Table 2 – Risk components to be considered for each type of loss in a structure . 22
Table 3 – Factors influencing the risk components . 23
Table 4 – Typical values of tolerable risk R . 24
T
Table 5 – Parameters relevant to the assessment of risk components . 30
Table 6 – Risk components for different types of damage and source of damage . 31
Table A.1 – Structure location factor C . 39
D
Table A.2 – Line installation factor C . 40
I
Table A.3 – Line type factor C . 40
T
Table A.4 – Line environmental factor C . 40
E
Table B.1 – Values of probability P that a flash to a structure will cause shock to
TA
living beings due to dangerous touch and step voltages . 42
Table B.2 – Values of probability P depending on the protection measures to reduce
B
physical damage . 43
Table B.3 – Value of the probability P as a function of LPL for which SPDs are
SPD
designed . 44
Table B.4 – Values of factors C and C depending on shielding, grounding and
LD LI
isolation conditions . 44
Table B.5 – Value of factor K
...