IEC 62305-2:2024
(Main)Protection against lightning - Part 2: Risk management
Protection against lightning - Part 2: Risk management
IEC 62305-2:2024 is applicable to the risk management of 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 provides a means for the selection of appropriate protection measures to be adopted to reduce the risk to or below the tolerable limit.
This third edition cancels and replaces the second edition, published in 2010. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) The concept of a single risk, to combine loss of human life and loss due to fire, has been introduced.
b) The concept of frequency of damage that can impair the availability of the internal systems within the structure has been introduced.
c) The lightning ground strike-point density NSG has been introduced replacing the lightning flash density NG in the evaluation of expected average annual number of dangerous events.
d) Reduction of a few risk components can be achieved by the use of preventive temporary measures activated by means of a thunderstorm warning system (TWS) compliant with IEC 62793. The risk of direct strike to people in open areas has been introduced, considering the reduction of that risk using a TWS.
The content of the corrigendum 1 (2024-10) has been included in this copy.
Protection contre la foudre - Partie 2: Évaluation des risques
L'IEC 62305-2:2024 s'applique à l'évaluation des risques auxquels une structure est exposée en raison des coups de foudre à la terre.
Elle est destinée à proposer une procédure d'évaluation d'un tel risque. Lorsque la limite supérieure du risque tolérable est fixée, la procédure permet de choisir les mesures de protection appropriées pour réduire le risque à une valeur inférieure ou égale à la valeur limite tolérable.
Cette troisième édition annule et remplace la deuxième édition parue en 2010. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) adoption du concept de risque unique, afin de combiner les pertes de vies humaines et les pertes dues à un incendie;
b) adoption du concept de fréquence des dommages qui peuvent influencer la disponibilité des réseaux internes à la structure;
c) adoption de la densité de points d'impact au sol de la foudre NSG en remplacement de la densité des coups de foudre NG dans l'évaluation du nombre moyen annuel d'événements dangereux prévisibles;
d) la réduction de quelques composantes de risque peut être obtenue par l'utilisation de mesures préventives temporaires activées par un système d'alerte aux orages (TWS) conforme à l'IEC 62793. Le risque que des personnes soient directement frappées par la foudre dans des espaces ouverts a été décrit, en tenant compte de la réduction de ce risque au moyen d'un TWS.
Le contenu du corrigendum 1 (2024-10) a été pris en considération dans cet exemplaire.
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Standards Content (Sample)
IEC 62305-2 ®
Edition 3.0 2024-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Évaluation des risques
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IEC 62305-2 ®
Edition 3.0 2024-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Évaluation des risques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.020, 91.120.40 ISBN 978-2-8322-9549-6
– 2 – IEC 62305-2:2024 © IEC 2024
CONTENTS
FOREWORD . 8
INTRODUCTION . 11
1 Scope . 13
2 Normative references . 13
3 Terms and definitions . 13
4 Symbols and abbreviated terms . 21
5 Damage and loss . 25
5.1 Source of damage . 25
5.2 Cause of damage . 25
5.3 Type of loss . 25
6 Risk and risk components . 26
6.1 Risk . 26
6.2 Risk components . 27
6.2.1 Risk components for a structure due to source S1 . 27
6.2.2 Risk component for a structure due to source S2 . 28
6.2.3 Risk components for a structure due to source S3 . 28
6.2.4 Risk component for a structure due to source S4 . 28
6.2.5 Factors affecting risk components for a structure . 28
6.3 Composition of risk components . 29
6.3.1 Composition of risk components according to source of damage . 29
6.3.2 Composition of risk components according to type of loss . 30
7 Risk assessment . 31
7.1 Basic procedure . 31
7.2 Structure to be considered for risk assessment . 31
7.3 Procedure to evaluate the need of protection for risk R . 31
8 Assessment of risk components . 33
8.1 Basic equation . 33
8.2 Assessment of risk components due to different sources of damage . 34
8.3 Partitioning of a structure in risk zones Z . 36
S
8.4 Partitioning of a line into sections S . 37
L
8.5 Assessment of risk components in a zone of a structure with risk zones Z . 38
S
8.5.1 General criteria . 38
8.5.2 Single-zoned structure . 38
8.5.3 Multi-zoned structure . 38
9 Frequency of damage and its components . 39
9.1 Frequency of damage . 39
9.2 Assessment of partial frequency of damage . 39
9.3 Procedure to evaluate the need of protection for frequency of damage F . 40
9.4 Assessment of partial frequency of damage in zones . 42
9.4.1 General criteria . 42
9.4.2 Single-zoned structure . 42
9.4.3 Multi-zoned structure . 42
Annex A (informative) Assessment of annual number N of dangerous events . 43
A.1 General . 43
A.2 Assessment of the average annual number of dangerous events N due to
D
flashes to a structure and N to an adjacent structure . 44
DJ
A.2.1 Determination of the collection area A . 44
D
A.2.2 Structure as a part of a building . 46
A.2.3 Relative location of the structure . 48
A.2.4 Number of dangerous events N for the structure . 48
D
A.2.5 Number of dangerous events N for an adjacent structure . 49
DJ
A.3 Assessment of the average annual number of dangerous events N due to
M
flashes near a structure . 49
A.4 Assessment of the average annual number of dangerous events N due to
L
flashes to a line . 50
A.5 Assessment of average annual number of dangerous events N due to
I
flashes near a line . 51
A.6 Representation of the equivalent collection areas . 52
Annex B (informative) Assessment of probability P of damage . 53
X
B.1 General . 53
B.2 Probability P that a flash to a structure will cause dangerous touch and
AT
step voltages . 54
B.3 Probability P that a flash will cause damage to an exposed person on the
AD
structure . 55
B.4 Probability P that a flash to a structure will cause physical damage by fire
B
or explosion . 57
B.5 Probability P that a flash to a structure will cause failure of internal
C
systems . 59
B.6 Probability P that a flash near a structure will cause failure of internal
M
systems . 63
B.7 Probability P that a flash to a line will cause damage due to touch voltage . 65
U
B.8 Probability P that a flash to a line will cause physical damage by fire or
V
explosion . 67
B.9 Probability P that a flash to a line will cause failure of internal systems . 68
W
B.10 Probability P that a lightning flash near an incoming line will cause failure
Z
of internal systems . 69
B.11 Probability P that a person will be in a dangerous place . 69
P
B.12 Probability P that an equipment will be exposed to a damaging event . 70
e
Annex C (informative) Assessment of loss L . 71
X
C.1 General . 71
C.2 Mean rel
...
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