IEC 62305-1:2010

IEC 62305-1 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
Protection against lightning –
Part 1: General principles
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IEC 62305-1 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
Protection against lightning –
Part 1: General principles
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
ICS 29.020; 91.120.40 ISBN 978-2-88912-280-6
– 2 – 62305-1 Ó IEC:2010(E)
CONTENTS
FOREW ORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normativ e 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
5.1.1 Effects of lightning on a structure . 14
5.1.2 Sources and types of damage to a structure . 16
5.2 Types of loss . 16
6 Need and economic justification for lightning protection . 18
6.1 Need for lightning protection . 18
6.2 Economic justification of lightning protection . 19
7 Protection measures. 19
7.1 General . 19
7.2 Protection measures to reduce injury of living beings by electric shock . 19
7.3 Protection measures to reduce physical damage . 20
7.4 Protection measures to reduce failure of electrical and electronic systems . 20
7.5 Protection measures selection . 20
8 Basic criteria for protection of structures. 21
8.1 General . 21
8.2 Lightning protection levels (LPL) . 21
8.3 Lightning protection zones (LPZ) . 23
8.4 Protection of structures . 25
8.4.1 Protection to reduce physical damage and life hazard . 25
8.4.2 Protection to reduce the failure of internal systems . 26
Annex A (informative) Parameters of lightning current . 27
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
com ponents . 48
Annex E (informative) Surges due to lightning at different installation points . 62
Bibliography . 67

Figure 1 – Connection between the various parts of IEC 62305 . 7
Figure 2 – Types of loss and corresponding risks resulting from different types of
dam age . 18
Figure 3 – LPZ defined by an LPS (IEC 62305-3) . 24
Figure 4 – LPZ defined by an SPM (IEC 62305-4) . 25
Figure A.1 – Definitions of impulse current parameters (typically T � 2 ms) . 27
Figure A.2 – Definitions of long duration stroke parameters (typically 2 ms �T
LONG
�1 s) . 28

62305-1 Ó IEC:2010(E) – 3 –
Figure A.3 – Possible components of downward flashes (typical in flat territory and
to lower structures) . 28
Figure A.4 – Possible components of upward flashes (typical to exposed and/or
higher structures) . 29
Figure A.5 – Cumulative frequency distribution of lightning current parameters (lines
through 95 % and 5 % value) . 34
Figure B.1 – Shape of the current rise of the first positive impulse . 39
Figure B.2 – Shape of the current tail of the first positive impulse . 40
Figure B.3 – Shape of the current rise of the first negative impulse . 40
Figure B.4 – Shape of the current tail of the first negative impulse . 41
Figure B.5 – Shape of the current rise of the subsequent negative impulses . 42
Figure B.6 – Shape of the current tail of the subsequent negative impulses . 42
Figure B.7 – 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 positive impulse and the charge of the long stroke . 45
Figure C.2 – Definition of 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 positive impulse for large test items . 47
Figure C.4 – Example test generator for the simulation of the front steepness of the
subsequent negative impulses for large test items . 47
Figure D.1 – General arrangement of two conductors for the calculation of
electrodynamic force . 54
Figure D.2 – Typical conductor arrangement in an LPS. 55
Figure D.3 – Diagram of the stresses F for the configuration of Figure D.2. 55
Figure D.4 – Force per unit length F’ along the horizontal conductor of Figure D.2 . 56

Table 1 – Effects of lightning on typical structures . 15
Table 2 – Damage and loss relevant to a structure according to different points of
strike of lightning . 17
Table 3 – Maximum values of lightning parameters according to LPL . 22
Table 4 – Minimum values of lightning parameters and related rolling sphere radius
corresponding to LPL . 22
Table 5 – Probabilities for the limits of the lightning current parameters . 23
Table A.1 – Tabulated values of lightning current parameters taken from CIGRE
[3], [4]
(Electra No. 41 or No. 69) . 31
Table A.2 – Logarithmic normal distribution of lightning current parameters – Mean
m and dispersion σ calculated from 95 % and 5 % values from CIGRE (Electra No.
log
[3], [4]
41 or No. 69) . 32
Table A.3 – Values of probability P as function of the lightning current I . 33
Table B.1 – Parameters for Equation (B.1). 38
Table C.1 – Test parameters of the first positive impulse . 45
Table C.2 – Test parameters of the long stroke . 45
Table C.3 – Test parameters of the impulses . 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

– 4 – 62305-1 Ó IEC:2010(E)
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 . 63
Table E.2 – Expected surge overcurrents due to lightning flashes on low-voltage
system s . 64
Table E.3 – Expected surge overcurrents due to lightning flashes on
telecommunication systems . 65

62305-1 Ó IEC:2010(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROTECTION AGAINST LIGHTNING –

Part 1: General principles
FOREWORD
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