IEC 62305-4:2024

IEC 62305-4 ®
Edition 3.0 2024-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 4: Electrical and electronic systems within structures

Protection contre la foudre –
Partie 4: Réseaux de puissance et de communication dans les structures
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IEC 62305-4 ®
Edition 3.0 2024-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –

Part 4: Electrical and electronic systems within structures

Protection contre la foudre –
Partie 4: Réseaux de puissance et de communication dans les structures

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.020, 91.120.40 ISBN 978-2-8322-7933-5

– 2 – IEC 62305-4:2024 © IEC 2024
CONTENTS
FOREWORD . 8
INTRODUCTION . 10
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 12
4 Design and installation of SPM . 16
4.1 General . 16
4.2 Design of SPM . 20
4.3 Lightning protection zones (LPZs) . 20
4.3.1 General . 20
4.3.2 Outer zones . 20
4.3.3 Inner zones . 21
4.4 Basic SPM . 23
5 Earthing and bonding networks . 24
5.1 General . 24
5.2 Earth-termination system . 25
5.3 Bonding network . 26
5.4 Bonding bars . 31
5.5 Bonding at the boundary of an LPZ . 32
5.6 Material and dimensions of bonding components . 32
6 Magnetic shielding and line routing . 33
6.1 General . 33
6.2 Spatial shielding . 33
6.3 Shielding of internal lines . 33
6.4 Routing of internal lines . 34
6.5 Shielding of external lines . 34
6.6 Material and dimensions of magnetic shields . 34
7 Coordinated SPD system . 34
8 Isolating interfaces . 35
9 SPM management . 35
9.1 General . 35
9.2 SPM management plan . 36
9.3 Inspection of SPM . 38
9.3.1 General . 38
9.3.2 Inspection procedure . 38
9.3.3 Inspection documentation . 39
9.4 Maintenance . 39
Annex A (informative) Basis of electromagnetic environment evaluation in an LPZ . 40
A.1 General . 40
A.2 Damaging effects on electrical and electronic systems due to lightning . 40
A.2.1 Sources of damage . 40
A.2.2 Object of damage . 40
A.2.3 Withstand of equipment signal ports . 40
A.2.4 Withstand of equipment power ports . 41
A.2.5 Relationship between the object of damage and the source of damage . 42
A.3 Spatial shielding, line routing and line shielding . 42

A.3.1 General . 42
A.3.2 Grid-like spatial shields . 45
A.3.3 Line routing and line shielding . 47
A.4 Magnetic field inside LPZ . 51
A.4.1 Approximation for the magnetic field inside LPZ . 51
A.4.2 Numerical magnetic field calculation in case of direct lightning strikes . 57
A.4.3 Experimental evaluation of the magnetic field due to a direct lightning
strike . 61
A.5 Calculation of induced voltages and currents . 62
A.5.1 General . 62
A.5.2 Situation inside LPZ 1 in the case of a direct lightning strike . 62
A.5.3 Situation inside LPZ 1 in the case of a nearby lightning strike . 65
A.5.4 Situation inside LPZ 2 and higher . 66
Annex B (informative) Implementation of SPM for an existing structure . 67
B.1 General . 67
B.2 Checklists . 67
B.3 Design of SPM for an existing structure . 68
B.4 Design of basic protection measures for LPZs . 70
B.4.1 Design of basic protection measures for LPZ 1 . 70
B.4.2 Design of basic protection measures for LPZ 2 . 70
B.4.3 Design of basic protection measures for LPZ 3 . 71
B.5 Improvement of an existing LPS using spatial shielding of LPZ 1 . 71
B.6 Establishment of LPZs for electrical and electronic systems . 71
B.7 Protection using a bonding network . 74
B.8 Protection by surge protective devices . 74
B.9 Protection by isolating interfaces . 75
B.10 Protection measures by line routing and shielding . 75
B.11 Protection measures for externally installed equipment . 77
B.11.1 General .
...