IEC 62305-4:2010

IEC 62305-4 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
Protection against lightning –
Part 4: Electrical and electronic systems within structures

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IEC 62305-4 ®
Edition 2.0 2010-12
INTERNATIONAL
STANDARD
Protection against lightning –
Part 4: Electrical and electronic systems within structures

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.020; 91.120.40 ISBN 978-2-88912-283-7
– 2 – 62305-4 Ó IEC:2010(E)
CONTENTS
FOREW ORD . 5
INTRODUCTION . 7
1 Sc o pe . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Design and installation of SPM. 13
4.1 General . 13
4.2 Design of SPM . 16
4.3 Lightning protection zones (LPZ) . 17
4.4 Basic SPM . 20
5 Earthing and bonding . 21
5.1 General . 21
5.2 Earth-termination system . 22
5.3 Bonding network . 24
5.4 Bonding bars . 28
5.5 Bonding at the boundary of an LPZ . 29
5.6 Material and dimensions of bonding components . 29
6 Magnetic shielding and line routing . 30
6.1 Spatial shielding . 30
6.2 Shielding of internal lines . 30
6.3 Routing of internal lines . 30
6.4 Shielding of external lines . 31
6.5 Material and dimensions of magnetic shields . 31
7 Coordinated SPD system . 31
8 Isolating interfaces . 32
9 SPM management . 32
9.1 General . 32
9.2 SPM management plan . 32
9.3 Inspection of SPM . 33
9.3.1 Inspection procedure . 34
9.3.2 Inspection documentation . 34
9.4 Maintenance . 35
Annex A (informative) Basis of electromagnetic environment evaluation in an LPZ . 36
Annex B (informative) Implementation of SPM for an existing structure . 60
Annex C (informative) Selection and installation of a coordinated SPD system . 76
Annex D (informative) Factors to be considered in the selection of SPDs . 82
Bibliography . 87

Figure 1 – General principle for the division into different LPZ . 13
Figure 2 – Examples of possible SPM (LEMP protection measures) . 15
Figure 3 – Examples for interconnected LPZ . 19
Figure 4 – Examples for extended lightning protection zones . 20
Figure 5 – Example of a three-dimensional earthing system consisting of the bonding
network interconnected with the earth-termination system . 22
Figure 6 – Meshed earth-termination system of a plant . 23

62305-4 Ó IEC:2010(E) – 3 –
Figure 7 – Utilization of reinforcing rods of a structure for equipotential bonding . 25
Figure 8 – Equipotential bonding in a structure with steel reinforcement . 26
Figure 9 – Integration of conductive parts of internal systems into the bonding network . 27
Figure 10 – Combinations of integration methods of conductive parts of internal
systems into the bonding network . 28
Figure A.1 – LEMP situation due to lightning strike . 37
Figure A.2 – Simulation of the rise of magnetic field by damped oscillations . 40
Figure A.3 – Large volume shield built by metal reinforcement and metal frames . 41
Figure A.4 – Volume for electrical and electronic systems inside an inner LPZ n . 42
Figure A.5 – Reducing induction effects by line routing and shielding measures . 43
Figure A.6 – Example of SPM for an office building . 45
Figure A.7 – Evaluation of the magnetic field values in case of a direct lightning strike . 46
Figure A.8 – Evaluation of the magnetic field values in case of a nearby lightning strike . 48
Figure A.9 – Distance s depending on rolling sphere radius and structure dimensions . 50
a
Figure A.10 – Types of grid-like large volume shields . 52
Figure A.11 – Magnetic field strength H inside a grid-like shield type 1 . 53
1/MAX
Figure A.12 – Magnetic field strength H inside a grid-like shield type 1 according
1/MAX
to mesh width. 53
Figure A.13 – Low-level test to evaluate the magnetic field inside a shielded structure . 55
Figure A.14 – Voltages and currents induced into a loop formed by lines . 56
Figure B.1 – SPM design steps for an existing structure . 63
Figure B.2 – Possibilities to establish LPZs in existing structures . 67
Figure B.3 – Reduction of loop area using shielded cables close to a metal plate . 69
Figure B.4 – Example of a metal plate for additional shielding . 70
Figure B.5 – Protection of aerials and other external equipment . 71
Figure B.6 – Inherent shielding provided by bonded ladders and pipes . 72
Figure B.7 – Ideal positions for lines on a mast (cross-section of steel lattice mast) . 72
Figure B.8 – Upgrading of the SPM in existing structures. 74
Figure C.1 – Surge voltage between live conductor and bonding bar . 79
Figure D.1 – Installation example of test Class I, Class II and Class III SPDs . 83
Figure D.2 – Basic example for different sources of damage to a structure and lightning
current distribution within a system. 84
Figure D.3 – Basic example of balanced current distribution . 85

Table 1 – Minimum cross-sections for bonding components . 30
Table 2 – SPM management plan for new buildings and for extensive changes in
construction or use of buildings . 33
Table A.1 – Parameters relevant to source of harm and equipment . 38
Table A.2 – Examples for I = 100 kA and w = 2 m . 48
0/MAX m
Table A.3 – Magnetic attenuation of grid-like spatial shields for a plane wave . 49
Table A.4 – Rolling sphere radius corresponding to maximum lightning current . 51
Table A.5 – Examples for I = 100 kA and w = 2 m corresponding to SF = 12,6 dB . 51
0/MAX m
Table B.1 – Structural characteristics and surroundings . 60
Table B.2 – Installation characteristics . 61
Table B.3 – Equipment characteristics . 61

– 4 – 62305-4 Ó IEC:2010(E)
Table B.4 – Other questions to be considered for the protection concept . 61
Table D.1 – Preferred values of I . 82
imp
62305-4 Ó IEC:2010(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROTECTION AGAINST LIGHTNING –

Part 4: Electrical and electronic systems within structures

FOREWORD
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