---

Figure E.9 - Connection of the continuous strip windows to a metal facade covering 78

Figure E.10 - Internal down-conductors in industrial structures 81

Figure E.11 - Installation of bonding conductors in reinforced concrete structures and flexible bonds between two reinforced concrete parts 83

Figure E.12 - Protection angle method air-termination design for different heights according to Table 2 87

Figure E.13 - Isolated external LPS using two isolated air-termination masts designed according to the protection angle air-termination design method 88

Figure E.14 - Isolated external LPS using two isolated air-termination masts, interconnected by horizontal catenary wire 89

Figure E.15 - Example of design of an air-termination of a non-isolated LPS by air­termination rods 90

Figure E.16 - Example of design of an air-termination of a non isolated LPS by a horizontal wire according to the protection angle air-termination design method 91

Figure E.17 - Protected volume of an air- termination rod on a sloped surface using the protection angle design method 92

Figure E.18 - Design of an LPS air-termination conductor network on a structure with complicated shape 93

Figure E.19 - Design of an LPS air-termination according to the protection angle method, mesh method and general arrangement of air-termination elements 94

Figure E.20 - Space protected by two parallel air-termination horizontal wires or two air-termination rods (r> h_t) 95

Figure E.21 - Three examples of design of non-isolated LPS air-termination according to the mesh method air-termination design 98

Figure E.22 - Four examples of details of an LPS on a structure with sloped tiled roofs 100

Figure E.23 - Air-termination and visually concealed conductors for buildings less than 20 m high, with sloping roofs 101

Figure E.24 - Construction of an LPS using natural components on the roof of the structure 103

Figure E.25 - Positioning of the external LPS on a structure made of isolating material e.g. wood or bricks with a height up to 60 m with flat roof and with roof fixtures 104

Figure E.26 - Construction of air-termination network on a roof with conductive covering where puncturing of the covering is not acceptable 105

Figure E.27 - Construction of external LPS on a structure of steel-reinforced concrete using the reinforcement of the outer walls as natural components 106

Figure E.28 - Example of an air-termination stud used on car park roofs 107

Figure E.29 - Air-termination rod used for protection of a metallic roof fixture with electric power installations which are not bonded to the air-termination system 108

Figure E.30 - Method of achieving electrical continuity on metallic parapet capping 109

Figure E.31 - Metallic roof fixture protected against direct lightning interception, connected to air-termination system 112

Figure Е.32 - Examplesof lightning protection of a house with a TV antenna 115

Figure E.33 - Installation of lightning protection of metallic equipment on a roof against a direct lightning flash 116

Figure E.34 - Connection of natural air-termination rod to air-termination conductor 118

Figure E.35 - Construction of the bridging between the segments of the metallic facade plates 119

Figure E.36 - Installation of external LPS on a structure of insulating material with different roof levels 122

Figure E.37 - Five examples of geometry of LPS conductors 123

Figure E.38 - Construction of an LPS using only two down-conductors and foundation earth electrodes 124

Figure E.39 - Four examples of connection of earth-termination to the LPS of structures using natural down-conductors (girders) and detail of a test joint 128

Figure E.40 - Construction of foundation earth ring for structures of different foundation design 132

Figure E.41 - Two examples of vertical electrodes in type A earthing arrangement 134

Figure E.42 - Meshed earth-termination system of a plant 137

Figure E.43 - Example of an equipotential bonding arrangement 144

Figure E.44 - Example of bonding arrangement in a structure with multiple point

entries of external conductive parts using a ring electrode for interconnection of bonding bars 145

Figure E.45 - Example of bonding in the case of multiple point entries of external conductive parts and an electric power or communication line using an internal ring conductor for interconnection of the bonding bars 146

Figure E.46 - Example of bonding arrangement in a structure with multiple point entries of external conductive parts entering the structure above ground level 147

Figure E.47 - Directions for calculations of the separation distance, s, for a worst case lightning interception point at a distance I from the reference point according to 6.3 149

Table 1 - Relation between lightning protection levels (LPL) and class of LPS (see IEC 62305-1) 16

2. - Maximum values of rolling sphere radius, mesh size and protection angle corresponding to the class of LPS 19

3. - Minimum thickness of metal sheets or metal pipes in air-termination systems 21

4. - Typical preferred values of the distance between down-conductors according to the class of LPS 22

5. - LPS materials and conditions of use 28

6. - Material, configuration and minimum cross-sectional area of air-termination conductors, air-termination rods, earth lead-in rods and down-conductors 30

7. - Material, configuration and minimum dimensions of earth electrodes 31

8. - Minimum dimensions of conductors connecting different bonding bars or connecting bonding bars to the earth-termination system 33

9. - Minimum dimensions of conductors connecting internal metal installations to the bonding bar 33

10. - Isolation of external LPS - Values of coefficient k_t 35

11. - Isolation of external LPS - Values of coefficient k_m 35

12. - Isolation of external LPS - Approximated values of coefficient k_c 36

Table B.1 - Cable length to be considered according to the condition of the screen 45

Table E.1 - Suggested fixing centres 99

T

151

able Е.2 - Maximum period between inspections of an LPSINTERNATIONAL ELECTROTECHNICAL COMMISSION

PROTECTION AGAINST LIGHTNING -

Part 3: Physical damage to structures and life hazard

FOREWORD

1. The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non­governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

2. The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.

3. IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user.

4. In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

5. IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies.

6. All users should ensure that they have the latest edition of this publication.

7. No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.

8. Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication.

9. Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 62305-3 has been prepared by IEC technical committee 81: Lightning protection.

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. Minimum thicknesses of metal sheets or metal pipes given in Table 3 for air-termination systems are assumed as not able to prevent hot-spot problems.

2. Steel with electro-deposited copper is introduced as material suitable for LPS.

3. Some cross-sectional areas of LPS conductors were slightly modified.

4. For bonding purposes, isolating spark gaps are used for metal installations and SPD for internal systems.

5. Two methods - simplified and detailed - are provided for evaluation of separation distance.

6. Protection measures against injuries of living beings due to electric shock are considered also inside the structure.

7. Improved information for LPS in the case of structures with a risk of explosion are given in Annex D (normative).

The text of this standard is based on the following documents:

Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table.

This publication has been drafted, as closely as possible, in accordance with the ISO/IEC Directives, Part 2.

A list of all the parts in the IEC 62305 series, under the general title Protection against lightning, can be found on the IEC website.The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be

• reconfirmed,

• withdrawn,

• replaced by a revised edition, or

• amended.

In the United States, based on the requirements of NFPA 780: Standard for the Installation of Lightning Protection Systems:2008 1 and practical experience in the use of horizontal earth electrodes, the minimum length of horizontal earth electrodes is not required to be twice that required for vertical electrodes.

In France and Portugal:

• natural components cannot substitute as lightning protection components but may be used to complete/enhance the LPS;

• aluminium solid round diameters should be increased from 8 mm to 10 mm;

• stranded conductors cannot be used as down-conductors;

• diameter of solid round conductors should be increased from 16 mm to 18 mm;

• hot dip galvanized steel solid tape thickness should be increased from 2 mm to 3,5 mm.

In Russia the use of piping carrying and tanks containing readily-combustible or explosive materials as air­termination natural components or down-conductor natural components are not allowed in any case.

In Japan the minimum values of the cross-section are reduced from:

• 16 mm² to 14 mm² for copper and 25 mm² to 22 mm² for aluminium, for bonding conductors connecting different bonding bars and conductors connecting the bars to the earth-termination system;

• 6 mm² to 5 mm² for copper, 10 mm² to 8 mm² for aluminium and 16 mm² to 14 mm² for steel, for bonding conductors connecting internal metal installations to the bonding bars.

A bilingual version of this publication may be issued at a later date.

IMPORTANT - The 'colour inside' logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. ³

INTRODUCTION

This part of IEC 62305 deals with the protection, in and around a structure, against physical damage and injury to living beings due to touch and step voltages.

The main and most effective measure for protection of structures against physical damage is considered to be the lightning protection system (LPS). It usually consists of both external and internal lightning protection systems.

An external LPS is intended to

1. intercept a lightning flash to the structure (with an air-termination system),

2. conduct the lightning current safely towards earth (using a down-conductor system),

3. disperse the lightning current into the earth (using an earth-termination system).

An internal LPS prevents dangerous sparking within the structure using either equipotential bonding or a separation distance (and hence electrical insulation) between the external LPS (as defined in 3.2) components and other electrically conducting elements internal to the structure.

Main protection measures against injury to living beings due to touch and step voltages are intended to:

1. reduce the dangerous current flowing through bodies by insulating exposed conductive parts, and/or by increasing the surface soil resistivity,

2. reduce the occurrence of dangerous touch and step voltages by physical restrictions and/or warning notices.

The type and location of an LPS should be carefully considered in the initial design of a new structure, thereby enabling maximum advantage to be taken of the electrically conductive parts of the structure. By doing so, design and construction of an integrated installation is made easier, the overall aesthetic aspects can be improved, and the effectiveness of the LPS can be increased at minimum cost and effort.

Access to the ground and the proper use of foundation steelwork for the purpose of forming an effective earth-termination may well be impossible once construction work on a site has commenced. Therefore, soil resistivity and the nature of the earth should be considered at the earliest possible stage of a project. This information is fundamental to the design of an earth­termination system and may influence the foundation design work for the structure.

Regular consultation between LPS designers and installers, architects and builders is essential in order to achieve the best result at minimum cost.

If lightning protection is to be added to an existing structure, every effort should be made to ensure that it conforms to the principles of this standard. The design of the type and location of an LPS should take into account the features of the existing structure.

PROTECTION AGAINST LIGHTNING -

Part 3: Physical damage to structures and life hazard

1. Scope

This part of IEC 62305 provides the requirements for protection of a structure against physical damage by means of a lightning protection system (LPS), and for protection against injury to living beings due to touch and step voltages in the vicinity of an LPS (see IEC 62305-1).

This standard is applicable to:

1. design, installation, inspection and maintenance of an LPS for structures without limitation of their height,

2. establishment of measures for protection against injury to living beings due to touch and step voltages.

NOTE 1 Specific requirements for an LPS in structures dangerous to their surroundings due to the risk of explosion are under consideration. Additional information is provided in Annex D for use in the interim.

NOTE 2 This part of IEC 62305 is not intended to provide protection against failures of electrical and electronic systems due to overvoltages. Specific requirements for such cases are provided in IEC 62305-4.

NOTE 3 Specific requirements for protection against lightning of wind turbines are reported in IEC 61400-24 ^{1 J}.

2. Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

IEC 60079-10-1:2008, Explosive atmospheres - Part 10-1: Classification of areas - Explosive gas atmospheres

IEC 60079-10-2:2009, Explosive atmospheres - Part 10-2: Classification of areas - Combustible dust atmospheres

IEC 60079-14:2007, Explosive atmospheres - Part 14: Electrical installations design, selection and erection

IEC 61557-4, Electrical safety in low-voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 4: Resistance of earth connection and equipotential bonding

IEC 61643-1, Low-voltage surge protective devices - Part 1: Surge protective devices connected to low-voltage power distribution systems - Requirements and tests

IEC 61643-21, Low-voltage surge protective devices - Part 21: Surge protective devices connected to telecommunications and signalling networks - Performance requirements and testing methods

IEC 62305-1, Protection against lightning - Part 1: General principles

IEC 62305-2, Protection against lightning - Part 2: Risk management

I EC 62305-4, Protection against lightning - Part 4: Electrical and electronic systems within structures

2 _y

I EC 62561 (all parts) , Lightning protection system components (LPSC)

IEC 62561-1⁴, Lightning protection system components (LPSC) - Part 1: Requirements for connection components

IEC 62561-3³, Lightning protection system components (LPSC) - Part 3: Requirements for isolating spark gaps

ISO 3864-1, Graphical symbols - Safety colours and safety signs - Part 1: Design principles for safety signs in workplaces and public areas

3 Terms and definitions

For the purposes of this document, the following terms and definitions, some of which have already been cited in Part 1 but are repeated here for ease of reference, as well as those given in other parts of IEC 62305, apply.

lightning protection system

LPS

complete system used to reduce physical damage due to lightning flashes to a structure

NOTE It consists of both external and internal lightning protection systems.

external lightning protection system

part of the LPS consisting of an air-termination system, a down-conductor system and an earth-termination system

external LPS isolated from the structure to be protected

LPS with an air-termination system and down-conductor system positioned in such a way that the path of the lightning current has no contact with the structure to be protected

NOTE In an isolated LPS, dangerous sparks between the LPS and the structure are avoided.

external LPS not isolated from the structure to be protected

LPS with an air-termination system and down-conductor system positioned in such a way that the path of the lightning current can be in contact with the structure to be protected

internal lightning protection system

part of the LPS consisting of lightning equipotential bonding and/or electrical insulation of external LPS

air-termination system

7. part of an external LPS using metallic elements such as rods, mesh conductors or catenary wires intended to intercept lightning flashes

down-conductor system

part of an external LPS intended to conduct lightning current between the air-termination system and the earth-termination system

ring conductor

conductor forming a loop around the structure and interconnecting the down-conductors for distribution of lightning current among them

earth-termination system

part of an external LPS which is intended to conduct and disperse lightning current into the earth

3.10

earth electrode

part or a group of parts of the earth-termination system which provides direct electrical contact with the earth and disperses lightning current to the earth

3.11

ring earth electrode

earth electrode forming a closed loop around the structure below or on the surface of the earth

3.12

foundation earth electrode

conductive part buried in the soil under a building foundation or, preferably, embedded in concrete of a building foundation, generally in form of a closed loop

[IEC 60050-826:2004, 826-13-08] ^[3]

3.13

conventional earth impedance

ratio of the peak values of the earth-termination voltage and the earth-termination current which, in general, do not occur simultaneously

3.14

earth-termination voltage

potential difference between the earth-termination system and the remote earth

3.15

natural component of LPS

conductive component installed not specifically for lightning protection which can be used in addition to the LPS or in some cases could provide the function of one or more parts of the LPS

NOTE Examples of the use of this term include:

• natural air-termination;

• natural down-conductor;

• natural earth electrode.

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