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  • AS 1768-1991

    Superseded A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.
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    Lightning protection

    Available format(s):  Hardcopy, PDF 1 User, PDF 3 Users, PDF 5 Users, PDF 9 Users

    Superseded date:  30-06-2017

    Language(s):  English

    Published date:  09-12-1991

    Publisher:  Standards Australia

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    Table of Contents - (Show below) - (Hide below)

    1 - AS/NZS 1768-1991 LIGHTNING PROTECTION
    4 - PREFACE
    5 - CONTENTS
    7 - SECTION 1 SCOPE AND GENERAL
    7 - 1.1 SCOPE
    7 - 1.2 APPLICATION
    7 - 1.3 REFERENCED DOCUMENTS
    7 - 1.4 DEFINITIONS
    7 - 1.4.1 Air termination
    7 - 1.4.2 Air termination network
    7 - 1.4.3 Base conductors (base tapes)
    7 - 1.4.4 Bond (bonding conductor)
    7 - 1.4.5 Downconductor
    7 - 1.4.6 Earth impedance (Z)
    7 - 1.4.7 Earth potential rise (EPR)
    7 - 1.4.8 Earthing boss (terminal lug)
    7 - 1.4.9 Earthing conductor
    8 - 1.4.10 Earthing electrodes (earth rods or ground rods)
    8 - 1.4.11 Earthing resistance
    8 - 1.4.12 Earth termination (earth termination network)
    8 - 1.4.13 Explosive gas atmosphere
    8 - 1.4.14 Finial
    8 - 1.4.15 Hazardous area
    8 - 1.4.16 Joint
    8 - 1.4.17 Lightning flash (lightning discharge)
    8 - 1.4.18 Lightning flash density
    8 - 1.4.19 Lightning protection system
    8 - 1.4.20 Lightning strike
    8 - 1.4.21 Lightning strike attachment point
    8 - 1.4.22 Lightning stroke
    8 - 1.4.23 Side flash
    8 - 1.4.24 Striking distance (ds)
    8 - 1.4.25 Structure or object
    8 - 1.4.26 Surge arrestor
    8 - 1.4.27 Test link
    8 - 1.4.28 Thunderday
    8 - 1.4.29 Zone of protection
    9 - SECTION 2 ANALYSIS OF NEED FOR PROTECTION
    9 - 2.1 NEED FOR PERSONAL PROTECTION
    9 - 2.2 NEED FOR PROTECTION OF BUILDINGS AND CONTENTS
    9 - 2.2.1 Factors governing decision whether or not to protect
    9 - 2.2.2 Risk index
    10 - 2.2.3 Value and nature of building and contents
    10 - 2.2.4 Relative exposure
    10 - 2.2.5 Frequency and severity of thunderstorms
    10 - 2.3 NEED FOR PROTECTION OF PERSONS AND EQUIPMENT WITHIN BUILDINGS
    15 - SECTION 3 BEHAVIOURAL PRECAUTIONS FOR PERSONAL SAFETY
    15 - 3.1 SCOPE OF SECTION
    15 - 3.2 PERSONAL CONDUCT
    15 - 3.3 EFFECT ON PERSONS AND TREATMENT FOR INJURY BY LIGHTNING*
    16 - SECTION 4 PROTECTION OF BUILDINGS
    16 - 4.1 SCOPE OF SECTION
    16 - 4.2 ZONES OF PROTECTION
    16 - 4.2.1 Basis of recommendations
    16 - 4.2.2 Required protection
    16 - 4.3 METHODS OF PROTECTION
    16 - 4.3.1 Structural steel-framed buildings
    19 - 4.3.2 Buildings without structural steel frames
    20 - 4.3.3 Structures with flammable or explosive atmosphere
    20 - 4.4 MATTERS TO BE CONSIDERED WHEN PLANNING PROTECTION
    20 - 4.4.1 Structures to be erected
    20 - 4.4.2 Design considerations
    23 - 4.5 MATERIALS
    23 - 4.5.1 General
    23 - 4.5.2 Corrosion
    25 - 4.6 FORM AND SIZE OF CONDUCTORS
    25 - 4.6.1 Factors influencing selection
    25 - 4.6.2 Electrical and thermal considerations
    25 - 4.6.3 Mechanical strength and corrosion considerations
    26 - 4.7 JOINTS
    26 - 4.7.1 Effectiveness of joints
    26 - 4.7.2 Protective covering
    26 - 4.8 FASTENERS
    26 - 4.9 AIR TERMINATIONS
    26 - 4.9.1 General requirements
    27 - 4.9.2 Protection of roofs
    27 - 4.9.3 Protection of the sides of tall buildings
    28 - 4.10 DOWNCONDUCTORS
    28 - 4.10.1 Structures- General
    28 - 4.10.2 Route
    29 - 4.10.3 Mechanical damage
    29 - 4.11 TEST LINKS
    29 - 4.12 EARTH TERMINATIONS
    29 - 4.12.1 General principles
    29 - 4.12.2 Resistance to earth
    31 - 4.12.3 Common earthing electrode and potential equalization
    31 - 4.13 EARTHING ELECTRODES
    31 - 4.13.1 General considerations
    31 - 4.13.2 Connections to electrodes
    32 - 4.13.3 Inspection and testing of electrodes
    32 - 4.14 METAL IN AND ON A STRUCTURE
    32 - 4.14.1 Use of metal in or on a structure as a part of the lightning protection system
    32 - 4.14.2 Prevention of side flashing
    35 - SECTION 5 PROTECTION OF PERSONS AND EQUIPMENT WITHIN BUILDINGS
    35 - 5.1 SCOPE OF SECTION
    35 - 5.2 NEED FOR PROTECTION
    35 - 5.3 MODES OF ENTRY OF LIGHTNING IMPULSES
    36 - 5.4 GENERAL CONSIDERATIONS FOR PROTECTION
    38 - 5.5 PROTECTION OF PERSONS WITHIN BUILDINGS
    38 - 5.5.1 Objectives of protection
    38 - 5.5.2 Installation of equipotential bonding
    39 - 5.6 PROTECTION OF EQUIPMENT
    39 - 5.6.1 General
    39 - 5.6.2 Primary protection
    39 - 5.6.3 Secondary protection
    44 - SECTION 6 PROTECTION OF MISCELLANEOUS STRUCTURES AND PROPERTY
    44 - 6.1 SCOPE OF SECTION
    44 - 6.2 STRUCTURES WITH RADIO AND TELEVISION AERIALS
    44 - 6.2.1 Indoor aerial system
    44 - 6.2.2 Outdoor aerials on protected structures
    44 - 6.2.3 Aerials on unprotected structures
    44 - 6.2.4 Earthing of radio systems
    44 - 6.3 STRUCTURES NEAR TREES
    44 - 6.4 PROTECTION OF TREES
    45 - 6.5 CHIMNEYS, METAL GUY-WIRES OR CABLES
    45 - 6.5.1 General
    45 - 6.5.2 Metal ladders and metal linings
    45 - 6.5.3 Reinforced concrete chimneys
    45 - 6.6 PROTECTION OF MINES
    45 - 6.6.1 Factors influencing need for protection
    45 - 6.6.2 Object of recommendations
    45 - 6.6.3 Underground workings
    46 - 6.6.4 Surface workings
    46 - 6.6.5 Lightning detector
    46 - 6.7 PROTECTION OF BOATS
    46 - 6.7.1 General
    46 - 6.7.2 Elements of the protection system
    47 - 6.7.3 Installation recommendations
    47 - 6.7.4 Precautions for persons and maintenance suggestions
    47 - 6.8 FENCES
    48 - 6.9 MISCELLANEOUS STRUCTURES
    48 - 6.9.1 Large tents and marquees
    48 - 6.9.2 Small tents
    48 - 6.9.3 Metal scaffolding and similar structures, including overbridges
    48 - 6.9.4 Tall metal masts, towers, cranes and revolving and travelling structures
    49 - 6.10 PROTECTION OF HOUSES AND SMALL BUILDINGS
    49 - 6.10.1 General considerations
    49 - 6.10.2 Air termination for the building
    49 - 6.10.3 Provision of downconductors for the building
    49 - 6.10.4 Provision of earthing electrodes
    50 - SECTION 7 PROTECTION OF STRUCTURES WITH EXPLOSIVE OR HIGHLY- FLAMMABLE CONTENTS
    50 - 7.1 SCOPE OF SECTION
    50 - 7.2 GENERAL CONSIDERATIONS
    50 - 7.2.1 Acceptable risks
    50 - 7.2.2 Protection required
    50 - 7.2.3 Electrostatic shielding
    50 - 7.3 AREAS OF APPLICATION
    50 - 7.4 EQUIPMENT APPLICATION
    50 - 7.4.1 Earth bosses
    51 - 7.4.2 Bonding conductors
    51 - 7.4.3 Sizes of tapes
    51 - 7.4.4 Downconductors (see Clause 4.10)
    51 - 7.4.5 Air terminations (see Clause 4.9)
    51 - 7.5 SPECIFIC OCCUPANCIES
    51 - 7.5.1 Protection of steel tanks
    53 - 7.5.2 Installations handling crude oil and products
    53 - 7.5.3 Aircraft fuelling and de-fuelling
    53 - 7.5.4 Structures with explosive or highly flammable contents
    55 - SECTION 8 INSTALLATION AND MAINTENANCE PRACTICE
    55 - 8.1 WORK ON SITE
    55 - 8.2 INSPECTION
    55 - 8.3 TESTING
    55 - 8.4 RECORDS
    55 - 8.5 MAINTENANCE
    56 - APPENDIX A - THE NATURE OF LIGHTNING AND THE PRINCIPLES OF LIGHTNING PROTECTION
    56 - A1 SCOPE OF APPENDIX
    56 - A2 THE NATURE OF LIGHTNING
    56 - A2.1 Nature of lightning
    56 - A2.2 The lightning attachment process
    56 - A2.3 Thunderstorm and lightning occurrence
    57 - A3 EFFECTS OF LIGHTNING
    58 - A4 POTENTIAL DIFFERENCES CAUSED BY LIGHTNING
    58 - A4.1 General
    59 - A4.2 Earth currents
    59 - A4.3 Side-flash
    59 - A4.4 Potential (voltage) differences
    59 - A5 PRINCIPLES OF LIGHTNING PROTECTION
    59 - A5.1 Purpose of protection
    59 - A5.2 Interception of lightning
    59 - A5.3 Determination of lightning strike attachment points to buildings
    61 - A5.4 Protection of the sides of tall buildings
    62 - A5.5 Safe discharge to earth
    62 - A5.6 Potential equalization
    62 - A6 ELEMENTS OF A PROTECTION SYSTEM
    63 - A7 VARIATION IN THE LEVEL OF LIGHTNING PROTECTION PROVIDED
    64 - A8 COLLECTION VOLUME DESIGN
    64 - A8.1 Introduction
    64 - A8.2 Basis of design method
    65 - A8.3 Practical application
    65 - A8.4 References
    68 - APPENDIX B - NOTES ON EARTHING ELECTRODES AND MEASUREMENT OF EARTH IMPEDANCE
    68 - B1 GENERAL
    68 - B1.1 Function of earth electrode system
    68 - B1.2 Factors influencing earth impedance
    68 - B1.3 Measures for reducing earth impedance
    68 - B2 RESISTIVITY OF SOIL
    68 - B2.1 General
    70 - B2.2 Artificial reduction of soil resistivity
    70 - B2.3 Determining soil resistivity by test
    70 - B3 CALCULATION OF EARTH RESISTANCE OF AN ELECTRODE
    71 - B4 USE OF ELECTRODES IN PARALLEL
    72 - B5 DRIVEN OR DRILLED ELECTRODES
    72 - B5.1 General
    72 - B5.2 Safety
    72 - B5.3 Installation
    72 - B5.4 Materials for electrodes
    72 - B5.5 Electrode diameter
    72 - B5.6 Depth of installation
    73 - B5.7 Sleeving of exposed part of vertical electrode
    73 - B5.8 Comparison with other electrode types
    73 - B6 BURIED STRIP ELECTRODES
    74 - B7 BURIED PLATE ELECTRODES
    74 - B8 CONCRETE FOOTING ELECTRODES
    74 - B9 INSPECTION AND MAINTENANCE OF ELECTRODES
    75 - B10 MEASUREMENT OF SOIL RESISTIVITY, EARTH ELECTRODE RESISTANCE AND EARTHING SYSTEM IMPEDANCE
    75 - B10.1 Determination of soil resistivity by test
    75 - B10.2 Electrode resistance testing – three-pin method
    77 - B10.3 Isolation of surge impedance of an electrode system from other fortuitous earth paths
    79 - APPENDIX C - THE CALCULATION OF LIGHTNING DISCHARGE VOLTAGES AND REQUISITE SEPARATION DISTANCES FOR ISOLATION OF A LIGHTNING
    79 - C1 GENERAL
    80 - C2 TRANSIENT VOLTAGE CALCULATIONS BY TRAVELLING WAVE ANALYSIS
    80 - C2.1 Simplified travelling wave characteristics
    81 - C2.2 Surge voltage calculation by lattice diagram
    82 - C3 SURGE VOLTAGE CALCULATIONS BY LUMPED CIRCUIT APPROXIMATIONS
    86 - APPENDIX D - WAVESHAPES FOR ASSESSING THE SUSCEPTIBILITY OF EQUIPMENT TO TRANSIENT OVERVOLTAGES DUE TO LIGHTNING
    90 - APPENDIX E - ALTERNATIVE DETERMINATION OF INDEX E BASED ON LIGHTNING FLASH DENSITY/ENERGY DATA
    90 - E1 INTRODUCTION
    90 - E2 DERIVATION OF INDEX E BASED DIRECTLY ON RECORDED LIGHTNING FLASH DENSITY
    90 - E3 DERIVATION OF INDEX E BASED ON RECORDED INCIDENCE OF GROUND FLASHES OF ABOVE-AVERAGE ENERGY.
    91 - E4 LIGHTNING FLASH DENSITY/ENERGY DATA FOR SOUTH EAST QUEENSLAND AND NORTHERN NEW SOUTH WALES
    96 - APPENDIX F - REFERENCED DOCUMENTS

    Abstract - (Show below) - (Hide below)

    Sets out guidelines for the protection of persons and property from hazards arising from exposure to lightning. In particular, it covers: the protection of persons from both direct and indirect effects of a lightning strike; the protection of various buildings and structures from the risk of physical damage or fire; and the protection of sensitive equipment from overvoltages resulting from a lightning strike to a building or its associated services. The nature of lightning and the principles of lightning protection are discussed and guidance is given to assist in determining if a particular building or structure should be protected. Identical with NZS 1768:1991 and produced as a Joint Australian/New Zealand Standard.

    Scope - (Show below) - (Hide below)

    This Standard sets out guidelines for the protection of persons and property from hazards arising from exposure to lightning. The recommendations specifically cover the following applications:(a) The protection of persons, both outdoors, where they may be at risk from the direct effects of a lightning strike, and indoors, where they may be at risk indirectly as a consequence of lightning currents being conducted into the building.(b) The protection of a variety of buildings or structures, including those with explosive or highly-flammable contents, and mines.(c) The protection of sensitive electronic equipment (e.g. facsimile machines, modems, computers) from overvoltages resulting from a lightning strike to the building or its associated services.The nature of lightning and the principles of lightning protection are discussed and guidance is given to assist in a determination of whether protective measures should be taken.The recommendations in this Standard do not apply to the protection of large scale power or communications systems, nor do they apply to the protection of special structures such as oil and gas platforms.

    General Product Information - (Show below) - (Hide below)

    Committee EL-024
    Document Type Standard
    Publisher Standards Australia
    Status Superseded
    Superseded By
    Supersedes
    Under Revision

    History - (Show below) - (Hide below)

    Under Revision see DR 02359 In Australia First published as AS MC1-1969.
    Revised and redesignated AS 1768-1975.
    Second edition 1983.
    Third edition 1991.
    In New Zealand In Australia First published as AS MC1-1969. Revised and redesignated AS 1768-1975. Second edition 1983. Third edition 1991. In New Zealand

    Standards Referenced By This Book - (Show below) - (Hide below)

    AS 2832.1-1985 Guide to the cathodic protection of metals - Pipes, cables and ducts
    AS 1565-1996 Copper and copper alloys - Ingots and castings (Reconfirmed 2020)
    AS 2837-1986 Wrought alloy steels - Stainless steel bars and semi-finished products
    AS 1074-1989 Steel tubes and tubulars for ordinary service (Reconfirmed 2018)
    AS 1866-1986 Aluminium and aluminium alloys - Extruded rod, bar, solid and hollow shapes
    AS 1567-1985 Copper and copper alloys - Wrought rods, bars and sections
    AS 2738.2-1984 Copper and copper alloys - Compositions and designations - Wrought products
    AS 3004-1993 Electrical installations - Marinas and pleasure craft at low voltage
    AS 2239-1993 Galvanic (sacrificial) anodes for cathodic protection
    AS 1214-1983 Hot-dip galvanized coatings on threaded fasteners (ISO metric coarse thread series)
    AS 1746-1991 Conductors - Bare overhead - Hard-drawn copper
    AS 1566-1997 Copper and copper alloys - Rolled flat products (Reconfirmed 2018)
    AS 1931.1-1996 High-voltage test techniques - General definitions and test requirements
    AS 3100-1990 Approval and test specification - General requirements for electrical equipment
    AS 3191-1981 Approval and test specification for electric flexible cords (incorporating Corrigenda)
    AS 2187.2-1993 Explosives - Storage, transport and use - Use of explosives
    AS 1222.1-1992 Steel conductors and stays - Bare overhead Galvanized (SC/GZ)
    AS 2834-1995 Computer accommodation
    AS 1397-1993 Steel sheet and strip - Hot-dipped zinc-coated or aluminium/zinc-coated
    AS 2430.1-1987 Classification of hazardous areas - Explosive gas atmospheres
    AS 1874-1988 Aluminium and aluminium alloys - Ingots and castings
    AS 1449-1994 Wrought alloy steels - Stainless and heat-resisting steel plate, sheet and strip
    AS 3008.1-1989 Electrical installations - Selection of cables - Cables for alternating voltages up to and including 0.6/1 kV
    AS 2832.2-1991 Cathodic protection of metals - Compact buried structures
    AS 3000-1986 Electrical installations - Buildings, structures and premises (known as the SAA Wiring Rules) (incorporating Amdt 1)
    AS 1531.1-1974 Aluminium conductors for overhead power transmission purposes - All-aluminium conductors (AAC)
    AS 1432-1996 Copper tubes for plumbing, gasfitting and drainage applications

    Standards Referencing This Book - (Show below) - (Hide below)

    AS 4509.1-1999 Stand-alone power systems - Safety requirements
    AS 3015-1993 Electrical installations - Extra-low voltage d.c. power supplies within public telecommunications networks
    AS 3516.2-1998 Siting of radiocommunications facilities - Guidelines for fixed, mobile and broadcasting services operating at frequencies above 30 MHz
    AS/NZS 1596:2002 The storage and handling of LP Gas
    AS/NZS 3015:2004 Electrical installations - Extra-low voltage d.c. power supplies and service earthing within public telecommunications networks
    AS 2593-2004 Boilers - Safety management and supervision systems (Reconfirmed 2016)
    AS 3892-2001 Pressure equipment - Installation (Reconfirmed 2016)
    AS/NZS 4745:2004 Code of practice for handling combustible dusts
    AS 3600-2001 Concrete structures
    AS 2381.1-1991 Electrical equipment for explosive atmospheres - Selection, installation and maintenance - General requirements
    AS 2381.10-1995 Electrical equipment for explosive atmospheres - Selection, installation and maintenance - Equipment in combustible dust (Class II) areas
    AS 2834-1995 Computer accommodation
    AS 1020-1984 The control of undesirable static electricity
    AS 3600-1994 Concrete structures
    AS 2593-1995 Boilers - Unattended and limited attendance
    AS 1894-1997 The storage and handling of non-flammable cryogenic and refrigerated liquids (Reconfirmed 2021)
    AS 1418.1-2002 Cranes, hoists and winches General requirements
    AS/NZS 3080:1996 Telecommunications installations - Integrated telecommunications cabling systems for commercial premises
    AS 4326-1995 The storage and handling of oxidizing agents
    AS 4041-1992 Pressure piping
    AS 2832.3-1992 Cathodic protection of metals - Fixed immersed structures
    HB 29-1998 Telecommunications cabling handbook
    AS 4262.1-1995 Telecommunication overvoltages Protection of persons
    AS 4509.2-2002 Stand-alone power systems - System design guidelines
    AS 4509.3-1999 Stand-alone power systems - Installation and maintenance
    AS 3533.1-2009 Amusement rides and devices Design and construction
    AS 4070-1992 Recommended practices for protection of low-voltage electrical installations and equipment in MEN systems from transient overvoltages (Reconfirmed 2015)
    AS 2593-2001 Boilers - Unattended and limited attendance
    AS 3846-1998 The handling and transport of dangerous cargoes in port areas
    AS 3961-1991 Liquefied natural gas - Storage and handling
    AS 2832.2-2003 Cathodic protection of metals Compact buried structures
    AS 1418.13-1996 Cranes (including hoists and winches) Building maintenance units
    AS 3516.3-1991 Siting of radiocommunications facilities - Fixed location satellite earth stations
    HB 13-2000 Electrical equipment for hazardous areas
    AS 2832.4-1994 Cathodic protection of metals - Internal surfaces
    AS 1418.1-1994 Cranes (including hoists and winches) - General requirements
    HB 29-2000 Communications Cabling Manual, Module 2: Communications Cabling Handbook
    AS 3892-1995 Pressure equipment - Installation
    AS 2187.1-1998 Explosives - Storage, transport and use Storage
    AS 4262.2-1999 Telecommunication overvoltages Protection of equipment
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