AS NZS 1768 PDF

For many decades, the principals and senior management of LPI have been providing specialist lightning protection advice to customers in some of the most. Visit our website and learn more about AS/NZS standards. You may require this Standard if you are an electricity network operator or electrical contractor and intend to: design; construct; commission.

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We are a non-profit group that run this website to share documents. We need your help to maintenance this website. Please help us to share our service a your friends. This Standard was published on 10 January The following are represented on Committee EL To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be nzx. It is important that readers assure themselves they are using a current Standard, which should include any amendments which may have been published since the Standard was purchased.

Alternatively, both organizations publish an annual printed Catalogue with full details of all current Standards. For more frequent listings or notification of revisions, amendments and withdrawals, Standards Australia and Standards New Zealand offer a number of update options. For information about these services, users should contact their respective national Standards organization.

We also welcome suggestions for improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Please address your comments to the Chief Executive of either Standards Australia or Standards New Zealand at the address shown on the back cover. This Standard was issued in draft form for comment as DR No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher.

This Standard is intended to provide authoritative guidance on the principles and practices of lightning protection for a wide range of structures and systems. It is not intended for mandatory application but, if called up in a contractual situation, compliance with this Standard requires compliance with all relevant clauses of the Standard such that the level of protection will be sufficient to achieve a tolerable level of risk as determined by the risk calculation.

In general, it is not economically possible to provide total protection against all the possible damaging effects of lightning, but the recommendations in this Standard will reduce the probability of damage to a calculated acceptable level, and will minimize any lightning damage that does occur.

Guidance is given on methods of enhancing the level of protection against lightning damage, if this is required in a particular situation. Where a new structure is to be erected, the matter of lightning protection should be considered in the planning stage, as the necessary measures can often be affected in the architectural features without detracting from the appearance of the building.

In addition to the aesthetic considerations, it is usually less expensive to install a lightning protection system during construction than afterwards. The decision to provide lightning protection may be taken without carrying out a risk assessment or regardless of the outcome of any risk assessment, for example, where there is a desire that there be no avoidable risk.

Any decision not to provide lightning protection should only be made after considering the advice provided in this Standard. Where doubt exists as to the need for lightning protection, further advice should be sought from a lightning protection designer or installer. Unless it has been specified that lightning protection must be provided, the first decision to make is whether the lightning protection is needed.

Section 2 provides guidance to assist in this decision. Section 3 provides advice on the protection of persons from lightning, mainly relating to the behaviour of persons when not inside substantial buildings. Once a decision is made that lightning protection is necessary, Section 4 provides details on interception lightning protection for the building or structure. This includes information on the size, material, and form of conductors, the positioning of air terminals and downconductors, and the requirements for earth terminations.

Persons and equipment within buildings can be at risk from the indirect effects of lightning and Section 5 gives recommendations for the protection of persons and equipment within buildings from the effects of lightning.

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Section 6 describes methods of lightning protection of various items not covered in earlier sections, such as communications antennas, chimneys, boats, fences, and trees. A clause is included on methods for protecting domestic dwellings and assorted structures in public places, where a complete protection system may not be justified, but some protection is considered desirable. Section 7 sets out recommendations for the protection of structures with explosive or highly-flammable contents.

Section 8 gives advice on precautions to be taken during installation, inspecting, testing, and maintaining lightning protection systems.

Standards Catalogue

A number of appendices are included that provide additional information and advice. The appendices form an integral part of this Standard unless specifically stated otherwise. The recommendations specifically cover the following applications: 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. This Standard is applicable to conventional lightning protection systems LPSs that comprise air terminals, downconductors, earth termination networks and surge protective devices SPDs.

Nothing contained within this Standard either endorses or implies the endorsement of non-conventional LPSs that comprise air terminals that claim enhanced performance or downconductors that claim enhanced magnetic screening over conventional systems. The performance of such systems is outside the scope of this Standard.

Irrespective of claimed performance, air terminals shall be placed in accordance with Section 4 to comply with this Standard. Compliance with the recommendations of this Standard will not necessarily prevent damage or personal injury due to lightning but will reduce the probability of such damage or injury occurring.

Direct and nearby cloud-to-ground lightning discharges can be hazardous to persons, structures, installations and many other things in or on them.

Consideration should always be given to the application of lightning protection measures. Until about ten years ago, risk assessment was used to determine if there was a need to provide lightning protection. However, the modern approach is that of risk management, which integrates the determination of the need for protection with the selection of adequate protection measures to reduce the risk to a tolerable level.

This selection takes into account both the efficiency of the measures and the cost of their provision. In the risk management approach, the lightning threats that create risk are identified, the frequencies of all risk events are estimated, the consequences of the risk events are determined, and if these are above a tolerable level of risk, protection measures are applied to reduce the risk R to below the tolerable level Ra. This involves a choice from a range of protection level efficiencies for protection against direct d strikes to the structure and decisions about the extent of other measures for protecting low-voltage and electronic equipment against indirect i lightning stresses incident from nearby strikes.

The lightning protection measures include an LPS for the structure and its occupants, protection against the lightning electromagnetic pulse LEMP caused by direct and nearby strikes, and transient protection TP of incoming services. The LPS for the structure comprises an air terminal network to intercept the lightning strike, a downconductor system to conduct the discharge current safely to earth and an earth termination network to dissipate the current into the earth.

The LEMP protection includes a number of measures to protect sensitive electronic equipment such as the use of a mesh of downconductors to minimize the internal magnetic field, the selection of lightning protection zones, equipotential bonding and earthing, and the installation of SPDs.

The TP for incoming services includes the use of isolation devices, the shielding of cables and the installation and coordination of SPDs. It is a relatively complex function and depends onβ€” a the resistance component R as measured by an earth tester; b the reactance component Xdepending on the circuit path to the general body of earth; and c a modifying reducing time-related component depending on soil ionization caused by high current and fast rise times.

All parts below the lowest test link in a downconductor are included. The term refers exclusively to the danger arising from ignition.

Where danger from other causes such as toxicity, asphyxiation, and radioactivity may arise this is specifically mentioned. It consists of both external and internal LPSs and is defined as a set of construction rules, based on corresponding protection level.

Extra protection is applied at the zone boundary to minimize the risk of damage to equipment inside nz zone. It may be composed of one or more simple probabilities of damage. For each protection level, a set of maximum sizing criteria and minimum interception criteria lightning current parameters is fixed, together with the corresponding rolling sphere radius. It is based on determining the likely number of lightning discharges and also estimates the probability and consequences.

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A range of protection measures can be selected to reduce the risk to less than a target value. This process is also known as risk management. Thunderstorm occurrence at a particular location is usually expressed in terms of the number of calendar days in a year when thunder nze heard at the location, averaged over several years. Also referred to as acceptable risk, being the maximum value of risk acceptable based on community expectations.

Lightning can cause damage to all or part of a structure or to the contents of a structure, especially to electrical and nzx systems. Consequential effects of lightning damage may extend to the surroundings of a structure. To reduce lightning damage and its consequential effects, lightning protection measures may be required.

The need for protection and the level of protection applied should be considered in terms of the assessment of risk due to lightning, and management of that risk to an acceptable level. The approach outlined in this section is based on the principles of the management of risk due to lightning outlined in initial work by IEC Committee TC 81 on this subject. The risk assessment calculator is a simplified tool for the more common structure types.

For specialized structures e. This may involve the application of industry specific Standards. A decision to provide lightning protection may be taken regardless of the outcome of any risk assessment, for example, where there is a desire that there be no avoidable risk.

It may also be important to specify other protection measures such as SPDs on incoming conductive electrical service lines and internal equipment. Risk assessment for protection of specific conductive electrical services may also be undertaken in isolation based on specific Standards and performance criteria.

For telecommunication overvoltages, AS Before any decision is made not to install lightning protection to a structure, consideration should be given to the factors outlined in other sections of this Standard.

The object of this Section is to give a procedure for evaluation of the risk to a structure, people and installations or equipment in, on or connected to the structure.

AS / NZS Lightning Protection – AG – Australian Business Licence and Information Service

This evaluation considers mechanical damage of the structure and contents, damage and failure of equipment, potential differences causing deaths of people and livestock from step and touch voltages, and fire damage that may result from the lightning discharge. This Standard does not consider the risk of personal injury when using telecommunication equipment during a lightning storm. Expressed as a number, it represents the probability of loss occurring over the period of a year.

Thus a risk of 10 -3 represents a chance of 1 in of a loss occurring during a year. To increase understanding of the risk concept, some risks associated with everyday living are provided in Table 2. Nza human activities imply a judgement that the benefits outweigh the related risks. Only applicable to structures involved in the provision of public service utilities e. In relation to human fatalities, various societal risk guidelines or criteria have been proposed.

Generally for a single human fatality, risks of greater than 10β€”3 per year i. Public money would normally be spent to 17688 to eliminate or reduce to a level as low as reasonably practical the causes of risks greater than 10β€”4 per year i.

Risks less than 10 β€”5 per year i. In terms of the risk of various types of losses due to lightning, a value of the tolerable risk, R a needs to be specified. For each type of loss due to lightning, R a represents the tolerable probability of that loss occurring over the period of a year.

Regarding the potential types of risk due to lightning listed in Clause 2. For example, at a particular facility, it may be considered that a chance of 1 in of economic loss due to lightning occurring over a period of a year is tolerable. Alternatively, this would mean that it is considered acceptable for 17768 a loss to occur, on average, once every years.