AS 3007.51987

Australian Standard

Electrical installations Surfacemines and associated processingplant

Part 5: Operating requirements

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This Australian standard was prepared by Committee EL/33, Electrical Installations forOutdoor Sites Under Heavy Conditions (Including Opencast Mines and Quarries). It wasapproved on behalf of the Council of the Standards Association of Australia on27 February 1987 and published on 4 May 1987.

The following interests are represented on Committee EL/33:Association of Consulting Engineers AustraliaAustralian Electrical and Electronic Manufacturers AssociationAustralian Institute of Mining and MetallurgyConfederation of Australian IndustryDepartment of Industrial Relations, N.S.W.Department of Mines, QldDepartment of Mines, Tas.Electricity Supply Association of AustraliaMining Interests

Review of Australian Standards. To keep abreast of progress in industry, Australian Standards are subject toperiodic review and are kept up to date by the issue of amendments or new editions as necessary. It is importanttherefore that Standards users ensure that they are in possession of the latest edition, and any amendments thereto.Full details of all Australian Standards and related publications will be found in the Standards Australia Catalogueof Publications; this information is supplemented each month by the magazine The Australian Standard, whichsubscribing members receive, and which gives details of new publications, new editions and amendments, and ofwithdrawn Standards.Suggestions for improvements to Australian Standards, addressed to the head office of Standards Australia, arewelcomed. Notification of any inaccuracy or ambiguity found in an Australian Standard should be made withoutdelay in order that the matter may be investigated and appropriate action taken.

This Standard was issued in draft form for comment as DR 86011.

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AS 3007.51987

Australian Standard

Electrical installations Surfacemines and associated processingplant

Part 5: Operating requirements

First published 1987. . . . . . . . . . . . . . . . . . . . . . . . . . . .

PUBLISHED BY STANDARDS AUSTRALIA(STANDARDS ASSOCIATION OF AUSTRALIA)1 THE CRESCENT, HOMEBUSH, NSW 2140

ISBN 0 7262 4619 0

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PREFACE

This standard was prepared by the Associations Committee on Electrical Installations forOutdoor Sites Under Heavy Conditions (Including Opencast Mines and Quarries).It constitutes Part 5 of the AS 3007 series and is essentially identical with IEC 6215* whichwas prepared by the corresponding IEC Technical Committee, i.e. TC 71. Where thisstandard deviates technically from IEC 6215 by way of different or additional requirements,this is indicated by a rule in the margin against the clause, or part thereof, affected.A summary of such technical variations is given in the Annex.The Australian committee (EL/33) has actively participated in the work of IEC TC 71which has as its objective the development of uniform and internationally acceptable rules forthe safe use of electricity in opencast mines, quarries, stockpiles and the like. Suchapplications present particularly onerous conditions for the electrical apparatus and systems,including continual alteration of the location of the apparatus and systems, extension of theoperational area, and adverse environmental conditions. Because of the size of the plant andthe need for mobility, supply is frequently at high voltage over long distances, by means oftrailing cables. This should be compared with other industries where the electricalinstallations are generally fixed.The AS 3007 series specifies requirements for the installation and operation of electricalapparatus and systems in the abovementioned locations, with the object of ensuring thesafety of persons, livestock and property. AS 3007.1 outlines the scope of the compositestandard and provides definitions for some of the terms used. AS 3007.2 specifies themeasures which are required for protection against electric shock in normal service fromdirect contact with live parts; for protection against electric shock from parts which maybecome live in the event of a fault (indirect contact); and for protection against the effects ofovercurrent resulting from overload or short circuit conditions. AS 3007.3 specifies generalrequirements for the equipment and ancillaries associated with the electrical installation.AS 3007.4 sets out the requirements which are specific to particular installations, togetherwith any exemptions from the general requirements of AS 3007.2 and AS 3007.3 whichapply for such installations. AS 3007.5 (this standard) sets out the normal operatingprocedures which should be carried out to ensure the safety of personnel.The AS 3007 series recognizes several types of power supply system and specifies theprotective measures which are necessary for each system. Requirements for the protection ofpersonnel from indirect contact (see Section 2 of AS 3007.2) are based on the concept ofpermissible voltage versus time limits, which take into account the pathophysiologicaleffects of electric current passing through the human body, the typical industry conditions,and the probability of persons being in contact with the plant. In this and other respects theAS 3007 series differs in approach from the practically evolved requirements of AS 3000,SAA Wiring Rules.It will therefore be necessary for the regulatory authorities concerned to clearly delineate therespective areas of application for the AS 3007 series and for AS 3000.

* In course of publication based on IEC Document 71(Central Office)36.

Copyright STANDARDS AUSTRALIAUsers of Standards are reminded that copyright subsists in all Standards Australia publications and software. Except where the Copyright Act allowsand except where provided for below no publications or software produced by Standards Australia may be reproduced, stored in a retrieval system inany form or transmitted by any means without prior permission in writing from Standards Australia. Permission may be conditional on an appropriateroyalty payment. Requests for permission and information on commercial software royalties should be directed to the head office of StandardsAustralia.

Standards Australia will permit up to 10 percent of the technical content pages of a Standard to be copied for use exclusively inhouse bypurchasers of the Standard without payment of a royalty or advice to Standards Australia.Standards Australia will also permit the inclusion of its copyright material in computer software programs for no royalty payment providedsuch programs are used exclusively inhouse by the creators of the programs.

Care should be taken to ensure that material used is from the current edition of the Standard and that it is updated whenever the Standard is amended orrevised. The number and date of the Standard should therefore be clearly identified.The use of material in print form or in computer software programs to be used commercially, with or without payment, or in commercial contracts issubject to the payment of a royalty. This policy may be varied by Standards Australia at any time.Ac

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CONTENTSPage

SCOPE OF PART 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

REFERENCED DOCUMENTS 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 RESTRICTIONS ON ACCESS BY PERSONNEL 5. . . . . . . . . . . . . . . . . . . . 2 OPERATIONS INVOLVING PERSONNEL WORKING IN THE

VICINITY OF EXPOSED LIVE PARTS 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 MOVEMENT OF VEHICLES AND MACHINERY IN THE VICINITY OF

OVERHEAD LINES 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 OPERATIONS IN THE VICINITY OF COLLECTOR/TROLLEYWIRES 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 ALTERATIONS IN THE OPERATION 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 MOVING OF CABLES 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 PROTECTION OF CABLES 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 MOVING OF OVERHEAD LINES 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 ELECTRIC SHOTFIRING OPERATIONS 7. . . . . . . . . . . . . . . . . . . . . . . . .

10 FIRE PREVENTION 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 ADDITIONAL REQUIREMENTS AND PRECAUTIONS 7. . . . . . . . . . . . . . 12 TEMPORARY OPERATION OF EQUIPMENT 7. . . . . . . . . . . . . . . . . . . . . . APPENDIX A. RECOMMENDED MEASURES TO MINIMIZE THE

POSSIBILITY OF INADVERTENT INITIATION OFELECTRICALLY INITIATED EXPLOSIVE DEVICES 8. . . . . . .

ANNEX. SUMMARY OF TECHNICAL DEVIATIONS BETWEENTHIS STANDARD AND IEC 6215 10. . . . . . . . . . . . . . . . . . . . . . . . . . . .

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AS 3007.51987 4

STANDARDS ASSOCIATION OF AUSTRALIA

Australian Standardfor

ELECTRICAL INSTALLATIONS SURFACE MINES AND ASSOCIATEDPROCESSING PLANT

PART 5 OPERATING REQUIREMENTS

SCOPE OF PART

This standard specifies the normal operating procedures which should be carried out to ensurethe safety of personnel. These procedures may be varied in certain circumstances where aplanned operation is performed under controlled conditions.

NOTE: Attention is drawn to the fact that the requirements of Regulatory Authorit ies may dif fer from therequirements specified in this standard.

REFERENCED DOCUMENTS

The following standards are referred to in this standard:AS 2187.1 SAA Explosives Code

Part 1 Storage and Land Transport

AS 2187.2 SAA Explosives CodePart 2 Use of Explosives

AS 3007.2 Electrical Installations Surface Mines and Associated Processing PlantPart 2 General Protection Requirements

BS 6657 Guide to Prevention of Inadvertent Initiation of Electro-explosive Devices byRadio-frequency Radiation

IEC 621-5 Electrical Installations for Outdoor Sites Under Heavy Conditions (IncludingOpen-cast Mines and Quarries)Part 5: Operating Requirements.

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5 AS 3007.51987

1 RESTRICTIONS ON ACCESS BY PERSONNEL.1.1 Access to normal operating areas. All personnelmay have access to a normal operating area provided allbarriers and enclosures required by Section 1 ofAS 3007.2 are in place.Barriers or enclosures provided in accordance withClause 2.3 of AS 3007.2 shall be removed only by skilledor instructed persons, unless of the type described inItems (b), (c), (d) or (e) of that clause. When thesebarriers or enclosures are removed and the exposed liveparts are not isolated in accordance with Clause 2.3 ofthis standard, temporary barriers and warning signs shallbe installed.1.2 Access to electrical operating areas and closedelectrical operating areas. Only the following personsshall be permitted access to an electrical operating areaand a closed electrical operating area, unless all exposedlive parts in the area have been isolated in accordancewith Clause 2.3:(a) Skilled persons.(b) Appropriately instructed persons.(c) Ordinary persons when accompanied by skilled

persons or appropriately instructed persons.2 OPERATIONS INVOLVING PERSONNELWORKING IN THE VICINITY OF EXPOSED LIVEPARTS.2.1 General. When it is necessary to work in thevicinity of exposed live parts with voltages of more than50 V a.c. or 120 V d.c., either (a) the work shall be conducted observing the minimum

approach distances specified in Clause 2.2; or(b) the exposed live parts shall be isolated in accordance

with Clause 2.3; or(c) for instructed or skilled persons, the special

procedures prescribed in Clause 2.4 shall beobserved.

2.2 Minimum approach distances. Except wherepermitted by Clause 2.4, no part of any person or anyobject in contact with a person, other than speciallyinsulated operating devices, shall approach closer toexposed live parts than the distances specified in Table 1.

NOTES:1. The use of ropes, barriers or similar measures may be necessary

to facilitate observance of the minimum approach distances.2. The minimum approach distances specified in Table 1 are based

on work from a stable surface and exposed live parts which arefixed in position. Where these conditions do not apply thedistances should be increased to take account of the expectedmovement.

3. The minimum approach distances specified in Table 1 may needto be increased when working in the vicinity of overhead lines.

Particular care shall be taken when it is necessary forpersons working in the vicinity of exposed live parts touse long objects such as ladders, metal scaffolds, pipes,etc. It is recommended that such objects be carried in thehorizontal position by at least two persons.2.3 Isolation of exposed live parts. When it isnecessary to work in the vicinity of exposed live parts ina position giving less than the minimum approachdistances specified in Table 1, the power supply to theexposed live parts shall be isolated. However, thisrequirement shall not apply when instructed or skilledpersons are working to the procedure specified inClause 2.4.

TABLE 1MINIMUM APPROACH DISTANCES

FOR PERSONNEL

For installations with voltages of more than 1000 V,

Nominal voltage(phase-to-phase) * Minimum approach distance*

kV, r.m.s. mm1.13.36.6

9090

112233

120220320

66110150220

630110015002100

* The minimum approach distances specif ied take into accountthe fact that the system voltage may vary by up to 10 percentfrom the nominal voltage.

No minimum approach distance specified. Contact with livepart s is to be avoided.

isolation shall include short-circuiting and earthing ofthe parts concerned. A skilled person shall ensure thatthe isolation, short-circuiting and earthing have beensatisfactorily completed, and shall give authorizationbefore the commencement of any work. For testingpurposes the short-circuiting and earthing may betemporarily removed provided appropriate measures areadopted to ensure the safety of personnel.A skilled person shall ensure that all persons who areto work on the parts are fully conversant with the areaisolated and the work to be carried out. The skilledperson shall be aware of the possibility of dangerousvoltages being induced from adjacent energizedconductors and, where necessary, shall ensure thatappropriate precautions are taken.Where there are adjacent exposed live parts, theexposed live parts which have been isolated and, whereapplicable, short-circuited and earthed, shall be clearlyidentified and precautions taken to avoid contact withthe adjacent exposed live parts.2.4 Work on or in close proximity to exposed liveparts.2.4.1 General. When it is necessary to work on or inthe vicinity of exposed live parts with voltages of morethan 1000 V in a position giving less than the minimumapproach distances specified in Table 1, and it has beenestablished that it is not practical to isolate the parts inaccordance with Clause 2.3, work may be carried outwhilst the parts are live provided the measuresprescribed in Clauses 2.4.2 and 2.4.3 are taken.2.4.2 Responsible person. A skilled person shall bedesignated to be responsible for the operation. Beforepermitting work to commence the skilled person shallcarry out the following:(a) Prepare a detailed description of the nature and

location of the work to be carried out.(b) Prepare a detailed plan of the method and

sequence to be used including details of the workto be carried out by each person.

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AS 3007.51987 6

(c) Ensure that all persons involved are fully informedof their duties and the precautions to be carried out.

The skilled person shall ensure that each person involvedin the operation is under observation whilst the work iscarried out.2.4.3 Protective equipment. Suitable protective equip-ment shall be used and such equipment shall beperiodically tested to ensure continued effectiveness.

NOTE: Standards for tools and equipment for use in live-lineworking are in course of preparation by IEC Technical committeeNo 78, Tools for Live Working.

3 MOVEMENT OF VEHICLES AND MACHINERYIN THE VICINITY OF OVERHEAD LINES.3.1 General. The movement of vehicles and machineryin the vicinity of overhead lines shall be conducted insuch a way that the minimum clearances specified inClauses 3.2 and 3.3 are observed, excepting that theseclearances may be reduced in the special circumstancesdescribed in Clause 3.4.The minimum clearances specified in Clauses 3.2 and 3.3shall also be observed by persons on the vehicles ormachinery.The minimum clearances specified in Clauses 3.2 and 3.3do not apply where the overhead line has been isolated inaccordance with the procedure specified in Clause 2.3.3.2 Vertical clearances. The minimum clearancesspecified in Table 2 shall be observed when vehicles andmachinery pass under overhead lines. The clearancesapply from the highest point of the vehicles or machineryto the overhead lines.When it is necessary for vehicles or machinery to passunder overhead lines as part of their normal operation(i.e. at officially designated vehicular crossings) and thereis a likelihood that the minimum clearances specified inTable 2 cannot be maintained, height gauges, such asgoal posts, shall be provided at each side of the line toindicate the maximum height above the road surfacepermitted in terms of Table 2.3.3 Horizontal clearances. Where vehicles or mach-inery are operated in the vicinity of overhead lines andthe height of the vehicles or machinery is such that theminimum vertical clearances specified in Clause 3.2cannot be achieved, a horizontal clearance of not lessthan the appropriate value specified in Table 2 shall bemaintained. Where the horizontal movement of thevehicles or machinery cannot be adequately controlled,larger horizontal clearances shall be maintained.3.4 Permissible reduction of clearances. The clear-ances specified in Clauses 3.2 and 3.3 may be reducedwhere any one of the following circumstances exist:(a) Where the vehicles or machinery move in a defined

path, e.g. rail-mounted vehicles.(b) Where the movement of the vehicles or machinery

is under the supervision of an instructed or skilledperson.

(c) Where the measures for protection against indirectcontact specified in AS 3007.2 are applied to thevehicles or machinery.

4 OPERATIONS IN THE VICINITY OF COLLEC-TOR/ TROLLEY WIRES. (Requirements yet to bedeveloped.)

TABLE 2MINIMUM CLEARANCES FOR THE

MOVEMENT OF VEHICLES ANDMACHINERY UNDER AND IN THE VICINITY

OF OVERHEAD LINES

5 ALTERATIONS IN THE OPERATION.

Nominal voltage(phase-to-phase) *

kV, r.m.s.Minimum clearance *

mm

1.1> 1.1 33> 33 66> 66 110> 110 220

10002300250030004000

* The minimum clearances specif ied take into account the factthat the system voltage may vary by up to 10 percent from thenominal voltage.

Allowance should be made for the possible sag and swing ofthe line.

5.1 Preservation of protection. Care shall be takento ensure that the protection required by AS 3007.2 ismaintained when the operation is altered. Suchalterations may include extending the area of operation(requiring longer power lines or cables), construction ofroads, addition of equipment, etc. Matters to beconsidered include clearances, guarding of electricalinstallations, protective conductor size, overload andshort-circuit protection, undervoltage, exposure tolightning, prospective touch voltages, etc.5.2 Reduction of clearances. Particular care shall betaken to ensure that the clearance of overhead lines toground is not reduced below the minimum valuespermitted by dumping or tipping of material,landscaping, or by creating storage areas, or by thepositioning of buildings or structures.5.3 Excavation near electrical installations.Excavation for the extraction of minerals or any otherpurpose shall not affect the security of the foundationof any pole, tower or other support, nor disturb earthingconductors or electrodes.5.4 Integrity of safety circuits and safety devices.Precautions shall be taken to ensure that safety circuitsor safety devices are not rendered inoperative unlessalternative safety measures are implemented.6 MOVING OF CABLES.6.1 Movable distribution cables. All movabledistribution cables shall be isolated before relocation iscommenced unless of a type which is specificallydesigned to be moved whilst energized. Movement ofthe cables shall be carried out in accordance with themanufacturers recommendations regarding themaximum tension and the minimum temperature andbending radius.Before reconnecting cable coupling boxes they shall beinspected and tested where appropriate to ensure thatgood conductivity and insulation is maintained.6.2 Trailing cables and reeling cables. Wheretrailing cables and reeling cables are moved by amachine, means shall be provided to prevent directstrain being taken by the cable terminations at themachine. Movement of the cables shall be carried out

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7 AS 3007.51987

in accordance with the manufacturers recommendationsregarding the maximum tension and the minimumtemperature and bending radius.

For trailing cables it is recommended that an excessactive cable length be provided close to the machine, andthat such excess cable be stored in a figure of eight orzig-zag configuration.All trailing cables and reeling cables shall be so locatedthat damage by rocks, stones, etc., will be minimized. Alltrailing cables and drum cables shall be examined atregular intervals to ensure freedom of movement andfreedom from damage.Where the movement of trailing cables and reeling cablesrequires separation of cable couplers, the cable shall beisolated before the work is commenced. However, thisrequirement does not apply for low-voltage, low-currentapplications, e.g. control cables.

7 PROTECTION OF CABLES. Cables which may besubject to damage as a result of the movement of vehiclesand machinery shall be conspicuously located orappropriately protected. Such protection may take theform of (a) use of ramps and covers;(b) covering with suitable loose material;(c) warning flags, markers or fences;(d) earth embankments;(e) burying in pipes under defined roads;(f) overhead cable bridges; or(g) supporting cables above ground level.8 MOVING OF OVERHEAD LINES. Before movingan overhead line, all conductors shall be isolated inaccordance with the procedure specified in Clause 2.3.In the event of an electrical storm in the area of theoverhead line all work on the line shall cease.When persons are working above ground appropriateprecautions shall be taken to minimize the risk of falling,e.g. use of safety belts.Precautions shall be taken to ensure that all poles ortowers are structurally sound and that releasing theconductors will not cause instability to other sections ofthe line.All vehicles and machinery shall be prevented frompassing under or over a line during dismantling anderection unless appropriate protective measures are taken.

The removal of used poles from their original locationshall be carried out in a manner which will notendanger the personnel involved.All poles shall be examined along their full lengthbefore re-erection, including insulators and cross arms.The re-erecting of overhead line poles shall be carriedout on substantial and solid ground.Before re-erection conductors shall be examined toensure their suitability for re-use.9 ELECTRIC SHOT-FIRING OPERATIONS.Where electrically initiated explosive devices are usedcare shall be taken to guard against the danger ofinadvertent initiation, or misfires, caused by the inputof electrical energy from any source other than theintended initiating source.

NOTE: Electrical current can flow in earth paths for a variety ofreasons. Such currents, usually described as stray currentsconstitute possible initiating sources for electrically initiatedexplosive devices. Recommended measures to minimize thepossibility of inadvertent initiation of electrically initiatedexplosive devices are set out in Appendix A. Attention is alsodrawn to requirements for the storage and use of explosives inAS 2187.1 and AS 2187.2, respectively.

10 FIRE PREVENTION. (Requirements yet to bedeveloped.)11 ADDITIONAL REQUIREMENTS AND PRE-CAUTIONS.11.1 Precautions during lightning storms. De-energized cables or overhead lines shall not be handledor repaired during lightning storms where there is apossible hazard from direct strikes or from inducedvoltages.11.2 Warning notices. Warning notices shall beprovided to draw attention to potential hazards and shallbe properly maintained.11.3 Removal of guards. Protective guards andenclosures shall be removed only when absolutelynecessary and when appropriate precautions have beentaken. Provision shall be made for prompt replacementof such guards and enclosures on completion of thework.11.4 Operations involving long metallic structures.Care shall be taken when long metallic structures (e.g.movable conveyors, pipeline systems) are run parallelto overhead lines because of possible hazards frominduced voltages.12 TEMPORARYOPERATION OF EQUIPMENT.Temporary installations shall comply with the generalprotection requirements of AS 3007.2.

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AS 3007.51987 8

APPENDIX ARECOMMENDED MEASURES TO MINIMIZE THE POSSIBILITY OF INADVERTENT

INITIATION OF ELECTRICALLY INITIATED EXPLOSIVE DEVICES(See Clause 9)

A1 GENERAL PRECAUTIONS. Procedures which may be used to guard against premature initiationof electrically initiated explosive devices include:(a) The use of adequately insulated initiation cables.(b) Avoidance of cable joints wherever possible.(c) Ensuring that joints are staggered in adjacent cores and are mechanically secure and well insulated.(d) Making the final connection to the initiating device only when the device is about to be used. At all

other times the initiating cables should be short-circuited and insulated from earth.(e) Use of frequency sensitive detonators and initiating devices. Such devices are responsive to high

frequency (15 000 Hz) only and are insensitive to frequencies of 50 Hz to 60 Hz.The recommendations of Clauses A2 to A9 inclusive outline specific additional measures which may beused to minimize the possibility of inadvertent initiation.

A2 IT SYSTEMS WHICH CONTINUE TO OPERATE UNDER FIRST FAULT CONDITIONS.Electrically initiated explosive devices should not be stored or used in the vicinity of any electricalinstallation which is permitted to continue to operate under first fault conditions (see Clause 11.4 of AS3007.2).

A3 EXPOSED CONDUCTIVE PARTS AND EXTRANEOUS CONDUCTIVE PARTS. Electricallyinitiated explosive devices and connecting cables should not be used in the vicinity of exposed conductiveparts and extraneous conductive parts to avoid premature initiation due to the possibility of voltagesappearing on those parts in normal operation, e.g. from the use of PEN conductors, or under faultconditions.

A4 OVERHEAD LINES. Electrically initiated explosive devices and connecting cables should not beused in the vicinity of overhead lines. Stray currents can be induced in the cables during fault conditionson the overhead line or in normal operation in the case of single wire earth return (SWER) lines. Anadditional hazard exists due to the possibility of overhead lines falling to the ground.

A5 GALVANIC EFFECTS. The contact of dissimilar metals in an electrolytic environment (e.g.ground water, drilling mud) will produce an electric current. The use of metal liners, metal loading sticksor other conductive parts should therefore be avoided.

A6 CATHODIC PROTECTION. Particular care should be taken when using electrically initiatedexplosive devices in the vicinity of pipelines and other structures which are provided with cathodicprotection.

A7 ELECTROMAGNETIC RADIATION. High frequency energy from radio, television, radar, etc.,can under certain conditions, cause initiation of electrically initiated explosive devices. It is recommendedthat portable radio transmitters not be used in the vicinity of electrically initiated explosive devices andconnecting cables. Cognizance should be taken of any fixed transmitting stations in the vicinity.

NOTE: Guidance on the prevention of inadvertent initiation of electrically initiated explosive devices by radio-frequencyradiation is provided in BS 6657.

A8 STATIC ELECTRICITY. Static electricity charges may be generated by dust storms, snow storms,moving conveyor systems, pneumatic loading systems, etc. If generated charges are allowed to accumulateand/or store on a person or object there is a possible danger of discharge into electrically initiatedexplosive devices.

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9 AS 3007.51987

It is recommended that shot-firing be suspended during dust storms or snow storms and that accumulationof static charges be avoided by connecting to earth all persons or equipment on which a static charge mayaccumulate. The electrical resistance of the earth connection should be high enough to restrict current flowyet low enough to dissipate the static charge (usually a resistance value of 10 MW is adequate for thispurpose). This recommendation may be achieved by the use of semi-conductive products for personalfootwear, hoses to pneumatic loading systems and conveyor belts.

A9 LIGHTNING. Atmospheric disturbance can initiate electrically initiated explosive devices byinducing a current in the firing circuit. It is recommended that laying or firing operations be suspended,and personnel withdrawn from the area during lightning storms.

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AS 3007.51987 10

ANNEXSUMMARY OF TECHNICAL DEVIATIONS BETWEEN

THIS STANDARD AND IEC 621-5

General. Throughout the text reference has been made to applicable Australian standards in lieu of IECPublications.

Scope. A note has been added warning that the requirements of Regulatory Authorities may differ fromthe requirements of this standard.

Table 1. The minimum approach distances have been revised to align with the clearance distancesspecified in Table 1 of AS 3007.2 which differ from the corresponding values in IEC 621-2. The approachdistances specified have been related to values of nominal system voltage in use within Australia.

Table 2. The minimum clearances have been related to values of nominal system voltage in use withinAustralia.

Clause 5.2. The words or by the positioning of structures or buildings have been added at the end ofthe clause.

Clause 6.1. In the second sentence, reference has been made to the maximum tension to be applied inthe relocation of movable distribution cables.

Clause 6.2. A sentence has been added to the first paragraph (same as existing in Clause 6.1) concerningthe manufacturers recommended parameters for the movement of trailing cables and reeling cables.

Clause 8. The third paragraph of the clause has been amended to accord with Australian practice forwork on overhead lines.

Appendix A Clause A3. The clause has been clarified to indicate that voltages may be transferredto exposed conductive parts and extraneous conductive parts both in normal operation and under faultconditions.

Appendix A Clause A4. Reference has been added to the possibility of stray currents being inducedin normal operation in the case of single wire earth return (SWER) lines.

Appendix A Clauses A5 and A6. The two clauses have undergone minor revision to clarify therecommendations.

Appendix A Clause A7. A note has been added referring to a relevant British Standard.

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AS 3007.5-1987 Electrical installations - Surface mines and associated processing plant - Operating requirements

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