IEC_62305-3_232_DC.pdf

81/232/DCFor IEC use only2003-07-25INTERNATIONAL ELECTROTECHNICAL COMMISSIONTECHNICAL COMMITTEE No.81:LIGHTNING PROTECTIONIEC 62305-3,Ed.1:Protection against lightning-Part 3:Physical damage to structures andlife hazardThis document is relevant to new material submitted by some National Committees as commentsto 81/214/CD and judged by WG 8 useful to be integrated in the future CDV.National Committees are asked to submit their comments as soon as possible in order to allow WG8 to examine it before the next TC 81 meeting in Palma de Mallorca(2003 September 29).Comments should be submitted using the IEC Electronic voting/commenting system by theNational Committees(See AC/15/2001).Comments to be returned by 2003-09-19.2 81/232/DCAnnex E(informative)Additional information for LPS in the case of of structures with danger ofexplosion1Scope1.1 This annex applies to the design,erection,extension and modification of lightning protectionsystems for structures with explosion endangered areas.This annex does not contain anydata regarding the necessity of lightning protection.1.2 This annex applies only in conjunction with IEC 62305-3,Ed.1.0“Protection against lightning-Part 3 Physical damages to structures and life hazard”.1.3 If a lightning protection system is designed according to lightning protection class 2,thiscomplies with the usual requirements for explosion endangered areas.Exceptions to this areallowed only in justified exceptional cases or under special conditions,e.g.extremeenvironmental influences,climatic conditions or legal provisions.The following additionalrequirements are based on lightning protection class 2.NOTE:The requirements are based on practically proven configurations of lightning protection systems in explosionendangered areas.2Terms and definitionsFor hazardous areas,the terms and definitions of IEC 60079-10“Electrical apparatus for explosivegas atmospheres Classification of hazardous areas“and of IEC 61241-3“Electrical apparatus foruse in the presence of combustible dust Classification of areas where combustible dusts are ormay be present”apply in addition to the terms and definitions of IEC 62305-3,Ed.1.0.3 GeneralIf a lightning protection system is erected in accordance with this standard,inflammable sparks aswell as deranging or damaging influences on electrical equipment can not always be avoided incases of lightning influence.The lightning protection system shall be carried out in such a way that,in case of a lightning stroke,there are no melting or spraying effects except at the striking point.For the planning of the lightning protection systems,the operator shall supply drawings of the plantsto be protected,where the explosion endangered areas with zones according to IEC 60079-10 andIEC 61241-3 are to be marked.4 Structures containing solid explosive materialsFor these structures,an isolated external LPS should be used(see 5.1.2).Any part of the external LPS should be at least 1 m away from a hazardous zone.A hazardous zoneshould not be directly under a metal sheet,which may be punctured by lightning(5.2.5)nor shouldit be under a conductor from which melted metal may fall.3 81/232/DCConductors passing near a hazardous zone should be continuous or connections should be madewith compression fittings or by welding.Arrangement type B for earth termination system,designed according to the type I LPS,ispreferable(see 5.4.2.2).Lightning equipotential bonding between LPS components and other conductive installations,aswell as between the components of all conductive installations,according to 6.2,should be assuredinside the hazardous zone:at ground level where the separation distance between the conductive parts is less than the safety distancecalculated assuming kc=1.Lightning equipotential bonding is not needed if the structure is protected by a continuous cage witha mesh width not greater than 0,1 m.Surge protection devices should be preferably positioned outside the hazardous zone.Surge protection devices positioned inside the hazardous zone shall be of explosion-proof type.5Refinery,tanks and pipelines5.1GeneralSoil covered tanks and pipelines do not need an external lightning protection.For measuringequipment inside the tanks 3.3.3.2 shall be taken into account.Common equipotential bonding shall be provided for the lightning protection system according toIEC 62305-3,Ed.1.0 and for the installations in explosion endangered areas according toIEC 60079-10 and IEC 61241-3.Besides leads according to IEC 62305-3,Ed.1.0,tables 5 and 6,also pipelines,which areconnected electrically conductive may be used as connection lines between metal parts and earthelectrodes.Connections to pipelines shall be of such a kind,that in case of a lightning current passage there isno sparking.Suitable connections to pipelines are welded on lugs or bolts or tapholes in the flangesfor taking up screws.Connections by means of clips are only allowed if ignition protection in case oflightning currents is proved by te