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General Clarification of New CENELEC (European Standard) BS EN 62305 Series for UK Protection Against Lightning
As the majority of the Construction Industry and Engineering will be aware, British Standard 6651:1999 “The Protection of Structures Against Lightning” will be replaced by a suite of European Standards designated BSEN 62305-1-2-3 and 4, (published September 2006) and will run parallel with BS6651 1999 until August 2008 when BS6651 will be withdrawn.
This risk assessment as defined in BS EN-62305-2 will now take account of the many and varied aspects of the structure and its content, for example:
- Environmental Influences (Ng Factors, Soil Resistivity, Location etc)
- Structural Attributes (Building Dimensions, Spacial Shielding etc)
- Conductive Service Lines (Power, Telecom, Equipment Withstand etc)
- Zoning (Location, Fire Risk Level, Fire Protection Systems etc)
- Loss Allocation (Special Hazards, Type of Business etc)
with the ultimate aim being to determine the actual risk to the structure and as a consequence the protection level required ie (Level 1, 2, 3 or 4) and In respect of BSEN 62305-2 “RISK MANAGEMENT” we are pleased to confirm that our designers and production staff are the first to receive and be trained in the use of Furse/Thomas and Betts Strike Risk Software.
Future Lightning Protection System Design will be determined by the correct input of Weighting Factors into the risk management analysis (BS EN 62305-2), which will indicate the level of structural and Transient Over Voltage Devices required to reduce the risk to tolerable levels.
The basic principles and methodology of Lightning Protection illustrated in BS EN-62305 series generally reflects current UK Lightning Conductor System Custom and Practice, for example, BS6651 identifies three principles of Lightning Protection, in effect: the Faraday Cage concept (Mesh), Rolling Sphere and Protective Angle methods and these principles are also identified in BS EN-62305 series relative to the protection level.
As EN-62305 documents will become common to all CENELEC member countries it is clearly impractical for this standard to accommodate all the variables that each country adopts within the practical application of Lightning Protection Design, and as a consequence it is fair to say that many of the figures and examples shown in the EN-62305 series will have been derived from such standards as British Standard 6651 or German National Standard VDE0185 and as such UK lightning conductor system installation practice will generally remain unchanged.
It is recognised that the UK normative for Lightning Conductor System Design (BS6651) generally adopts the Faraday Cage (Mesh) principle, using either metallic elements of the structure, conductor tapes or a combination of both, and when designed by trained and accredited lightning conductor system designers these systems have provided excellent functional structural lightning protection for the UK environment over generations.
Examples of differing installation principles however could be shown where say other European National Standards hold roof conductors away from roof finishes, where in the UK these conductors are laid flat to the finished material, again other European countries favour the use of finials to protect metalwork, plant etc at roof level (these finials reaching several metres in height for specific applications), where the UK normative and aesthetics result in direct bonding of metalwork of sufficient gauge to the lightning conductor system, taking account of dangerous transient voltage’s which may be induced into the building.
Whilst British Standard 6651 provides for total protection to the structure there has always been a risk to the clients electronic equipment. Unfortunately Electronic Systems Protection is an optional element of BS 6651 (Annex C) and is rarely incorporated fully into the Protection Measures. BS EN-62305-4 however is specifically aimed at the protection of sensitive electronic equipment and offers several options for eliminating any potential damage caused by Lightning and Electrical Switching effects and is now an integral part of the Risk Management Solution and Final Certification.
It is considered extremely important for UK business to understand the complex nature of these new standards and as a consequence the need for lightning conductor system specialists to be competent in the proper design and installation of these new lightning and Surge Protection standards. In this respect we are ensuring that all our staff who are involved in lightning conductor and surge protection design and installation participate in our Federation (ATLAS) ongoing BSEN 62305 workshops and ultimately their registration as accredited designers/installers.
It is essential to ensure early and regular consultation between the lightning protection system designers and the building contractor, electrical contractor, consulting engineers etc if the structure is to be designed and costed correctly and receive the correct protection level required at planning stage.
In keeping with our policy of delivering a professional service of the highest standard we will continue to work with clients from project inception to completion providing high quality and technically accurate solutions to industry across all disciplines within BEST Services Ltd.
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