FAQ’s – Lightning Protection

  • The British standard for lightning protection is the current edition of BS EN 62305 – Protection against lightning
  • It is the British edition of the European standard (both are derived from IEC 62305) to which all lightning protection systems to new structures, and new extensions to existing ones, are designed, installed and maintained
  • BS EN 62305 was first introduced in 2006 and replaced BS 6651:1999 from 1st September 2008
  • New versions of Parts 1, 3 and 4 of BS EN 62305 were issued in 2011; followed by a new version of Part 2 in 2012
  • A lightning protection system is required if it is determined that there is sufficient risk of a lightning related event causing harm and damage to a structure, the people in and around it and the systems on and within it
  • The need for protection and the economic benefits of selecting and installing adequate protective measures should be determined in terms of risk management (by assessment)
  • However, the decision to provide a lightning protection system can be taken regardless of the outcome of risk assessment, where there is a desire that there be no avoidable risk; or where protection against lightning is required by the authority having jurisdiction
  • The component parts of a lightning protection system are the external:
    • air termination system – this intercepts a lightning flash
    • down conductor system – this conducts the lightning current to earth
    • earth termination system – this disperses the lightning current into the earth
  • Plus primary internal protection measures, such as equipotential bonding, to prevent dangerous sparking and the ingress of lightning currents, via cables and services
  • Additional protection measures can be used to reduce the risk of damage to electrical and electronic systems from the effects of lightning electromagnetic impulse (LEMP)
  • These include:
    • Earthing and bonding
    • Magnetic shielding
    • Line routing
    • Isolating interfaces
    • Coordinated transient over-voltage SPDs
  • All conventional lightning protection systems follow the Faraday Cage principle of creating a protected volume around an object (structure) or an area considered to be at, or containing items at, risk from lightning related events
  • There are two fundamental types of lightning protection system
    • An isolated lightning protection system is where components are separate from, and arranged so as to create a volume within which, the protected object or area is located; and where these are physically and electrically isolated from each other
    • A non-isolated lightning protection system is where components are arranged on, and sometimes form part of, the object to be protected; and where these are not physically and electrically isolated from each other
  • Lightning protection systems should be periodically inspected and tested in accordance with the requirements of the British standard in force at the time of the original installation; at a point in time when an existing system was either reassessed, amended or upgraded
  • If the above is not known then the current British standard should be used
  • Currently, this is carried out on an annual basis
  • No, as the United Kingdom will remain part of CENELEC and the wider IEC technical committees, irrespective of what happens
  • Omega has representation on National (BSI), European (CEN) and International (IEC) Technical Committees
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