Lightning Protection Standard BS EN 62305

BS 6651:1999 Protection of structures against lightning has been the cornerstone for
guidance on design and installation of lightning protection since 1985. In September 2006. however, a new standard BS EN 62305 was introduced and is now the only recognised standard for lightning protection.

The new standard reflects increased scientific understanding of lightning and its effects over the last twenty years, and takes stock of the growing impact of technology and electronic systems on our daily activities. More complex and exacting than its 118 page predecessor, the 475-page BS EN 62305 is structured as a series with four parts (see below), starting at general principles, then risk management, through to damage to the structure and damage to electronic systems therein.

Key to the new standard is that all considerations for lightning protection are driven by a comprehensive and complex risk assessment and that this assessment not only takes into account the structure to be protected, but also the services to which the structure is connected.

In essence, structural lightning protection can no longer be considered in isolation, protection against transient overvoltages or electrical surges are integral to the new standards.
 

Part 1: General Principals

BS EN 62305-1 (part 1) is an introduction to the other parts of the standard and essentially describes how to design a Lighting Protection System (LPS) in accordance with the accompanying parts of the standard.
 

Part 2: Risk Management

BS EN 62305-2 (part 2) risk management approach, does not concentrate so much on the purely physical damage to a structure caused by a lightning discharge, but more on the risk of loss of human life, loss of service to the public, loss of cultural heritage and economic loss.
 

Part 3: Physical damage to structures and life hazard

BS EN 62305-3 (part 3) relates directly to the major part of BS 6651. It differs from BS 6651 in as much that this
new part has four Classes or protection levels of Lightning Protection System (LPS), as opposed to the
basic two (ordinary and high-risk) levels in BS 6651.
 

Part 4: Electrical and electronic systems within structures

BS EN 62305-4 (part 4) covers the protection of electrical and electronic systems housed within structures. This
part essentially embodies what Annex C in BS 6651 conveyed, but with a new zonal approach referred to as
Lightning Protection Zones (LPZs). It provides information for the design, installation, maintenance and
testing of a Lightning Electromagnetic Impulse (LEMP) protection system for electrical/electronic systems
within a structure.

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