The I.S. EN 62305 standard for lightning protection in Ireland was originally published in September 2006, to supercede the previous standard, BS 6651:1999 that was the British standard prior to the introduction of I.S. EN 62305. First issued in 1985, it was revised in 1992, 1999 and further amended in 2005; before being withdrawn on 31st August 2008.

I.S. EN 62305

The I.S. EN 62305 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 predecessor, I.S. EN 62305 includes four distinct parts – Part 1 General Principles, Part 2 Risk Management, Part 3 Physical Damage to Structures and Life Hazard, and Part 4 Electronic Systems Protection.

I.S. EN 62305 – Protection against lightning

IEC 63205 is the recognised worldwide standard for lightning protection system (LPS) design, installation and maintenance. I.S. EN 62305 is the Irish edition of the European standard, and is derived from the IEC document. Both have the following four complementary parts:

I.S. EN 62305-1 General principles - provides the general principles for the protection of structures, their people, contents and electrical installations, against the damaging effects of lightning.

I.S. EN 62305-2 Risk management - details the wider considerations of lightning strikes such as danger to life, possible data loss, and cultural impacts if heritage buildings are damaged. Secondary economic implications of loss of services in the wake of lightning strikes are also analysed.

There are four types of loss to be considered in I.S. EN 62305-2

  • R1 – Loss of Human Life
  • R2 – Loss of Services to the Public
  • R3 – Loss of Cultural Heritage
  • R4 – Loss of Economic Value

I.S. EN 62305-3 Physical damage to structures and life hazard - describes the basic categories of protection from lightning according to risk, and provides detailed guidance for an engineer designing a lightning protection system.

Class of Lightning

Protection

I

II

III

IV

Faraday Cage Type

Installation (Meters)

5 X 5

10 X 10

15 X 15

20 X 20

Typical Distance of Down

Conductors (Meters)

10

10

15

20

I.S. EN 62305-4 Electrical and electronic systems within structures - provides updated information and guidance for the protection of the sensitive electronic equipment typical in modern buildings, including servers and wired networks. A zoning system is recommended to help protect such equipment from the primary and secondary effects of lightning strikes.

Note – It is perfectly acceptable to maintain or assess older lightning protection systems in line with the requirements of the latest standard; in fact, doing so should produce a more suitable solution, as it is more comprehensive in its approach than earlier standards.

Any of these methods can be used to determine placement of the air-terminations. Permitted air-terminations are:

• Rods (including masts and free-standing masts)

• Meshed conductors (on building surface or elevated)

• Catenary wires

• Natural components

Air-Terminations