Page 68 - E24 Electrical Notebook

64 - Lightning & Transient Protection

Furse Total Solutions Service

Total Solution to Lightning Protection, Earthing & Design & Support Services FurseWELD
Transient Overvoltage Protection Requirements
Surge Protection Earthing
From design advice to innovative, solution-oriented products, Furse has
the expertise, experience and excellence to provide a Total Solution to your Electronic Systems Protection
individual lightning protection, transient overvoltage and earthing problems.
BS 6651 had an informative annex C giving the reader recommendations
Lightning Protection Standards on the implementation of Surge Protection Devices (SPDs). BS EN 62305
now has transient overvoltage protection as an integral part of the
BS EN 62305 replaced BS 6651 in 2008, and, following on from the IEC standard (BS EN 62305-4), governed by the single risk assessment of
(World) and CENELEC (European) versions of IEC/EN 62305, is the BS EN 62305-2. Where required by BS EN 62305, SPDs shall be selected
recognized standard for lightning protection. and installed in accordance with the IET Wiring Regulations (BS
7671:2008 +A1:2011, Section 534).
BS EN 62305 is a four part standard consisting of General principles;
Risk management; Physical damage to structures and life hazard; and Even with the best available structural lightning protection, the electrical
Electrical and electronic systems within structures. Additionally, it and electronic contents of a building are at risk from the secondary effects
includes the requirements of the BS EN 62561 series of standards, which of lightning – transient overvoltages. Lightning activity can create
is the ratified European standard relating to the capabilities of lightning sub-millisecond transient overvoltages of up to 6,000 V on power, data,
protection components. signal and telephone lines. Transients destroy, damage or degrade the
electronic components of the equipment through which they pass on their
BS EN 62305 Part 1 is an introduction to the other parts of the standard route to earth. Transients can also occur on mains power supplies within
and essentially describes how to design a Lightning Protection System the building through electrical switching events. Any piece of equipment
(LPS) in accordance with the accompanying parts of the standard. incorporating electronic components is at risk: from computers and PBX
to fire alarms and even Uninterruptible Power Supplies.
BS EN 62305 Part 2 risk management is a very detailed approach to the
risk of lightning inflicted damage to structures, their contents (electronic To prevent transient damage, SPDs should be fitted on all metallic power,
equipment) and living beings. It identifies different risk components that data communication, signal and telephone lines where they enter or leave
collectively are compared to a tolerable risk. It is a very long-winded a building. The Furse ESP range includes SPDs for most applications,
process when carrying out the assessment long hand. A computer including mains power, data or signal lines, telephone lines, CCTV / CATV
program is commercially available from Furse to considerably reduce the video cables, coaxial RF lines and Ethernet networks.
time to implement the risk procedure.
Technical Assistance
BS EN 62305 Part 3 relates directly to the major part of BS 6651. It differs
from BS 6651 in as much that it has four classes or protection levels of Detailed technical guidance is available from Furse engineers in
Lightning Protection System (LPS), as opposed to the basic two (ordinary Nottingham, and our field-based engineers can provide site surveys and
and high-risk) levels in BS 6651. protection proposals.

BS EN 62305 Part 4 covers the protection of electrical and electronic
systems housed within structures. This part essentially embodies what
annex C in BS 6651 detailed, but with a new zonal approach referred to as
Lightning Protection Zones (LPZ). 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.

To assist with customer concerns, we offer a design and advisory service
for lightning protection to IEC/BS EN 62305.

Structural Lightning Protection

It is vital that buildings are designed and equipped with a lightning
protection system that will ensure the safety of the structure, and its
occupants. Given the importance of bonding and proper connection of
the components of the Lightning Protection System (LPS), just one faulty
or poor quality component can lead to costly damage, even fatalities.

Furse lightning protection products are designed and manufactured to
the highest standards. Primary in our range are our conductors – in flat
tape, solid circular and stranded format, copper and aluminium, many of
which can be PVC coated for greater aesthetic appeal.

Furse also offer a large range of air terminals, fittings, bonds, clamps and
lightning current / equipotential bonding Surge Protection Devices (SPDs).
In accordance with BS EN 62305, these SPDs are required where direct
connection with bonding conductors is not suitable – for example metallic
power and telecommunication lines.

Effective Earthing

The dangers posed to both life and equipment by poor earthing make
effective earthing essential. Given the complexity of national and
international standards in earthing system design, material specification
and installation, it makes sense to talk to Furse.

Furse design and model earthing electrode systems in compliance with
BS 7430, IEEE standard 80, BS EN 50522, ENA TS 41-24 and other
accepted standards. The comprehensive Furse range of earthing
equipment includes: solid copper, stainless steel and copperbond earth
rods and accessories; high copper alloy bonds and clamps; earth pits,
solid copper plates, lattice mats, earth rod seals and the FurseWELD
exothermic welding system.

ABB Furse Tel : +44 (0) 115 964 3700
Wilford Road Fax : +44 (0) 115 986 0071
Nottingham E-Mail : enquiry@furse.com
NG2 1EB Website : www.furse.com