DEHN HVI isolated lightning protection system
Thatched roofs are a visually pleasing option for African game lodges and other buildings, but they require significant maintenance, including protective measures against the possibility of a fire outbreak.
South Africa is a high lightning zone across vast parts of the country, with some 24 million lightning strikes per year, and direct lightning strikes can cause fires in these highly flammable roofs. Lightning strikes can also cause power surges, damaging electrical equipment and appliances in the same way as a power surge from an electrical utility source. Because they are so potentially flammable compared to other types of roof, the insurance requirements on buildings with thatched roofs can be onerous. Therefore, an insurance company requires the owner of a thatched roof building to take steps to reduce life and fire risk, through the installation of an earthing and lightning protection system.
of thatched roofs with conventional lightning masts still experience lightning damages
the increase of lightning strikes in parts of South Africa over the last years
of electrical and electronic systems are not being protected against lightning and power surges
The DEHNsure concept has received strong support from many insurance underwriters due to the technical expertise offered by DEHN Africa, which is underpinned by over 100 years of lightning protection experience, as well as our confidence in our innovative HVI lightning protection system, and the fact that we allow only trained and accredited installers to install our products.
Only DEHN products are allowed for all parts of the lightning protection system
The design must be carried out, or accepted by, DEHN Africa
DEHN Africa or our appointed inspector has to issue an acceptance certificate
The installation has to be completed by a DEHN-certified installer
DEHN’s high-voltage-resistant insulated (HVI) lightning protection system combines aesthetics and functionality in a different way of protecting thatched roofs. DEHN’s HVI technology, which has been in the global market for over 15 years, takes away the need for a separate conventional free-standing mast. It has also been proven to be very cost-effective both from an installation and maintenance point of view.
DEHN’s HVI technology has been available locally for some five years or so and offers an innovative way to protect thatched roofs from lightning strikes.
HVI masts comply to the latest SANS 62561 product standards.
Freestanding masts, which are on average 20-25 metres tall, have been used for the protection of thatched roofed structures against lightning strikes for many years, as regulated by the South African Bureau of Standards-03 (SABS-03) of 1985.
The SABS adopts the IEC 61024 series of international lightning protection standards.
SABS 03 is withdrawn and replaced by the adopted SANS 61024 series, together with the local SANS10313, which was developed to mainly address the lightning protection for thatched roofs. In this standard the conventional mast protection concept was introduced.
DEHN launched, in Germany, an innovation in external lightning protection, the high-voltage-resistant insulated (HVI) conductors. Since then, thousands of buildings and installations have been successfully equipped, making it a proven in-use technology.
First installations of HVI in South Africa: customers since then include large firms in the banking, energy, IT and tourism industries, to name but few.
Adoption of IEC 62561: Part 8 – an international product testing standard specifically developed for insulated conductors, soon to be adopted by the SABS as well. DEHN’s HVI conductors have been tested in accordance with this code.
SANS 10313: Edition 4.0 is being developed, soon to be published, which includes: a) High-voltage insulated conductors as a lightning protection solution for thatched roofs. b) A uniform installation safety report (ISR), which has been adopted by large insurance houses.
Nearby lightning strikes cause transient voltage impulses, otherwise known as surges, on the supply lines of the building. These voltage impulses can reach several thousand volts. Failure of these systems would bring business operations to a standstill, since all work processes depend on these systems. Surge arresters, together with proper bonding methods, are required to protect these electrical and electronic systems.
The first step is to consider all conductive lines leaving or entering the building, as these are more prone to lightning induced damages and as such require correctly rated surge arresters. For example, an IP66 rated outdoor DEHNpatch could be fitted on any Ethernet lines such as Wi-Fi Antennas and a DEHNgate on any coaxial connections such as satellite TV.
When applying the same concept as above, then power lines, lighting circuits and even connections for PV systems are located in the main distribution board. For this purpose, the DEHNshield comes in different versions to protect both the installation and the terminal devices, even in the case of direct lightning strikes. These terminal devices include TVs, home theatre systems and fridges, as well as alarm and video surveillance systems.
It is not only the conductive parts of the structure and the equipment installed therein that should be connected to the equipotential bonding bar, but also the earthing conductors of the power supply system and information technology equipment. For this reason, the equipotential bonding bar has a variety of connection sizes and a UV rated cover to ensure the integrity of the connections.
The DEHN HVI lightning mast is mounted directly on top of the ridge capping, making it both more effective and more aesthetically pleasing compared to conventional free-standing masts.
The mechanical support of the lightning mast is critical to ensure stability during lightning and extreme weather conditions. The supporting tube is fastened by means of specially designed mounting brackets, enabling the insulated conductors to run easily down the rafters / beams.
The DEHN HVI conductor is a high-voltage-insulated lightning carrying conductor covered with an insulating material and coated with a semi-conductive layer. This prevents uncontrolled flashovers, which results in the lightning current being contained inside the cable. This durable cable offers a high degree of flexibility during installation and requires no maintenance.
In order to safely disperse the lightning current into the ground, whilst minimising any potentially dangerous overvoltages, a single integrated earthing system is required. The earthing system is the heart of a lightning protection system and as such needs to be tested annually, but these tests can be extremely onerous, which is why an inspection box makes testing so much easier.
As you are aware, for many years now we have struggled with lightning damage on the Estate which has led us to investigate lightning protection options other than conventional lightning masts. After some investigation we came across DEHN’s HVI solution, which not only addressed the question of effectiveness but is also far more aesthetically pleasing than conventional masts.
HVI is a high quality, tested product, is easy to install, has less risk in terms of rigging and can carry more than 100 000 volts without discharging to other equipment. If it's installed properly, there is no corrosion that can take place, therefore having good connections all the time. HD (Pty) Ltd. earthing & lighting protection is very impressed about the introduction of HVI.
