improvised lightening protection system for indegenous homes

8/8/2019 Improvised Lightening Protection System for Indegenous Homes

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Improvised Lightning Protection System for

Indigenous Homes and Makeshift HutsZ. A. Hartono and I. Robiah

Lightning Research Pte. Ltd., Malaysia

E-mail: [email protected], [email protected]

Abstract: Lightning strikes to indigenous homes and makeshift huts in rural and poor

urban areas have resulted in many casualties in developing and third world countries. Due to

the small size of these structures and the large number of people that occupy them, the

reported incidences have resulted in high numbers of casualties. This casualty rate can be

significantly reduced if a crude form of lightning protection system had been installed.

Keywords: Lightning protection system, air termination, down conductor, ground

termination, ground potential rise.

1. Introduction

Lightning strikes to indigenous homes and makeshift

huts have resulted in a high number of casualties in Asian,

African and South American countries annually. These

incidences occurred in fragile structures that were made of

materials such as wood, bamboo, straw, stones and earth.

The victims were injured or killed either by direct

lightning strikes or by the resultant fires caused to the

structures. In the latter cases, some of the victims were

believed to have been killed by the resultant fire due to

their inability to escape the burning site. In some of the

reported cases, whole families were killed in this way.

The casualties in the above incidences could be reduced

if an improvised lightning protection system (ILPS) had

been installed. The proposed ILPS consists of conductors

that are positioned on the indigenous building according to

the current lightning protection standards. However, in

order that it is very affordable to the indigenous

population, it is made from materials that do not fully

comply with the standards in terms of metallic compositionor dimension.

The presence of the proposed ILPS could channel the

lightning flash away from the occupants and reduce the

chances of the occupants being struck directly by the

lightning current. The ILPS could also create an equi-

potential voltage rise that will prevent some or all of the

occupants from being seriously injured and hence be able

to flee the site.

2. Lightning incidents in Malaysia

The idea for the proposed ILPS came about from the

reported casualties from two direct lightning strike

incidents and investigations carried out on lightning strikes

to TV antenna systems.

In the first incident, one person was killed and more

than a hundred other people were slightly injured when the

building they were in was struck by lightning. The

lightning current had apparently flowed down one of the

pillars in the building and the person who was leaning

against the pillar was killed instantly. The remaining

victims were sitting on the floor when the lightning strike

occurred and all of them suffered leg paralysis immediatelyafter the incident. Most of them were temporarily

paralysed in the legs and were unable to move until help

arrived.

In the second incident, two persons were killed and

about two dozen others were injured when lightning struck

their campsite on top of a hill. The two victims who were

killed were inside a tent that was erected beside a small

tree that was struck by lightning. The dead victims were

those who were closest to the tree while sitting inside the

tent. The others who were inside the same tent were

seriously injured while those who were inside the other

tents escaped serious injuries. The dead and seriously

injured victims all suffered bodily burns from the lightning

strike. Many of the injured victims were unable to move

until help arrived several hours later.

In the two incidents described above, it was fortunate

that the lightning strike did not result in a fire to the

building or tents. Otherwise, the number of dead victims

could have been a lot higher.

In investigations carried out on lightning incidents to TV

antenna of several homes, it was found that the lightning

current had entered these homes but did not cause any

injuries to the occupants. The investigations showed that in

some cases, the upper sections of the antennae coaxial

cable were completely burnt and left behind burn marks on

the walls.


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Although the lightning current is large enough to burn

parts of the antenna cables, some of the TV sets were

reported to be completely undamaged. This led to the

conclusion that the lightning current may have beendiverted into the buildings steel reinforcement bars which

were located inside the walls.

From the above investigations, it is apparent that a crude

form of lightning protection system, an ILPS, which does

not fully comply with the current lightning protection

standards may be able to reduce the number of casualties

in lightning incidents that affect homes and buildings in

rural and under-privileged areas.

3. Indigenous homes and makeshift shelters

These buildings are those constructed in rural areas bythe local and native population using locally available

building materials. Examples of these buildings are the

attap houses in Asia, the long houses in Borneo, the

rondavels in Africa and similar native buildings in South

America. These buildings are made of locally available

construction materials such as tall grass, leaves, coconut

fronds (attap), wood, bamboo, mud or rocks.

In urban or sub-urban areas, makeshift shelters are built

by mainly migrant workers as their homes or business

premises. The materials may also include corrugated metal

sheets for the roof or walls.

In some cases, these structures were built in areas that

are partially or completely devoid of tall vegetation (such

as the African savannah, the Central Asian steppes or the

paddy fields) and hence they are completely exposed to

direct lightning strikes.

Photo credit: Guardian, UK

Some of these homes are also located on hill tops and

sides, thus increasing their risk to direct lightning strikes.

Hence, it is not surprising that a direct lightning strike to

one of these dwellings have resulted in a high number of

casualties.

Photo credit: Guardian, UK

4. ILPS general description

Realizing the above situation, it is proposed that the

ILPS be widely implemented for the safety of the poor and

indigenous population. The primary objective of the ILPS

is to save as many lives as possible. The proposed ILPS

can divert the lightning current away from the occupants of

the hut and create a region of uniform high voltage

potential across the floor of the building. In this way, the

occupants of the hut will not be struck directly by lightning

and they will not be paralysed and they can escape from

their homes if it catches fire.

In order to be very affordable, the ILPS should be madefrom easily available local materials such as domestic

electric cables or similar metallic wires (eg. galvanized

iron wire). Even discarded domestic electric cables should

be recycled to be used for free as an ILPS.

The basic ILPS design and construction should also be

simple for the user to understand and implement with

minimal instruction, tools and supervision. The

construction of the ILPS should also not have any adverse

impact on the already limited resources of the local

environment, such as the need to cut down trees in order to

provide wood for the construction of the system.

5. ILPS basic designThe basic design of the ILTS consists of (at least) a

single combined air termination and down conductor

segment which is connected to a buried ring ground

conductor. The air termination and down conductor

segment can follow the general outline of the roof and wall

of the building while the buried ring ground can follow the

plan of the building.

The example show below is for a building with a

circular shaped wall and a cone shaped roof. The solid

lines represent the ILPS while the dotted lines represent the

outline of the building.

E


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Side view:

Plan view:

6. ILPS basic constructionThe air terminal and down conductor segment (eg. a

length of bare electric cable) is laid on the roof of the

building and secured in place by tying it to the roof with

any available material such as twine or rope. This sectionof the ILPS should be diagonally placed across the roof.

The ring ground conductor which is similar above is

buried a few centimetres in the ground along the perimeter

of the building. Both ends of the conductor are joined

together by twisting the strands around each other.

The lower ends of the down conductor are similarly

twisted onto the ring ground conductor before the latter is

buried in soil.

Alternatively, the conductor ends can be joined together

using simple and cheap termination blocks. However, the

absence of this and other basic devices should not

discourage the installation of the ILPS.

7. ILPS anticipated performanceDuring a lightning strike to the ILPS, the lightning

current is channelled along the down conductor and into

the ring ground. The lightning current may ignite the roof

and wall of the building if they are made of combustible

materials such as dry straw and leaves. However, thelightning current may not strike any of the occupants who

may be standing, sitting or lying down inside the building.

As the lightning enters the ring ground system, it will

create an uniform voltage rise across the building. This

uniform voltage rise may not cause severe muscular

paralysis to the occupants as described earlier in the

Malaysian incidents. In this scenario, some of the

uninjured occupants may be able to assist those who may

be injured.

If a fire breaks out, the uninjured occupants may assist

the victims to flee the burning building. In this way, the

number of casualties may be kept to a minimum.

8. ConclusionFrom studies conducted on incidences of lightning

strikes in Malaysia, it was found that many victims of

lightning strikes in indigenous homes and makeshift huts

around the world could have been killed by the resultant

fires and not by the lightning strikes themselves. Hence,

the fatal victims of these incidences could be minimized if

their injuries can be minimized so that they are still mobile.

The ILPS is an interim solution to the problem of high

lightning casualties reported among rural and indigenous

populations of the developing and third world. This

problem is expected to increase in the near future as the

population in these areas continues to grow.

The primary purpose of the ILPS is to reduce the high

number of deaths from lightning strikes that were reported

each year in the media. Most of these deaths is believed to

come from the resultant fire and not from the lightning

strikes themselves. The ILPS is not proposed to protect

indigenous homes and makeshift huts from being damaged

or lost as a result of lightning strikes.

The high cost of installing a fully compliant lightning

protection system should not become a stumbling block in

providing lightning protection to people who live in the

high flash density zones of Africa, Asia and South

America.

Air termination

Downconductor

Ring ground

improvised lightening protection system for indegenous homes

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