Lightning is fascinating to watch but also extremely dangerous. It is an atmospheric
discharge of electricity accompanied by thunder, which typically occurs during thunderstorms,
and sometimes during volcanic eruptions or dust storms.
A lightning can travel at speeds of 220,000 km/h (140,000 mph), and can reach temperatures
approaching 30,000 °C (54,000 °F), hot enough to fuse silica sand into glass channels
known as fulgurites which are normally hollow and can extend some distance into
the ground. There are some 16 million lightning storms in the world every year.
It can damage roofs, explode brick and concrete and ignite fires. In addition to
personal physical damage, it can wreak havoc with computers, electronic equipment
and appliances. The number of homes struck by lightning every year is increasing
and losses exceed cores of rupees annually.
Technically, there is none. In general, the term "thundershower" tends to denote
a fairly weak storm with light to moderate rainfall and low levels of lightning
activity. However, there are no defined parameters that distinguish between a thundershower
and a thunderstorm. In fact, in order to avoid confusion, we in the National Weather
Service do not use the term "thundershower". If a shower is strong enough to produce
lightning, even just one single bolt, it's called a thunderstorm.
All thunderstorms go through stages of growth, development, electrification, and
dissipation. Thunderstorms often begin to develop early in the day when the sun
heats the air near the ground and pockets of warmer air start to rise in the atmosphere.
When these pockets of air reach a certain level in the atmosphere, cumulus clouds
start to form. Continued heating causes these clouds to grow vertically into the
atmosphere. These "towering cumulus" clouds may be one of the first signs of a developing
thunderstorm. The final stage of development occurs as the top of the cloud becomes
anvil-shaped.
As a thunderstorm cloud grows, precipitation forms within the cloud. A well-developed
thunderstorm cloud contains mostly small ice crystals in the upper levels of the
cloud, a mixture of small ice crystals and small hail in the middle levels of the
cloud, and a mixture of rain and melting hail in the lower levels of the cloud.
Air movements and collisions between the various types of precipitation in the middle
of the cloud cause the precipitation particles to become charged. The lighter ice
crystals become positively charged and are carried upward into the upper part of
the storm by rising air. The heavier hail becomes negatively charged and is either
suspended by the rising air or falls toward the lower part of the storm. These collisions
and air movements cause the top of the thunderstorm cloud to become positively charged
and the middle and lower part of the storm to become negatively charged.
In addition, a small positive charge develops near the bottom of the thunderstorm
cloud. The negative charge in the middle of thunderstorm cloud causes the ground
underneath to become positively charged, and the positively charged anvil causes
the ground under the anvil to become negatively charged. How
Almost all lightning will occur within 10 miles of its parent thunderstorm, but
it can strike much farther than that. Lightning detection equipment has confirmed
bolts striking almost 50 miles away, but these are very rare. Understanding the
dangers of lightning is important so that you can get to a safe place when thunderstorms
threaten. If you hear thunder even a distant rumble or a crackling aloft you are
already in danger of becoming a lightning victim.
The sound of thunder travels about a mile every 5 seconds. If you count the seconds
between the flash of lightning and the crack of thunder and divided by 5, you get
the number of miles away from you (10 seconds is 2 miles).
There is no safe place outside when thunderstorms are in the area. If you hear thunder,
you are likely within striking distance of the storm. Just remember, When Thunder
Roars, Go Indoors! Too many people wait far too long to get to a safe place when
thunderstorms approach. Unfortunately, these delayed actions lead to many of the
lightning deaths and injuries.
The best way to protect you from lightning is to avoid the threat. You simply don’t
want to be caught outside in a storm. Have a lightning safety plan, and cancel or
postpone activities early if thunderstorms are expected. Monitor weather conditions
and get to a safe place before the weather becomes threatening. Substantial buildings
and hard-topped vehicles are safe options. Rain shelters, small sheds, and open
vehicles are not safe.
A safe shelter from lightning is either a substantial building or a enclosed metal
vehicle. A safe building is one that is fully enclosed with a roof, walls and floor,
and has plumbing or wiring. Examples include a home, school, church, hotel, office
building or shopping center. Once inside, stay away from showers, sinks, bath tubs,
and electronic equipment such as stoves, radios, corded telephones and computers.
A safe vehicle is any fully enclosed metaltopped vehicle such as a hard-topped car,
minivan, bus, truck, etc. While inside a safe vehicle, do not use electronic devices
such as radio communications during a thunderstorm. If you drive into a thunderstorm,
slow down and use extra caution. If possible, pull off the road into a safe area.
Do not leave the vehicle during a thunderstorm.
The earliest literature available that proposes protection from lightning starts
in 1752 with Benjamin Franklin. Franklin’s original idea was to use a sharp point
to draw charges from the cloud to discharge it and thus prevent lightning. Early
experiments by Franklin in electrostatics had him arrive at this conclusion. By
placing objects with different geometries (sharp and blunt) near a charged object,
Franklin found that differing amounts of charge were drawn from the original charged
object. (Later researchers would come to understand that electrostatic lines of
force concentrate at sharp points, theoretically verifying his electrostatic experiments.)
He consequently published the first instruction for protection from lightning.
Yes. Lightning protection has been saving homes and other structures for well over
100 years. The basic science of lightning protection goes back to the days of Ben
Franklin. The latest codes and regulations NFC 17-102 780 incorporate over 200 years
of scientific study and provide the only way to reliably and consistently protect
your building from lightning damage.
An entire lightning strike employs both upward and downward moving forces. However,
the return stroke of a lightning bolt travels from the ground into the cloud and
accounts for more that 99% of the luminosity of a lightning strike. What we see
as lightning does indeed travel from the ground into the cloud.
A lightning protection system protects your home, office, commercial building, or
other structure from lightning damage. Lightning damage can include complete or
partial loss of a building and its contents due to fire and structural damage. Lightning
damage can also include damage to computers, electronics, appliances, electric fences,
satellite dishes, telephone systems, hot tubs, and more.
Good lightning protection is solid, straightforward science. A lightning protection
system performs a simple but crucial task. Lightning contains millions of volts
of electricity. When lightning strikes your building, your lightning protection
system provides a specified, highlyefficient path on which the millions of volts
of electricity can travel safely to the ground. On a building without lightning
protection, those same millions of volts of electricity still have to get to the
ground. Lightning will use your electrical wiring, your telephone or cable wiring,
structural elements of your building, or anything else it can find as a “path to
ground”. None of these building elements is designed to safely carry this amount
of electricity. The result is a build-up of resistance, which leads to fire and
explosive damage to your building. Your lightning protection system gives the lightning
exactly what it needs – an easy and efficient path to ground. The result is usually
no damage to your building. In fact, if you are not in the building when lightning
strikes, you may not even know the building was struck.
Lightning is the visible discharge of static electricity within a cloud, between
clouds, or between tile earth and a cloud. Scientists still do not fully understand
what causes lightning, but most experts believe that different kinds of ice interact
in a cloud. Updrafts in the clouds separate charges so that positive charges moves
end up at the top of the cloud while negative flow to the bottom. When the negative
charge moves down, a "pilot leader" forms. 'This leader rushes toward the earth
in 150-foot discrete steps, ionizing a path in the air. 'The final breakdown generally
occurs to a high object the major part of the lightning discharge current is then
carried in the return stroke which flows along the ionized path. A lighting protection
system provides a means by which this discharge may enter or leave earth without
passing through and damaging non-conducting parts of a structure, such as those
made of wood, brick, and tile of concrete. A lightning protection system does not
prevent lightning from striking; it provides a means for controlling it and preventing
damage by providing a low resistance path for the discharge of lightning energy.
The air terminal is a device for lightning protection with a spherical metal part
fixed to the top. This sphere is insulated from the rod by a ring made from a material
with very high electrical insulation properties. When a storm comes, the external
electrode (sphere) charges under the influence of the electric field until the potential
reaches a critical value from which a spark appears between the exterior electrode
and the tip of the central electrode. The tip enables plasma to be created close
by the tip. The plasma, in association with the intense electric field created close
by the tip, constitutes the first stage of development of an upward leader. The
spark produced at the top of the air terminal will initiate the advance of the discharge,
engendering an upward leader moving in the direction of the downward leader.
No, it does not require any power supply or power back-up. STAR ESE terminals do
not work with any power back-up. It is very clearly declared/mentioned in their
technical brochure. It works just based on the change in the atmosphere charges.
The moment the charges in the atmosphere exceeds the threshold level (i.e. spark
over voltage of the ESE terminal - the potential different between the blades and
base unit), the charges are emitted outside in the cloud thus attracting the lightning.
We suggest only maximum height of 5 meter from the roof height and level 3 protection
of 107 meters radius. Mast height is mentioned from 2 to 20 meters. Increase in
protection radius is very good from 2 to 5 meters. After 5 meters, there is no big
gain in protection radius just by increasing the mast height. This is decide as
per the NF C 17 102 formula (i.e. as per National French Commission standard).
The conventional lightning protection system forms a kind of metal grid on top and
around the building. Here the copper/GI strips form a kind of grid with each other
and at every 3 to 5 meters a sharp metal rod of about 1 foot is placed. Then after
some distance interval the down conductors (strip) is placed and then to earth pits.
By doing this the maintenance of all this put together becomes a costly & wastage
of time. In some conditions, however the active lightning system is the only possible
method to protect from direct lightning strokes. Due to the arguments mentioned
above, it is recommend using the lightning protection system whenever the conventional
solution is inconvenient or when the former is more preferable to the latter as
in the case of the efficient protection of architect.
This is a seemingly simple question, but there is no single answer that fits everyone.
Good factors are the Geographical location and annual climatology.
There are no safe places outdoors during a lightning storm. Avoid open fields, the
top of a hill or a ridge top. Keep your self away from tall, isolated trees or other
tall objects. If you are in a forest, stay near a lower stand of trees. If you are
camping in an open area, set up camp in a valley, ravine or other low area. Stay
away from water, wet items such as ropes and metal objects, such as fences and poles.
Water and metal are excellent conductors of electricity. The current from a lightning
flash will easily travel for long distances.
YES! If a bolt strikes your house or a nearby power line, it can travel into your
house through the plumbing or the electric wiring! If you are using any electrical
appliances or plumbing fixtures (including telephones and computers), and a storm
is overhead, you are putting yourself at risk. About 4-5% of people struck by lightning
are struck while talking on a corded telephone.
Yes. These are safe to use because there is no direct path between you and the lightning.
Avoid using a corded telephone unless it's an emergency.
Yes. In fact, more lightning protection systems are installed now than ever before.
Today’s lightning protection systems are inconspicuous. Since buildings today are
equipped with many sensitive electronic systems, planners tend to include lightning
protection systems not only to protect the structure but also to help protect the
electronic systems and to keep the buildings up and running.
Wrong. In fact, a building or area that has been hit can indicate that the area
is a “hot zone” for lightning strikes. Some buildings get hit so often that we install
a “counter” as part of the lightning protection system to keep track of the lightning
strikes. The Empire State Building(USA) gets struck by lightning, on average, over
100 times a year, yet suffers no damage due to its lightning protection system.
No. The electrical ground installed by your electrician is there to protect the
internal workings of the electrical system in your building. It is not at all designed
to protect you from lightning damage.
SPD’s are installed where utilities such as electrical service, telephone, and cable
or satellite enter your building. When a nearby or distant utility pole or transfer
station gets struck by lightning, damaging surges can come down the wires into your
building. SPD stop these surges before they start electrical fires and before they
cause damage to your computers, electronics, and appliances. So, SPD means your
lightning protection system is effective even when your building does not suffer
a direct lightning strike.
Lightning protection can be installed at any time. It is better and advisable when
new construction is taking place.
Your lightning protection system is designed to last for the life of your building.
If you make structural changes or additions, you should have your system checked
and updated if needed.
Your lightning protection system is designed to last for the life of your building.
If you make structural changes or additions, you should have your system checked
and updated if needed.
The human body does not store electricity. It is perfectly safe to touch a lightning
victim to give them first aid. This is the most chilling of lightning Myths. Imagine
if someone died because people fail to give first aid (CPR).
The structural steel of a building does conduct lightning, but you need a lightning
protection system to provide the necessary interconnections to make sure that the
lightning is able to pass harmlessly through the building. Without the lightning
protection system, when a building is struck the lightning attempts to find a path
to ground. If there are not enough interconnections providing a continuous path
for the lightning to follow, there will be arcing or side-flashing. The lightning
will also travel on other mechanical systems in a building such as the electrical
or HVAC systems. The lightning current jumping from object to object within a building
is dangerous and has been known to cause fires, explosions, etc.
Any structure is a good candidate for lightning protection. All buildings are subject
to lightning damage. A structures use and contents are as much a consideration as
location and construction when determining lightning risk. It is commonplace for
lightning protection systems to be installed on schools, hospitals, health care
facilities, airports, shopping centers, office buildings, manufacturing facilities,
etc.
Cost varies greatly depending on the location of the structure, its size, its construction,
the complexity of the roof-line and the ground conditions. Costs are lower when
the system is designed and installed during construction. Retrofitting a system,
is very common, but tends to be slightly more expensive. In comparison with other
building systems, such as security or plumbing, the lightning protection is usually
less costly.