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Lightning Protection Human Protection Building protection.

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Presentation on theme: "Lightning Protection Human Protection Building protection."— Presentation transcript:

1 Lightning Protection Human Protection Building protection

2 Under thunderstorm conditions never be the tallest object in the area If you are happened to be the first object to send the answering leader you will be struck by lightning

3 Do not perform the following acts under thunderstorm conditions

4 Hiking

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7 Riding cycles on open spaces

8 Staying on a Playground Beach Open road Roof Top or Any Other Open Space

9 Sailing an open boat

10 Repairing Telecommunication or Power lines

11 Working on Cranes and other high elevated vehicles

12 Working on agricultural fields

13 Using elevated metal objects

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21 Caught up outdoors in an intense thunder storm, it is very dangerous to get shelter under a tree The large current that flows along the trunk of a tree as a result of a lightning strike may decide to jump into your head or hand and reach the ground through your body when you stand nearby. This is termed a side flash

22 Getting a side flash If you are in a building which is not protected against lightning under severe lightning conditions keep a distance of at least 2m away from the walls The highest number of outdoor lightning accidents occur as people stay underneath large trees

23 Step Potential Then a part of the lightning current will flow through your body which may paralyze you When lightning strikes a place a potential gradient develops away from the point of strike If a person keep his body radial to the potential gradient then he will be subjected to a potential difference

24 Lightning Flash Current {`r`v Ground Step Voltage pQyvr vQxv an\wry

25 Situation just after the strike Situation just before the strike Stepped leader Connecting leader

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28 Animals are most often killed by step potential Animals are most often killed by step potential Lightning killed 504 sheep when a stroke hit the ground in this rocky pasture in Utah. A stroke to high-resistance soil can produce exceptionally high voltage in the ground and spread over an unusually large area.

29 Therefore according to the international standards under heavy thunder storm conditions you have to squat on the ground keeping the feet close together an cover your ears with hands Therefore according to the international standards under heavy thunder storm conditions you have to squat on the ground keeping the feet close together an cover your ears with hands

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31 Caught up outdoors in an intense lightning storm, the worst position is to lie down flat If you lie down flat in a thunderstorm a lightning that strikes ground nearby may send a current through the soil, which may enter your body from head and leave from the feet thus damaging many of the vital internal organs. The best position to be in such a condition is to squat down on your feet and to rest the head on the knees. Never sleep on floor

32 Touch potential When you are touching an object which will be subjected to a lightning strike a part of the current may flow across your body

33 Therefore do not touch metallic masts flag poles fences etc. during lightning periods

34 Rubber boots or plastic rain coats will not give you any protection against lightning

35 The service lines such as power and communication cables extend many many kilometers over open lands thus they are exposed very much to lightning The service lines such as power and communication cables extend many many kilometers over open lands thus they are exposed very much to lightning

36 These lightning currents may enter near by utilities destroying all the equipment connected to the service lines irrespective of the fact whether they switched on or off Under such circumstances a person using the service (eg. Telephone) may be severely injured (even dead)

37 It is a high risk to repair electrical networks (house wiring etc.) during thunderstorm periods Similar to telephones, a large current may propagate through a power cable in the event of a lightning strike. This current may reach a person who repairs the network even if the main switch is off.

38 Is it safe to be inside a car when lightning striking around? YES In a sturdy metallic object such as a car, you will get the Faraday Cage protection Keep your body away from the metallic frame. Keep your hands on the lap. Do not use hand- free phones

39 But be careful !! Some modern cars are made with fiber glass body parts. Some cars have removable plastic roofing Both of these types are not very good for lightning protection

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45 A person struck by lightning does not retain any charge. Thus please attend to him and give the first aid as soon as possible 90% of the lightning victims can be saved from death if first aid is given in time

46 In 1998, in a provincial football match played in Congo, 11 players were killed by a single lightning struck on the ground. In 2001, in Sri Lanka, 5 women were killed by a lightning strike as they were getting the shelter of a big tree. In 2005, in Bangladesh 8 people were killed when lightning struck a tent with metal roof Thus under lightning conditions keep at least 2m between two people One lightning Killing many people

47 Lightning Striking a Person with Wet Clothes If you are lightning struck while wearing wet clothes, the lightning current may decide to take an external path as the resistance of wet clothes is less. Thus you may be saved only with few skin burns.

48 What else I can do when lightning strikes around? Avoid taking a bath either indoor or outdoor Do not carry metal objects such as agricultural tools, back packs, umbrellas with metal tips etc. Wet clothes are better than dry clothes If you are in a group, spread out. Keep a distance of about 2m in between two people

49 Are there areas with high lightning density Yes! For an example, in Sri Lanka there are small pockets of areas which are having acute lightning related problems. Reason? Nobody Knows

50 Benjamin Franklin

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52 Question?


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