How a Lightning Protection System by BjManindarKumar


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									How a Lightning Protection System Works:

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, 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.

                                                FIG. 3 Lightning protection system for a
                                                dwelling: 1) air terminals spaced 20 feet apart
                                                along ridges and within two feet of ridge ends;
                                                2) down conductors; 3) minimum of two
                                                groundings at least 10-feet deep; 4) roof
                                                projections such as weather vanes connected to
                                                system; 5) air terminal located within two feet
                                                of outside corners of chimney; 6) dormers
                                                protected; 7) antenna mast connected to roof
                                                conductor:- 8) connect gutters or other
                                                grounded metals as required; 9) surge arrester
                                                installed at service panel to protect appliances;
                                                10) transient voltage surge suppressors installed
                                                in receptacles to which computers and other
                                                electronic equipment are connected.

                                                FIG. 4 Lightning protection system
commercial/industrial installation 1) air
terminals spaced 20 feet apart around the
perimeter of the building; 2) down
conductors; 3) ground rods at least 10-feet
deep; 4) art handling units bonded to
system (may be in need of air terminals
mounted on unit); 5) air terminals
mounted within two feet of outside corner;
6) mid-roof conductor and air terminals at
maximum 50-foot spacing; 7) grounded
metal bodies bonded into system; 8) surge
arresters installed at main electrical
panels; 9) transient voltage surge
suppressors installed in receptacles to
protect computers and other office equipment.

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