Industrials

Importance Of Lightning Protection System In Buildings

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<p>Necessity of lightning protection system:</p><ul><li>Lightning is one of nature&rsquo;s most powerful &amp; destructive phenomena.</li><li>It contains a huge amount of energy (several thousands of Amps)</li><li>It is a short duration ( up to 200 &micro;sec ) but is a real cause of damage &amp; destruction</li><li>Primary effect- Buildings damaged, trees blown, personal injuries and even death</li><li>Secondary effect- Transient overvoltage- damage to electronic system</li><li>It can also cause fire, explosion, chemical release or mechanical disruption within or around a bldg.</li></ul><p>&nbsp;</p><p>Lightning Protection System (LPS)</p><ul><li>The lightning rod (Rod is earthed by one or more conductors)</li><li>The lightning rod with taut wires (stretched above structure)</li><li>Lightning conductor with meshed cage/Faraday cage (numerous down conductors &amp; tape&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; symmetrically placed)</li></ul><p>&nbsp;</p><p>&nbsp;<img style="float: left;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+1.png" /></p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+2+.png" /> &nbsp;</p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+3+.png" /></p><p>Standards:</p><ul><li>BS 6651</li><li>NFPA 780</li><li>BS-EN/IEC 62305</li><li>In Aug. 2008, BS 6651 has been withdrawn</li><li>Now IEC 62305 &amp; NFPA 780 are the recognised standards for LPS</li></ul><p>&nbsp;</p><p>Elements of a Lightning Protection System (LPS)</p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+4.png" /></p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</p><ol><li>Air Termination System (Arrestor)</li></ol><ul><li>Arranged at or along upper points of a roof</li><li>Used to capture lightning current</li><li>Dissipate it harmlessly to earth</li><li>Material- Copper, Aluminium</li><li>It consists of base, air rods &amp; multiple points</li><li>25*6 mm Al tape on surface interconnected through clips and clamps (fig. 1 to 3)</li><li>Clamps will ensure a low resistance, corrosion-resistant connection between air termination and down conductors.</li></ul><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+5+.png" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;</p><p>&nbsp;</p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+6+.png" /></p><p>&nbsp;</p><ol start="2"><li>Down Conductors ( Steel rebar )</li></ol><ul><li>Provides direct route from arrestor to earth</li><li>Greater the no, better the current sharing</li><li>Placed in concrete column (during civil work) or can be bare conductor</li><li>Either copper or steel bars are used</li><li>2 reinforcement bars of 25 mm dia. Placed in the centre of the column along the periphery</li><li>Rebar to rebar connection-20D to ensure secure connection &amp; proper bonding</li></ul><p>&nbsp;</p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/mansih+7.png" /></p><p>&nbsp;</p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+8.png" /></p><p><img style="float: left;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+9.png" /></p><p>&nbsp; &nbsp;<img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+10.png" /> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</p><p>&nbsp;</p><p>&nbsp;&nbsp;&nbsp; &nbsp;Fig 1 shows Test links- Periodic disconnection &amp; testing of the earth termination system</p><p>&nbsp;</p><ol start="3"><li>Earth Termination system ( Earthing )</li></ol><ul><li>Vital for the dispersion of current safely &amp; effectively</li><li>It should have low electrical resistance &amp; good corrosion resistance</li><li>It consists of earth electrodes, plate, mat, pits, Bars, earth points, bonds &amp; clamps</li></ul><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+11.png" /></p><p>&nbsp;</p><p>&nbsp;</p><p>Earth electrode arrangement should be as mentioned below :</p><p>Type A&nbsp;&nbsp;</p><p><img src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+12.png" /></p><p>Type B</p><p><img src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+13.png" /></p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p><ol start="4"><li>Lightning Equipotential Bonding</li></ol><ul><li>Interconnection of all metallic parts e.g. cable armouring, gas, water piping</li><li>So in the event of lightning, no metallic part is at a different voltage level w.r.t. one another</li><li>Should be near to Main LT / HT Panel &amp; closely connected to earth with short length conductor</li></ul><p>&nbsp;</p><p><img style="display: block; margin-left: auto; margin-right: auto;" src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+14.png" /></p><p>Where to provide earth connection?</p><ul><li>Body Earthing</li><li>Neutral grounding ( only at source end &ndash; transformer &amp; Diesel generator )</li><li>Earthing for lifts</li></ul><p>Non-conventional methods of earthing are pile earthing (cost-saving) &amp; Ashlok chemical earthing.</p><p>&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<img src="https://kradminasset.s3.ap-south-1.amazonaws.com/ExpertViews/manish+15.png" /></p><p style="text-align: center;">Pile earthing chambers for body earthing.</p>
KR Expert - Manish Kothawala