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The Equivalent Collection Area of Structure
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Ae= L.W+6.H.(L+W)+9.P.H2
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L= Lenght (M)
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W= Width (M)
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H= Height (M)
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Expended Lightning Frequency
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Nd= Ng.Ae.C1.10-6
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(Ng) = 0.04• Nk 1.25
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Accepted Lightning Frequency
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Nk ; Annual Average Thunder Days Number
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Accepted Lightning Frequency
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C=C2.C3.C4.C5
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Nc=5,5.10-3/C
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C1=1 C2=0.5 C3=1 C4=1 C5=5 C=2.5
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Nd ≤ Nc Optional Protection
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Nd > Nc Protection Required
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Efficiency
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E>0.98 Level 1 + Add
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0.95<E<0.98 Level 1
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0.90<E<0.95 Level 2
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0.80<E<0.90 Level 3
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E<0 Level 4
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