iec 61024-1-1

LIGHTNING RISK ASSESSEMNT (IEC 61024-1-1) Nd - Expected direct lightning strike at the structure Nc - Acceptable damage frequency Ng - Lightning flash density per km2 at the area Ae - Structures collective area (m2) L/W/H - Length / Width / Height of the structure Td - Days of thunderstorms at the area C1 - Relative situation of the structure index C2 - Structure coefficient index C3 - Structure content index C4 - Structure occupancy index C5 - Lighting consequence index C6 - Fast resque index E - Efficiensy Relative situation of the structure

C1

Structure located in a area with structures or trees of the same high or higher

0,25

Stracture surrounded by smaller structure Isolated structures: no others structures at less than a 3H distance Isolated structure on the hill top or headland

0,5 1 2

Structure coefficient index, C2 Structure Metal Standard Flammable

Kind of roof Standard 1 1 2,5

Metal 0,5 1 2

Flammable 2 2,5 3

Structure content index No value and no flammable Standard value or normally flammable High value or particularly flammable Exceptional value, irreplaceable or highly flammable, explosive

C3 0,5 1 2 3

Structure occupancy Unoccupied Normally occupied Very occupied Difficult evacuation or panic risk

C4 0,5 1 2 3

Lightning consequence Service continuity not required, without consequences on the enviroment Industrial and commercial service continuity required, without consequences on the enviroment Critical service continuity required, without consequences on the enviroment Sevier financial damage Consequences on the enviroment Fast resque

Level of protection Level Ι and extra measures Level Ι Level ΙΙ Level ΙΙΙ Level ΙV No protection requiried

Nd=Ng x Ae x C1 x 10-6 Ng = 0,04 x Td1,25 ≈ Td/10 Ae= L x W + 6 x H x (L+W) + 9 x π x H2 or Ae = π x 9 x H2 Νc = 5,5 / (C x 103) C= C2 x C3 x C4 x C5 x C6 Ε=1-(Νc/Νd)

1 3 5 8 10 C6 1 5

Fast resque response Slow resque response Efficiensy (Ε) Ε>0,98 0,95 < Ε ≤ 0,98 0,90 < Ε ≤ 0,95 0,80 < Ε ≤ 0,90 0 < Ε ≤ 0,8 Ε