Lightning protec-
tion class
Protective angle for air-termination
rods length
I 70°
II 72°
III 76°
IV 79°
Table 2. The areas bordered the horizontal plane
(roof surface) and the areas enclosed the cone
sheath can considered protected areas. building part or
device) must fitted with one several air-termina-
tion rods such way that the structure fits fully un-
derneath cone sheath formed the tips the air-
termination rods and whose top angle taken from
the table. You can find
the protective angle (α) the table for the most com-
mon air-termination rods length.1
2
3
α 4
5
Protective angle
LPZ 0A
: Danger posed direct lightning strikes
LPZ 0B
: Protected from direct lightning strikes but risk
h1
: Air-termination rod height
rZ
: Radius the protected area
Z: Height the protected area
Protected area air-termination rod calculated with the simplified protective angle method
The protective angle (α) for air-termination rods varies
according lightning protection class. (Table
2.g.2)
The structure protected (e.
Should the height the roof object protected
be known, then the formula:
rz=(h1 –z)×tan (α)
can used determine the protection area the
air-termination rod formula conversion can be
used determine the required air-termination rod
length.2: Protective angle based lightning protection
class according IEC 62305-3 for air-termination rods
up length
TBS
Blitzschutz-Leitfaden
2018
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en
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2020/01/10
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2020/01/10
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64
Chapter The external lightning protection system
