Lightning protec-
tion class
Protective angle for air-termination
rods length
I 70°
II 72°
III 76°
IV 79°
Table 2. You can find
the protective angle (α) the table for the most com-
mon air-termination rods length. The areas bordered the horizontal plane
(roof surface) and the areas enclosed the cone
sheath can considered protected areas.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
14:42:40
14:42:40
(LLExport_02613)
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2020/01/10
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14:42:54
64
Chapter The external lightning protection system
.
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)
The structure protected (e. 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.g. (Table
2.1
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
