5 0.5
• OBO GFK insulating rods: km
= 0.06
• Protection classes III and IV: ki
= 0.7
If several insulating materials are used, practice the lowest value for km
is used.44
The values apply all type earthers and those type earthers which the
earther resistance the neighbouring earther electrodes does not differ more than
a factor the earther resistance individual electrodes deviates more than
a factor kc
= should assumed.7: Calculating the separation distance according IEC 62305-3
Example: building structure
Initial situation:
• Lightning protection class III
• Building with more than four down-conductors
• Material: concrete, brickwork
• Height/point which the separation distance
should calculated: m
Value determined:
• 0.TBS
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Procedure for calculating the separation distance according DIN 62305-3
1st step
Calculate the value the coeffi-
cient ki
• Protection class ki
= 0.
3rd step
Calculate the value the coeffi-
cient km
• Material air: km
= 1
• Material concrete, brickwork: km
= 0.66
• conductors and more: kc
= 0.44
• 0.5
• m
Calculation separation distance:
s kc/km 0.04 0.04
• 0.
TBS
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75
Chapter The external lightning protection system
.35 m
More detailed calculation methods
for complex buildings and systems
are described IEC/EN 62305-3.08
• Protection class II: ki
= 0.
Table 2.
4th step
Calculate the value L
L the vertical distance from the point which the separation distance (s) calcu-
lated the closest point the equipotential bonding.04
2nd step
Calculate the value the coeffi-
cient kc
(simplified system)
• conductor (only the case isolated lightning protection system): kc
= 1
• conductors: kc
= 0.44/0
