5
• m
Calculation separation distance:
s kc/km 0.04
• 0.7: 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:
• 0.04 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
= 0.06
• Protection classes III and IV: ki
= 0.5
• OBO GFK insulating rods: km
= 0.5 0.08
• Protection class II: ki
= 0.35 m
More detailed calculation methods
for complex buildings and systems
are described IEC/EN 62305-3.44/0.04
2nd step
Calculate the value the coeffi-
cient kc
(simplified system)
• conductor (only the case isolated lightning protection system): kc
= 1
• conductors: kc
= 0.
Table 2.
3rd step
Calculate the value the coeffi-
cient km
• Material air: km
= 1
• Material concrete, brickwork: km
= 0.44
• 0.7
If several insulating materials are used, practice the lowest value for km
is used.66
• conductors and more: kc
= 0.44
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.
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.
TBS
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75
Chapter The external lightning protection system
