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11 Lightning Protection
CAUTION: EMD (Lightning) damage is not covered under standard warranty. The
recommendations in this user manual, when implemented correctly, give the user the best
protection from the harmful effects of EMD. However 100% protection is neither implied nor
possible.
11.1 Overview
The idea of lightning protection is to protect structures, equipment and people against
lightning by conducting the lightning current to ground via a separate preferential solid path.
The following should be treated as a guide only, the actual degree of lightning protection
required depends on local conditions and weather patterns and applicable local regulations.
Full details of lightning protection methods and requirements can be found in the international
standards IEC 61024-1 and IEC 61312-1, the U.S. National Electric Code ANSI/NFPA No.
70-1984 or section 54 of the Canadian Electric Code.
11.1.1 Lightning Protection Zones
The installation of the ODU can be classified into two different lightning protection zones:
•
Zone A: In this zone a direct lighting strike is possible.
•
Zone B: In this zone a direct lightning strike is unusual, but the full electromagnetic field is
still present.
The zones are determined using the 'rolling sphere method', an imaginary sphere, typically 50
meter in radius is rolled over the structure. All structure points that contact the sphere, (Zone
A) indicate the zone where a direct strike is possible. Similarly points that do not contact the
sphere indicate a zone (zone B) where a direct strike is less likely.
The following diagrams (Figure 92 & Figure 93) show this zoning pictorially:
Equipment mounted in Zone A should be capable of carrying the full lightning current.
Mounting of the ODU in Zone A is not recommended. Mounting in Zone A should only be
carried out observing the rules governing installations in Zone A
structures, equipment and life at risk.
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Local regulations may also require the fitting of the 8 AWG ground wire referred below.
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11 Lightning Protection
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Failure to do so may put
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