Motorola PTP 400 Series - Manual (Page 144)

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11 Lightning Protection
EMD
(
Lightning
) damage is not covered under warranty
The recommendations in this user manual when installed correctly give
the user the best protection from the harmful effects of EMD
However 100% protection is not implied or 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
and by reducing the electromagnetic field.
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 un-attenuated
electromagnetic field is still present.
The zones are determined using the ‘rolling sphere method’, an imaginary sphere, typically 50
meters (164 feet) 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 76 and Figure 77) show this zoning pictorially: