Lightning Protection; Overview; Lightning Protection Zones - Motorola PTP 300 series User Manual

Lightning Protection

11 Lightning Protection
EMD (Lightning) damage is not covered under standard 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 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 and 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
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the rules governing installations in Zone A Failure to do so may put structures, equipment and
life at risk.
Equipment mounted in Zone B should be grounded using grounding wire of at least 10 AWG. This
grounding wire should be connected to a grounding rod or the building grounding system before
entry in to building.
The PTP 300 Series bridge ODU grounding point can be found on the bottom of the unit. The
300 Series Bridge is supplied with an appropriate grounding lug for attachment to the ODU.
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Local regulations may also require the fitting of the 8 AWG ground wire referred below.
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