Motorola PTP 500 User's Guide download pdf (Page 102)

Grounding and lightning protection Chapter 2 Planning considerations

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Sep 2010

Grounding and lightning protection

Structures, equipment and people must be protected against power surges (typically

caused by lightning) by conducting the surge current to ground via a separate

preferential solid path.

The actual degree of protection required depends on local conditions and applicable

local regulations.

Motorola recommends that PTP 300 and PTP 500 installation is contracted to a

professional installer.

WARNING

Electro-magnetic discharge (lightning) damage is not covered under

warranty. The recommendations in this guide, when followed

correctly, give the user the best protection from the harmful effects

of EMD. However 100% protection is neither implied nor possible.

Standards

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.

Lightning protection zones

The ‘rolling sphere method’ is used to determine where it is safe to mount equipment.

An imaginary sphere, typically 50 meters in radius, is rolled over the structure. Where

the sphere rests against the ground and a strike termination device (such as a finial or

ground bar), all the space under the sphere is considered to be in the zone of

protection (Zone B). Similarly, where the sphere rests on two finials, the space under

the sphere is considered to be in the zone of protection.

Assess locations on masts, towers and buildings to determine if the location is in Zone

A or Zone B:

• Zone A: In this zone a direct lightning strike is possible. Do not mount equipment

in this zone.

• Zone B: In this zone, direct EMD (lightning) effects are still possible, but

mounting in this zone significantly reduces the possibility of a direct strike.

Mount equipment in this zone.

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Motorola PTP 500 User's Guide Page 102