Chapter 3: System planning Site planning
Page 3-9
• Availability of a mains electricity supply.
• Located in an environment where it is not likely to exceed its operational temperature rating, allowing for
natural convection cooling.
• Accessibility for viewing status indicator LED and connecting Ethernet cables.
• Cable lengths; see ODU interfaces on page 2-26.
Maximum cable lengths
When installing PMP/PTP 450i Series ODU, the maximum permitted length of the shielded copper Ethernet
interface cable is 330 feet (100m) from AP/BHM/SM/BHS to their associated power supplies or CMM4.
Grounding and lightning protection
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.
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. To adequately protect a PMP/PTP 450
platform installation, both ground bonding and transient voltage surge suppression are required.
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
Use the rolling sphere method (Figure 32) 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.
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