Rooftop (Elevated); New Concrete Pad - Motorola SC 4812ET RF Hardware Installation Manual

Site Preparation
2

Rooftop (Elevated)

New Concrete Pad

50
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Refer to Figure 2-5 and Figure 2-6 for proper position of mounting
locations when designing the support structure.
For most rooftop installations all of the connections to the cabinet will
be made through the rear of the cabinet I/O area. For this reason, the
cabinet must be set in place and bolted down prior to running any
conduits or wiring. Conduit/wire routing will be discussed in Chapter 5.
Lightning protection is included in the cabinet. A good earth ground
(ground system resistance must be less than 10 Ohms, with 5 Ohms or
less being the goal) is required for the lightning protection equipment to
perform properly. Refer to Motorola's guidelines (Motorola Publication
68P81150E62) for details on the design of a grounding system. Conform
to local electrical construction standards for conduit materials and sizing.
For a rooftop installation which is elevated sufficiently above the roof
surface, most of the connections can be made through the bottom of the
cabinet by terminating the conduit at the bottom of the rear I/O area. See
Figure 2-6 for recommended conduit/cable entrance layout.
Variations in pad construction methods may be required to comply with
local conditions, practices, or building codes.
Install the grounding system, and electrical conduits (see Figure 2-3,
Figure 2-4, and Figure 2-6) prior to pad construction. Refer to the
Motorola guidelines (Motorola Publication 68P81150E62) for details on
the design of a grounding system. Conform to local electrical
construction standards for conduit materials and sizing. Refer to
Table 2-6 and Table 2-7 for minimum bend radius of antenna cables and
maximum number of cables in a conduit.
If it is desired to make cabling through the bottom of the cabinets, it is
recommended that the conduits be positioned using the dimensions
given in Figure 2-5 prior to pouring the concrete pad. Installation in this
manner allows for the connections to the RF and Power Cabinet to be
made through the bottom of the I/O area, although it may be desirable to
make the antenna connections through the rear wall. For the connections
that are made through the bottom of the I/O area, conduits and wiring
can be installed prior to arrival of the cabinet.
SC 4812ET RF and Power Cabinet Hardware Installation Manual
TM
CAUTION
The mounting surface must be flat. Door closure problems
may occur if the cabinets are not installed on a flat surface.
To help reduce the chance of damage caused by lightning
strikes, it is required that a ground ring be constructed
when the pad is built. See section titled "Ground System
Installation".
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Apr 2001
DRAFT