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Chapter 3: System planning
Drop cable grounding points
To estimate how many grounding kits are required for each drop cable, refer to the site installation
diagrams
(Figure 23 , Figure 24
•
The drop cable shield must be grounded near the ODU at the first point of contact between the
drop cable and the mast, tower or building.
•
The drop cable shield must be grounded at the building entry point.
For mast or tower installations
•
The drop cable shield must be grounded at the bottom of the tower, near the vertical to
horizontal transition point. This ground cable must be bonded to the tower or tower ground
bus bar (TGB), if installed.
•
If the tower is greater than 61 m (200 ft
the tower midpoint, and at additional points as necessary to reduce the distance between
ground cables to 61 m (200 ft) or less.
•
In high lightning-prone geographical areas, the drop cable shield must be grounded at spacing
between 15 to 22 m (50 to 75 ft
For roof installations
(Figure
•
The drop cable shield must be bonded to the building grounding system at its top entry point
(usually on the roof).
•
The drop cable shield must be bonded to the building grounding system at the entry point to
the equipment room.
LPU location
Find a location for the top LPU that meets the following requirements:
•
There is room to mount the LPU, either on the ODU mounting bracket or on the mounting pole
below the ODU.
•
The drop cable length between the ODU and top LPU must not exceed 600 mm.
•
There is access to a metal grounding point to allow the ODU and top LPU to be bonded in the
following ways: top LPU to ODU; ODU to grounding system.
Find a location for the bottom LPU that meets the following requirements:
•
The bottom LPU can be connected to the drop cable from the ODU.
•
The bottom LPU is within 600 mm (24 in) of the point at which the drop cable enters the
building, enclosure or equipment room within a larger building.
•
The bottom LPU can be bonded to the grounding system.
and
Figure
25) and use the following criteria:
(Figure
23), use the following additional criteria:
in height, the drop cable shield must be grounded at
)
. This is especially important on towers taller than 45 m (150 ft).
)
25), use the following additional criteria:
Page
3-13
Site planning
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