User's Guide

Chapter 4: System planning
43
Site grounding system
Confirm that the site has a correctly installed grounding system on a common ground ring with access points for grounding
ODU.
If the outdoor equipment is to be installed on the roof of a high building, refer to Installation section. Ensure that the system
meets the following additional requirements:
•
A grounding conductor is installed around the roof perimeter to form the main roof perimeter lightning protection
ring.
•
Air terminals are installed along the length of the main roof perimeter lightning protection ring, typically every
6.1m (20ft).
• The main roof perimeter lightning protection ring contains at least two down conductors connected to the
grounding electrode system. The down conductors should be physically separated from one another, as far as
practical.
ODU location
Find a location for the ODU (and external antenna for connectorized units) that meets the following requirements:
• The equipment is high enough to achieve the best radio path.
• People can be kept a safe distance away from the equipment when it is radiating. The safe separation distances
are defined in Legal and regulatory information.
• The equipment is lower than the top of the supporting structure (tower, mast or building) or its lightning air
terminal.
• If the ODU is connectorized, select a mounting position that gives it maximum protection from the elements, but
still allows easy access for connecting and weatherproofing the cables. To minimize
cable losses, select a position
where the antenna cable lengths can be minimized. If diverse or two
external antennas are being deployed, it is not
necessary to mount the ODU at the midpoint of the antennas.
Drop cable grounding points
To estimate how many grounding kits are required for each drop cable, refer to site installation and use the following criteria:
• The drop cable shield must be grounded near the ODU at the first point of contact between the drop cable and the mast
installation, tower or building.
• The drop cable shield must be grounded at the building entry point.
For mast or tower installations installation, use the following additional criteria:
• 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) in height, the drop cable shield must be grounded at the tower midpoint,
and at additional points as necessary to reduce the distance between ground cables to 61 m (200 ft) or less.
Warning
Never mount equipment in Zone A. Mounting in Zone A may put equipment, structures and life at risk.