Cambium Networks cnWave, User Manual

Page: 71 / 248

System Planning 71
Warning
Never mount equipment in Zone A. Mounting in Zone A may put equipment, structures and
life at risk.
Site grounding system
Ensure 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 the Installation section.
Ensure that the system meets the following additional requirements:
l
A grounding conductor is installed around the roof perimeter to form the main roof perimeter
lightning protection ring.
l
Air terminals are installed along the length of the main roof perimeter lightning protection ring,
typically every 6.1 m (20 ft).
l
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:
l
The equipment is high enough to achieve the best radio path.
l
People can be kept a safe distance away from the equipment when it is radiating.
l
The equipment is lower than the top of the supporting structure (tower, mast, or building) or its
lightning air terminal.
l
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 weather proofing 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 mid-point 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:
l
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.
l
The drop cable shield must be grounded at the building entry point.
For mast or tower installations installation, use the following additional criteria:
l
The drop cable shield must be grounded at the bottom of the tower, near the vertical to the
horizontal transition point. This ground cable must be bonded to the tower or tower ground bus