Chapter 3: System planning
Site planning
Page 3-10
Site grounding system
Confirm that the site has a correctly installed grounding system on a common ground ring with
access points for grounding the 450 Platform Family ODU.
If the outdoor equipment is to be installed on the roof of a high building (
Figure 38
), confirm that
the following additional requirements are met:
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 and external antenna 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
Calculated distances and power compliance margins
on
page
4-24.
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.
ODU ambient temperature limits
Select a location where the ODU can operate within safe ambient temperature limits. The
following points need to be considered while selecting a location for the ODU:
The ODU must be mounted in a Restricted Access Location (as defined in EN 60950-1) if the
operating ambient temperature may exceed 40°C, including solar radiation.
If the ambient temperature never exceeds 40°C, the temperature of the external metal case
parts of the ODU will not exceed the touch temperature limit of 70°C.
If the ambient temperature never exceeds 60°C, the temperature of the external metal case
parts of the ODU will not exceed the touch temperature limit of 90°C.
