User's Manual

108 Link CX User Manual, Version A
A4-2 Grounding
A4-2.1 Making a Grounding Plan
A grounding plan should be developed at the outset of site design to provide the best grounding
procedures and to minimize ground loop currents. Grounding should be achieved by connecting the
outer conductors of the cables through a large-section copper strap to a central grounding point, and
the size of the conductor should be increased as each branch path is added. The final conductor should
be connected directly to the grounding system. For a radio site, a single copper grounding rod is insuf-
ficient, because its impedance is likely to be too high.
A4-2.2 Grounding Antenna Feeders
All antenna feeders should be bonded to the tower at the upper and lower ends and grounded at the
point of entry into the building. Weatherproof grounding kits are available from antenna manufacturers.
A4-2.3 Grounding Buildings
Ideally, a ground ring should surround the building and be connected to individual grounds associated
with feeder entry, antenna support structure, the building lightning conductor, the equipment room, the
main AC supply, and other facilities. Each connection should be made by the most direct route to
minimize interaction between the different grounding functions.
The ground ring should consist of copper cable or tape with electrodes two meters or longer, buried to
a depth of 0.6 m and at a distance from the building not to exceed 1 m.
Buildings may require lightning rods if they are not within the zone of another protected structure.
To construct a good ground, ground rods should penetrate the earth to a depth of about 2 m (6 feet).
Where the ground is in rocky terrain, make sure that the ground rods penetrate into loose soil. In sandy
soil, use more ground rods to make sure that the ground has sufficient contact with water-bearing
material.
Use 4 to 6 AWG wire to connect each ground rod to the equipment to be grounded. The cables should
be free of sharp bends. Each ground cable should be at least 2 m in length with at least 1 m separation
between each. Refer to local and national electrical codes to determine acceptable grounding methods.
The Link CX chassis should be directly connected to ground to ensure that it functions correctly.
In most cases, following the local code requirements for grounding and
lightning protection will be adequate.
Many of the cables used by interWAVE have braided rather than solid
outer conductors; this type of grounding is not appropriate. In these
cases surge arrestors approved by interWAVE should be used. For
information on surge arrestors, please contact the interWAVE Customer
Support department.