68P80801E30-A 5/1/2002 3-15
Gen 3 Site Controller System Manual Chapter 3 Pre-Installation
Grounding Requirements
Grounding Requirements
The site must meet certain specifications for adequate protection from
lightning induced transients. Proper ground installation methods are outlined
in the Motorola Standards and Guidelines for Communication Sites
68P81089E50 manual (formerly ‘R56’).
Note: Should inconsistencies exist, grounding requirements specified in the
Motorola Standards and Guidelines for Communication Sites
68P81089E50 manual shall supercede the requirements in this
manual.
Ground Rings
Two separate ground rings should surround the site building and antenna
tower. Ground rods (8’) should be driven into the ground at 10’ intervals for
average soil. The two ground rings should be bonded together with one wire,
buried at least 18” underground, or below frost level.
These ground rings are referred to as the exterior primary ground and must
be at least #2 AWG tinned copper wire, solid or stranded. All connections to
the rings should be made by exothermic welding. All exothermic welded
connections should be treated with cold galvanizing spray.
Inspection wells should be provided for access to the buried ground system
to allow verification of ground resistance. The ground resistance should be
less than 5Ω .
Tower Grounding
Ground each leg of the antenna tower with an 8’ ground rod driven near each
leg. All ground connections to the antenna tower must be exothermically
welded. Do not weld directly on tower structural members; weld only to
provided tower grounding tabs or to tower feet.
Note: Make sure that welding ground connections to the antenna tower
does not void the warranty of the tower.
Metal monopole towers require a minimum of three 8’ long ground rods to
be driven into the ground, spaced approximately 10’ apart. These ground
rods may be exothermically welded to the bottom portion of the mast itself,
to the monopole footing, or to the grounding connection tabs provided.
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