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STANDARDS AND GUIDELINES FOR COMMUNICATION SITES SPECIAL GROUNDING (EARTHING) SITUATIONS<br />

4.11.1 ROOFTOP AND INTEGRATED COMMUNICATIONS SITES<br />

Rooftop <strong>and</strong> integrated <strong>communication</strong>s <strong>sites</strong> (high-rise buildings) may require special techniques <strong>for</strong><br />

achieving a suitable grounding (earthing) electrode system when effectively grounded structural steel is<br />

not available <strong>and</strong> when encircling the building with a ground ring would not be feasible, such as in a<br />

downtown metropolitan location. Some options may be:<br />

• Consult with Motorola Engineering or other engineering firm.<br />

• Installation of a small ground ring in an available location. See Figure 4-64.<br />

• Installation of multiple parallel rods in a straight line. See Figure 4-65.<br />

• Installation of electrolytic ground rod systems.<br />

IMPORTANT: If a supplemental grounding electrode system is installed, it shall be bonded to the<br />

existing building grounding electrode system. See “Common Grounding (Earthing)” on page 4-5<br />

NOTE: In order to maintain maximum efficiency of parallel ground rods, the ground rods shall be separated<br />

from one another by twice the length of the individual ground rods.<br />

EXTERIOR WWALL<br />

EXOTHERMICALLY LY WELDED<br />

OR HIGH-COMPRESSION<br />

CONDUCTOR BOND<br />

GROUND ROD BOND<br />

RECOMMENDED MINIMUM<br />

GROUND ROD SEPARA P ATION<br />

IS 4.9 m (16 ft.)<br />

CONDUCTOR<br />

PVC CONDUIT T GUARD<br />

32 mm (1.25 in.) x 2.1 m (7 ft.)<br />

CABLE FASTENERS<br />

F<br />

INSTALLED T EVER Y 914 mm (3 ft.)<br />

PVC EXTENDED<br />

305 mm (1 ft.)<br />

BELOW FINISHED GRADE<br />

GROUND RING<br />

FIGURE 4-64 SMALL GROUND RING INSTALLATION<br />

BOND BETWEEN SMALL<br />

GROUND RING AND<br />

EXISTING GROUNDING<br />

ELECTRODE SYSTEM<br />

68P81089E50-B 9/1/05 4-89

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