standards and guidelines for communication sites - Radio And ...

standards and guidelines for communication sites - Radio And ... standards and guidelines for communication sites - Radio And ...

radioandtrunking.com
from radioandtrunking.com More from this publisher
24.12.2012 Views

SPECIAL GROUNDING (EARTHING) SITUATIONS CHAPTER 4: EXTERNAL GROUNDING (EARTHING) COMMUNICATIONS SITE BUILDING TOWER FIGURE 4-65 TYPICAL LINEAR GROUNDING ELECTRODE SYSTEM GROUND RODS (8 TOTAL) 4.11.2 SITES WITH LIMITED SPACE FOR THE GROUNDING (EARTHING) ELECTRODE SYSTEM ADJACENT BUILDINGS Some sites, such as locations in metropolitan areas or areas close to adjacent buildings or property lines, have very little space available for installing a grounding (earthing) electrode system. One solution for achieving an acceptable grounding electrode system that meets the resistance requirements defined in this chapter may be to install a grounding electrode grid system using all available space on the property. A grounding electrode grid system consists of grounding electrodes, typically rods, installed in a grid pattern. The grounding electrodes are all equally spaced and connected together underground with a grounding conductor. See MIL-HDBK-419A for additional information. Requirements for a grounding electrode grid system are as follows: • The grounding electrodes shall meet the specifications and installation requirements of “Grounding (Earthing) Electrodes” on page 4-9. 4-90 68P81089E50-B 9/1/05

STANDARDS AND GUIDELINES FOR COMMUNICATION SITES SPECIAL GROUNDING (EARTHING) SITUATIONS ADJACENT BUILDINGS • Grounding conductors used to connect the grounding electrode shall meet the specifications and installation requirements of “Grounding (Earthing) Conductors” on page 4-28. Whenever possible, the grounding conductors shall be buried at least 762 mm (30 in.) deep or below the frost line, whichever is deeper. • Grounding conductors shall be bonded together wherever they intersect; this is typically completed at a ground rod or other grounding electrode. • Bonding of all components shall be made using exothermic welding or listed irreversible highcompression fittings. See “Bonding to the External Grounding (Earthing) Electrode System” on page 4-40. See Figure 4-66 for an example of a grounding electrode grid system for an available area of 9.1 m × 9.1 m (30 ft. × 30 ft.), with all ground rods separated by 3 m (10 ft.). COMMUNICATIONS GROUND RODS (16 TOTAL) SITE BUILDING TOWER FIGURE 4-66 TYPICAL GROUNDING GRID GROUNDING GRID 9.1 m (30 ft) SQUARE ROADWAY 68P81089E50-B 9/1/05 4-91

SPECIAL GROUNDING (EARTHING) SITUATIONS CHAPTER 4: EXTERNAL GROUNDING (EARTHING)<br />

COMMUNICATIONS<br />

SITE BUILDING<br />

TOWER<br />

FIGURE 4-65 TYPICAL LINEAR GROUNDING ELECTRODE SYSTEM<br />

GROUND RODS (8 TOTAL)<br />

4.11.2 SITES WITH LIMITED SPACE FOR THE GROUNDING<br />

(EARTHING) ELECTRODE SYSTEM<br />

ADJACENT<br />

BUILDINGS<br />

Some <strong>sites</strong>, such as locations in metropolitan areas or areas close to adjacent buildings or property lines,<br />

have very little space available <strong>for</strong> installing a grounding (earthing) electrode system. One solution <strong>for</strong><br />

achieving an acceptable grounding electrode system that meets the resistance requirements defined in<br />

this chapter may be to install a grounding electrode grid system using all available space on the<br />

property.<br />

A grounding electrode grid system consists of grounding electrodes, typically rods, installed in a grid<br />

pattern. The grounding electrodes are all equally spaced <strong>and</strong> connected together underground with a<br />

grounding conductor. See MIL-HDBK-419A <strong>for</strong> additional in<strong>for</strong>mation. Requirements <strong>for</strong> a grounding<br />

electrode grid system are as follows:<br />

• The grounding electrodes shall meet the specifications <strong>and</strong> installation requirements of “Grounding<br />

(Earthing) Electrodes” on page 4-9.<br />

4-90 68P81089E50-B 9/1/05

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!