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

STANDARDS AND GUIDELINES FOR COMMUNICATION SITES
Chapter 4. External Grounding (Earthing) .................................................... 4-1
4.1 Introduction .................................................................................................................................4-1
4.2 Lightning Activity and Exposure ..................................................................................................4-3
4.3 Common Grounding (Earthing) ...................................................................................................4-5
4.4 Grounding (Earthing) Electrode System Component and Installation Requirements .................4-7
4.4.1 Grounding (Earthing) Electrodes ........................................................................................4-9
4.4.2 Grounding (Earthing) Conductors .....................................................................................4-28
4.4.3 External Ground Bus Bar ..................................................................................................4-30
4.5 Dissimilar Metals and Corrosion Control ...................................................................................4-34
4.5.1 Corrosion Related to Soil Type .........................................................................................4-34
4.5.2 Galvanic Corrosion ...........................................................................................................4-36
4.5.3 Miscellaneous General Information ..................................................................................4-38
4.5.4 Methods To Help Reduce Corrosion ................................................................................4-38
4.6 Bonding to the External Grounding (Earthing) Electrode System .............................................4-40
4.6.1 Requirements ...................................................................................................................4-40
4.6.2 Bonding Methods ..............................................................................................................4-41
4.7 Minimum Site Grounding (Earthing) Requirements ..................................................................4-44
4.7.1 Type “A” Site - Light Duty .................................................................................................4-44
4.7.2 Type “B” Site - Standard Duty ..........................................................................................4-45
4.7.3 Special Grounding (Earthing) Situations ..........................................................................4-45
4.7.4 Grounding (Earthing) Electrode System Resistance Requirements .................................4-46
4.7.5 Type “A” Site Grounding (Earthing) ..................................................................................4-48
4.7.6 Tower Grounding (Earthing) .............................................................................................4-50
4.7.7 Dedicated Communications Building Grounding (Earthing) .............................................4-59
4.7.8 Outdoor Cabinet Grounding (Earthing) .............................................................................4-61
4.7.9 RF Transmission Line and Preamplifier Grounding (Earthing) .........................................4-62
4.7.10 Metallic Objects Requiring Bonding ................................................................................4-67
4.7.11 Metallic Building Siding Grounding (Earthing) ................................................................4-74
4.8 Grounding (Earthing) Roof-Mounted Antenna Masts and Metal Support Structures ................4-74
4.8.1 Side Mounted Antenna Grounding (Earthing) ..................................................................4-77
4.9 Grounding (Earthing) Rooftop Mounted Tower Structures .......................................................4-79
4.10 Special Grounding (Earthing) Applications .............................................................................4-81
4.10.1 External Grounding (Earthing) For Dispatch Centers Co-located
With Communications Towers ................................................................................................4-81
4.10.2 Two or More Electrically Interconnected Separate Buildings Located
in the Same General Area .......................................................................................................4-83
4.10.3 Access Point and Wireless Router Grounding (Earthing) ...............................................4-84
4.10.4 Metal Shipping Containers Used As Communications Buildings ...................................4-87
4.10.5 Grounding (Earthing) Electrode Systems Covered by Concrete or Asphalt ...................4-88
4.11 Special Grounding (Earthing) Situations .................................................................................4-88
4.11.1 Rooftop and Integrated Communications Sites ..............................................................4-89
4.11.2 Sites With Limited Space for the Grounding (Earthing) Electrode System .....................4-90
4.11.3 Towers With Limited Space For A Ground Ring .............................................................4-92
4.11.4 Stone Mountain Tops .....................................................................................................4-92
4.11.5 Sand, Coral, or Limestone Environments .......................................................................4-96
4.11.6 Shallow Topsoil Environments .......................................................................................4-97
4.11.7 Grounding (Earthing) in Arctic Regions ..........................................................................4-99
68P81089E50-B 9/1/05 III