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

GROUNDING (EARTHING) FOR DISPATCH CENTERS AND NETWORK OPERATOR POSITIONS CHAPTER 5: INTERNAL GROUNDING (EARTHING)
At the location where telecommunications cabling enters the building, the metallic shields shall be
bonded to the building's grounding system by one of the methods described in paragraph 5.5.1.8.4
beginning on page 5-51. Where internal backbone telecommunication cables (telephone system cables)
incorporate a shield or metallic member, the shield or metallic member shall be effectively bonded to
the closest MGB or main SSGB with a 16 mm 2 csa (#6 AWG) or coarser green jacketed grounding
conductor at the point where cables terminate or where they are broken out. Primary SPDs for interbuilding
communication cables shall be bonded to the MGB or SSGB with a 16 mm 2 csa (#6 AWG) or
coarser, green jacketed grounding conductor as described in paragraph 5.5.1.8.2 on page 5-50. When
secondary SPDs are installed at the equipment location, the SPD grounding conductor shall be
effectively bonded to the closest MGB or SSGB as described in paragraph 5.5.1.8.3 on page 5-51.
Where external antenna cables enter the building, that point of entry shall be treated as a cable entrance
location (ANSI-J-STD-607-A-2002). The cable entrance location shall have an accessible bonding
location to the building's common grounding electrode system (e.g., an external ground bus bar or
structural building steel). The outer metallic shields of each transmission line and other communications
cables shall be bonded to the building's common grounding electrode system (NFPA 70-2005, Articles
770.93, 800.100, 810.20, 820.93, 820.100, and 830.100). See “External Ground Bus Bar” on page 4-30
for additional information.
5.8 GROUNDING (EARTHING) FOR DISPATCH CENTERS AND
NETWORK OPERATOR POSITIONS
Dispatch centers co-located with communication towers require special protection considerations due to
the critical nature of their operation and due to the inherent risk to personnel from lightning events. For
optimum protection of a dispatch center, the following shall be considered:
• Site design recommendations given in “Design Considerations to Help Reduce Effects of
Lightning” on page 2-19.
• External grounding (earthing) and bonding as defined in Chapter 4, “External Grounding
(Earthing).”
• Transient voltage surge suppression (TVSS) as defined in “Telephone/Control/Data Network
Circuit SPDs” on page 7-34.
• Electrostatic discharge (ESD) precautions as defined in Appendix C.
This section provides electrical protection measures that are intended to help protect network operators,
and to help ensure reliable equipment operation during periods of lightning activity or surges from AC
power lines and power switching operations.
5-62 68P81089E50-B 9/1/05