standards and guidelines for communication sites - Radio And ...
standards and guidelines for communication sites - Radio And ... standards and guidelines for communication sites - Radio And ...
BONDING EQUIPMENT TO INTERNAL GROUNDING (EARTHING) SYSTEM CHAPTER 5: INTERNAL GROUNDING (EARTHING) 5.5.1.1 SEPARATELY DERIVED AC SYSTEMS Separately derived AC electrical power systems have no direct electrical connection between the incoming neutral from the AC power source and the neutral conductor on the secondary side of the separately derived AC power system. Separately derived power systems can include isolation transformers, step-down or step-up transformers, generator AC power systems that are breaking the neutral conductor inside the auto transfer switch (ATS), Uninterruptible Power Supply (UPS) systems that are configured as separately derived systems, or AC inverters that are powered by a battery bank. If a separately derived AC power system exists at the site within the communication system equipment area, a grounding conductor for the neutral to ground bond on the secondary side of the unit shall be bonded back to the equipment area's single point grounding system (MGB or SSGB, where the MGB is not co-located) with a 35 mm 2 csa (#2 AWG) or coarser, green-jacketed grounding conductor. Where applicable, the grounding conductor should be up-sized to meet NFPA 70-2005, Article 250.66 requirements. The grounding conductor shall be bonded to both locations with compression-type, twohole, UL 486A listed lugs as described within this chapter. If a separately derived AC power system exists at the site but not located at the communication system equipment area, a grounding conductor for the neutral to ground bond on the secondary side of the unit shall be referenced back to the common building grounding electrode system with no less than a 35 mm 2 csa (#2 AWG) or coarser, copper grounding conductor. NOTE: Generators are often shipped from the manufacturer with a neutral to ground bond established within the generator unit. If the generator's ATS panel is not configured as a separately derived system, this bonding conductor must be removed. N N GE N EG MAIN BONDING JUMPER G SERVICE ENTRANCE EQUIPMENT TRANSFER SWITCH FIGURE 5-26 GENERATOR SYSTEM WITH SWITCHED NEUTRAL SEPARATELY DERIVED SYSTEM 5-42 68P81089E50-B 9/1/05 N N G N EG N LOAD G BONDING JUMPER N GEN N GE G EG TO NEAR BY ELECTRODE REFERENCED TO BUILDING MAIN AC GROUND
STANDARDS AND GUIDELINES FOR COMMUNICATION SITES BONDING EQUIPMENT TO INTERNAL GROUNDING (EARTHING) SYSTEM SEPARATELY DERIVED TRANSFORMER EG TO MAIN NEUTRAL- TO-GROUND BOND GE FIGURE 5-27 GROUNDING OF A DRY TYPE ISOLATION TRANSFORMER 5.5.1.2 DC POWER PLANT GE G N The main DC power plant return bus shall be bonded to the facility single point grounding (earthing) system through a connection to the equipment room's single point ground. This single point ground should be the MGB, unless the MGB is located elsewhere in the building. In this case the grounding conductor can be effectively bonded to a properly installed SSGB. The DC power plant return bus shall be bonded to the single point ground with a grounding conductor no smaller than the largest conductor supplied by the DC power system, or no smaller than the grounding conductor for the SSGB and the grounding electrode conductor for the MGB. The DC power plant ground conductor shall be bonded to both bus bars with a compression-type two-hole UL 486A listed lug as described within this chapter. See Figure 5-28 for an example of this type of bonding configuration along with the required bonding of the power plant rack and battery rack frames (NFPA 70-2005, Articles 250.162, 250.164, and 250.166). 68P81089E50-B 9/1/05 5-43 EG POWER DISTRIBUTION PANELBOARD WITH MAIN OVERCURRENT PROTECTION DEVICE N G NEUTRAL-TO-GROUND BOND EITHER AT TRANSFORMER OR PANEL (ONE LOCATION ONLY) TO LOAD N EG
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STANDARDS AND GUIDELINES FOR COMMUNICATION SITES BONDING EQUIPMENT TO INTERNAL GROUNDING (EARTHING) SYSTEM<br />
SEPARATELY DERIVED<br />
TRANSFORMER<br />
EG<br />
TO MAIN NEUTRAL-<br />
TO-GROUND BOND<br />
GE<br />
FIGURE 5-27 GROUNDING OF A DRY TYPE ISOLATION TRANSFORMER<br />
5.5.1.2 DC POWER PLANT<br />
GE<br />
G<br />
N<br />
The main DC power plant return bus shall be bonded to the facility single point grounding (earthing)<br />
system through a connection to the equipment room's single point ground. This single point ground<br />
should be the MGB, unless the MGB is located elsewhere in the building. In this case the grounding<br />
conductor can be effectively bonded to a properly installed SSGB. The DC power plant return bus shall<br />
be bonded to the single point ground with a grounding conductor no smaller than the largest conductor<br />
supplied by the DC power system, or no smaller than the grounding conductor <strong>for</strong> the SSGB <strong>and</strong> the<br />
grounding electrode conductor <strong>for</strong> the MGB. The DC power plant ground conductor shall be bonded to<br />
both bus bars with a compression-type two-hole UL 486A listed lug as described within this chapter.<br />
See Figure 5-28 <strong>for</strong> an example of this type of bonding configuration along with the required bonding of<br />
the power plant rack <strong>and</strong> battery rack frames (NFPA 70-2005, Articles 250.162, 250.164, <strong>and</strong> 250.166).<br />
68P81089E50-B 9/1/05 5-43<br />
EG<br />
POWER DISTRIBUTION<br />
PANELBOARD WITH<br />
MAIN OVERCURRENT<br />
PROTECTION DEVICE<br />
N<br />
G<br />
NEUTRAL-TO-GROUND BOND<br />
EITHER AT TRANSFORMER OR PANEL<br />
(ONE LOCATION ONLY)<br />
TO LOAD<br />
N<br />
EG
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