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GROUNDING (EARTHING) SYSTEM COMPONENTS AND INSTALLATION REQUIREMENTS CHAPTER 5: INTERNAL GROUNDING (EARTHING)
5.3.5 GROUND (EARTH) BUS CONDUCTORS
GROUND BUS
CONDUCTORS -
ALL CONDUCTORS
ROUTED TO MGB
INDIVIDUAL EQUIPMENT
GROUNDING
CONDUCTORS FROM
EACH PIECE OF
EQUIPMENT AND RACK
TO THE GROUND BUS
CONDUCTOR
RGB MOUNTED ON
RACK CABLE
MANAGEMENT
SYSTEM
GROUND BUS
CONDUCTOR EXTENDED
TO BOTTOM OF RACK
TO ACCOMMODATE
FUTURE GROWTH
Ground (earth) bus conductors interconnect the MGB, SSGB, RGB and the equipment grounding
conductor with the cabinets, racks or individual system or subsystem components. The end of the
conductor opposite the MGB or SSGB typically remains unterminated, although this end of the
conductor may be terminated to a cabinet, rack, individual system component or RGB.
Ground bus conductors typically originate at the MGB and radiate throughout the equipment area
generally within the cable tray system. These conductors may extend into an adjoining subsystem
equipment area and may serve as the grounding conductor for a SSGB, or RGB. Ground bus conductors
shall be bonded to the MGB, SSGB, or RGB using methods described within this chapter.
Ground bus conductors may have ground bus extension conductors to provide a ground bus within cross
section segments of a cable tray system. These ground bus extension conductors shall be of the same
specification as the ground bus conductor and shall be routed with all connections to the ground bus
conductor pointed in the direction of the MGB or SSGB. The ground bus extension conductor shall be
bonded to the ground bus conductor using suitable methods described within this chapter.
Equipment grounding conductors from each cabinet, rack or individual system component chassis shall
be bonded to the ground bus conductor or ground bus extension conductor using methods described
within this chapter. See Figure 5-17. Ground bus conductors are not required to be installed at all
locations, provided that equipment grounding conductors from each cabinet, rack and individual system
component extend to the MGB or SSGB.
TOP-MOUNTED RGB
EQUIPMENT
GROUNDING
CONDUCTORS
EQUIPMENT
GROUNDING
TERMINAL
(TYPICAL EACH
PIECE OF
EQUIPMENT)
VERTICALLY
MOUNTED RGB
MINIMUM BENDING
RADIUS MUST BE
MAINTAINED ON ALL
CONDUCTORS
FIGURE 5-17 ACCEPTABLE METHODS FOR BONDING FROM THE EQUIPMENT TO THE MGB
5-24 68P81089E50-B 9/1/05