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

STANDARDS AND GUIDELINES FOR COMMUNICATION SITES GROUNDING (EARTHING) FOR DISPATCH CENTERS AND NETWORK OPERATOR POSITIONS
All metallic equipment enclosures, frames, and chassis, as well as the operator position furniture (other
than chairs) shall be effectively bonded to the SSGB using conductors as follows:
• 16 mm 2 csa (#6 AWG) insulated copper conductor for lengths not exceeding 3.9 m (13 ft.).
• 6 mm2 csa (#10 AWG) insulated copper conductor for lengths not exceeding 3 m (10 ft.).
• If a longer length is required, the equipment grounding conductor should be sized according to
Table 5-5 on page 5-29.
Equipment mounting rails or support brackets intended for mounting equipment within the furniture
shall be bonded to the ground system by attaching a 16 mm2 csa (#6 AWG) insulated copper conductor
to a single mounting rail or bracket. In instances where an equipment chassis or housing is installed
between mounting brackets or rails and the equipment chassis or housing has a designated ground
connection point, an additional equipment grounding conductor shall be attached to the designated
grounding connection point of the equipment.
Equipotential bonding at a network operator position should be integrated into the position equipment
to the greatest extent possible. This will largely reduce the need to place equipment grounding
conductors. All telecommunication cable shields, data cable shields, and the equipment or furniture AC
equipment ground (ACEG) shall be bonded together at the position SSGB or within the equipment.
Outer shields of telecommunication cables serving the network operator position or cluster of positions
(to or from a different location) shall be bonded directly to the SSGB or by using conductors as follows:
• 16 mm 2 csa (#6 AWG) insulated copper conductor for lengths not exceeding 3.9 m (13 ft.).
• 6 mm2 csa (#10 AWG) insulated copper conductor for lengths not exceeding 1.8 m (6 ft.).
The outer shield ground is provided automatically when the cable connector contains a shield-to-chassis
connection.
When AC power is present at a network operator position, the AC power receptacle housing or ACEG
shall bond to the SSGB using a conductor as follows:
• 6 mm 2 csa (#10 AWG) insulated copper conductor for lengths not exceeding 914 mm (3 ft.)
• 16 mm2 csa (#6 AWG) insulated copper conductor for length exceeding 914 mm (3 ft.)
The conduit or raceway serving the receptacle box shall not be relied upon as the sole ACEG at the
position. A separate, insulated ACEG conductor shall be run with the branch circuit supply conductors,
and shall be properly bonded to the metallic receptacle box, conduit or armored cable per the
requirements of NFPA 70-2005. The ACEG conductors of AC branch circuits serving network operator
equipment positions shall not be electrically isolated from the building grounding and bonding network
in any way. Due to the required bonding of the ACEG conductor to the SSGB, isolated ground
receptacles shall not be used (ANSI T1.321-R2000).
Exposed metallic objects located within 2.4 m (8 ft.) vertically or 1.5 m (5 ft.) horizontally from the
operator position (such as building steel, ventilation ducts, and the nearest raised flooring system
support pedestal) shall be effectively bonded to the operator position SSGB with a minimum 16 mm 2
csa (#6 AWG) copper conductor of the shortest and straightest length possible.
68P81089E50-B 9/1/05 5-65