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

STANDARDS AND GUIDELINES FOR COMMUNICATION SITES BONDING EQUIPMENT TO INTERNAL GROUNDING (EARTHING) SYSTEM
• Metallic raised flooring systems
• HVAC grills, ducts, units, motors, motor controllers, control panels, junction and terminal boxes
• Panelboards
• Switchboards
• Automatic and manual transfer switches
• Transformers
• UPS units
• Metallic housing of AC power surge suppressor devices
• Primary surge suppressor ground terminals
The following shall also be bonded to the MGB, SSGB or IPGB system:
• All metallic support apparatus, including metallic conduits, within an equipment shelter, room, a
generator or power distribution room, or specific equipment area and located within 2.4 m (8 ft.)
vertically or 1.5 m (5 ft.) horizontally of ground or grounded metal objects (NFPA 70-2005, Article
250 (VI)).
• Rigid Metallic Conduit (RMC) and Electrical Metallic Tubing (EMT). EXCEPTION: when the
conduits are effectively joined with threaded coupling, threadless coupling, or threadless
compression connector, that terminate in bonded metallic enclosures, they may be considered
adequately bonded and do not require additional bonding (ANSI T1.334-2002).
• If metallic conduit does not meet the above specifications, the electrical metallic conduits shall be
bonded to the IPGB conductor at any point where they cross within 152 mm (6 in.) of the IPGB
conductor.
• Metallic conduit run parallel to the IPGB conductor shall be bonded at the points where it enters to
within 152 mm (6 in.) of the IPGB conductor and at the point where it transitions away from the
IPGB conductor.
• All set-screw type connectors and couplings shall be bridged with a bonding jumper.
• Each metallic conduit may be connected to the IPGB conductor with a continuous equipment
grounding conductor using removable saddle clamps or other clamps that specifically permit the
use of a single continuous conductor for grounding multiple runs of conduit. If multiple conduits
are grounded using a single conductor, the conductor shall be clamped to each conduit run such
that removal of one clamp does not interrupt the path to ground for the other conduit runs. See
Figure 5-30 on page 5-48.
68P81089E50-B 9/1/05 5-47