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J Install and cable a CMC1 cabinet
Check AC power and ground for CMC1
358 S8100 Installation and Upgrades
November 2003
Approved grounds
An approved ground is the closest acceptable medium for grounding the building entrance protector,
entrance cable shield, or single-point ground of electronic telephony equipment. If more than one type of
approved ground is available on the premises, the grounds must be bonded together as required in
Section 250-81 of the National Electrical Code.
Grounded Building Steel – The metal frame of the building where it is effectively grounded by 1 of the
following grounds: acceptable metallic water pipe, concrete-encased ground, or a ground ring.
Acceptable Water Pipe – A metal underground water pipe, at least ½ inch (1.3 cm) in diameter, in direct
contact with the earth for at least 10 feet (3 m). The pipe must be electrically continuous (or made
electrically continuous by bonding around insulated joints, plastic pipe, or plastic water meters) to the
point where the protector ground wire connects. A metallic underground water pipe must be
supplemented by the metal frame of the building, a concrete-encased ground, or a ground ring. If these
grounds are not available, the water pipe ground can be supplemented by 1 of the following types of
grounds:
• Other local metal underground systems or structures – Local underground structures such as tanks
and piping systems
• Rod and pipe electrodes – A 5/8-inch (1.6-cm) solid rod or 3/4-inch (2-cm) conduit or pipe
electrode driven to a minimum depth of 8 feet (2.4 m)
• Plate electrodes – Must have a minimum of 2 ft
2
(0.185 m
2
) of metallic surface exposed to the
exterior soil
Concrete Encased Ground – An electrode encased by at least 2 inches (5.1 cm) of concrete and located
within and near the bottom of a concrete foundation or footing in direct contact with the earth. The
electrode must be at least 20 feet (6.1 m) of 1 or more steel reinforcing bars or rods ½ inch (1.3 cm) in
diameter, or at least 20 feet (6.1 m) of bare, solid copper, 4 AWG (26 mm
2
) wire.
Ground Ring – A buried ground that encircles a building or structure at a depth of at least 2.5 feet (0.76
m) below the earth’s surface. The ground ring must be at least 20 feet (6.1 m) of 2 AWG (35 mm
2
), bare,
copper wire.
Approved floor grounds
!
WARNING:
If the approved ground is inside a dedicated equipment room, then these connections must be made
by a qualified electrician.
Floor grounds are those grounds on each floor of a high-rise building that are suitably connected to the
riser closet’s ground terminal and to the cabinet’s single-point ground terminal. Approved floor grounds
may include:
• Building steel
• The grounding conductor for the secondary side of the power transformer feeding the floor
• Metallic water pipes
• Power-feed metallic conduit supplying panel boards on the floor
• A grounding point specifically provided in the building for the purpose