AT&T Release 2.0 Manuel D’Utilisation
Installing the Control Unit
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concrete-encased ground—must be an electrode, consisting of one of
the following:
—
at least 20 ft (6.1 m) of one or more steel reinforcing rods, each
being at least ½-inch (1.27 cm) in diameter
being at least ½-inch (1.27 cm) in diameter
— 20 ft (6.1 m) of bare copper conductor not smaller than
#4 AWG, encased in 2 inches (5 cm) of concrete.
— This electrode must be located within and near the bottom of a
concrete foundation or footing that is in direct contact with the
earth.
earth.
— ground ring-consists of at least 20 ft (6.1 m) of bare copper
conductor not smaller than #2 AWG encircling the building.
The ground ring must be in direct contact with the earth and
buried at least 2.5 ft (77 cm) below the earth’s surface.
The ground ring must be in direct contact with the earth and
buried at least 2.5 ft (77 cm) below the earth’s surface.
WARNING:
Do not use metal underground gas piping system—this is a
safety risk.
safety risk.
Central Office Trunk Protection
The telephone company is responsible for providing the following protection
of central office trunks at the entrance to the site:
of central office trunks at the entrance to the site:
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carbon blocks or gas discharge tubes connected to an approved
ground
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adequate bonding of the central office trunk protector ground and the
power company ground
2-14
Power and Grounding