Instruction manual

AC Power and Grounding
2-15
Installing the Control Unit
— 20 feet (6.1 m) of bare copper conductor not smaller than #4 AWG,
encased in 2 inches (5 cm) of concrete
— Ground ring, consisting of at least 20 feet (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 1/2 feet (77 cm) below the earth’s surface.
WARNING:
Do not use a metal underground gas piping system—this is a
safety risk.
Central Office Trunk Protection 2
The local telephone company is responsible for providing the following
protection of central office trunks at the entrance to the site:
■ Carbon blocks or gas discharge tubes connected to an approved ground.
■ Adequate bonding of the central office trunk protector ground and the
power company ground.
CAUTION:
Check these requirements with a simple, visual inspection. If you
cannot verify that the central office grounding requirements are met,
contact the central office. Do not connect the control unit to the
central office trunks until you are certain that these requirements are
met.
This electrode must be located within and near the bottom of a
concrete foundation or footing that is in direct contact with the
earth.