AT&T 3.0 Telephone User Manual


 
AC Power and Grounding
Grounding Requirements
Proper grounding of the installation site safeguards the system by protecting it
from the following:
Lightning
Power surges
Power crosses on central office trunks
Electrostatic discharge (ESD)
When installing the control unit, make sure you meet the following grounding
requirements:
The control unit, the central office trunk protector, and the AC power
service panel should be as close to each other as possible.
Because equipment can be located throughout a building, the
National Electrical Code requires that the ground point for the central
office trunk protector be bonded to the AC power ground as shown in
Figure 2-3.
The AC outlet and the single-point ground bar must be properly
grounded as shown in Figure 2-1 and Figure 2-3.
Each power supply in the control unit must be connected to the single-
point ground bar by a #12 AWG or a #14 AWG solid copper wire.
Figures 2–1 and 2–3 show this connection.
This wire run should be as short as possible, preferably within 5 ft.
(152 cm), not to exceed 10 ft. (305 cm), See “Approved Grounds,”
later in this chapter, for more information.
The AC outlet must be connected to the 147A protector with#12 AWG
or a #14 AWG solid copper wire.
2-10 Installing the Control Unit