Ac power, Grounding – AT&T System 25 User Manual
Page 42
INSTALLATION
AC Power
All cabinets and any locally-connected System 25 peripheral equipment
(System Administration Terminal [SAT], Station Message Detail Recording
[SMDR] device, Digital Tape Unit [DTU]), and Customer Service Unit (CSU)
used for DS1 connections must be plugged into the common ac power outlet.
This outlet must have an associated ground block connected to an approved
building ground, using #6 AWG copper wire. (This ground block is the
system’s single-point ground.)
A 1-cabinet system requires one quad ac outlet. A 2- or 3-cabinet system
requires a second quad outlet and two separately fused 15-ampere circuits.
Additional ac outlets may be needed for auxiliary equipment. All ac outlets
must have the safety ground (green wire) cross-connected to the single-point
ground block on the first quad outlet. (See Figure 2-9.)
Local options may require that surge protectors be used for all peripheral
equipment used with the System 25, including the Customer Service Unit
(CSU).
Grounding
For proper grounding instructions, refer to the
AT&T System
25
Electrical
Protection and Exposure Check List (555-500-1 20).
Warning:
Verify that the building ground has been provided by
one of the methods listed below, that ac power uses
approved building ground for its primary ground, and
that all voltage limiting devices are grounded to building
approved ground.
Improper ground can result in
equipment failures and service outages from lightning
induced surges on the power lines.
An approved building ground for System 25 may be one of the following,
listed in decreasing order of preference:
1.
Building steel.
2. Acceptable water pipe— a metal underground water pipe at least 1/2
inch in diameter, in direct contact with the earth for at least 10 feet.
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 is connected.
A metallic underground water pipe must be supplemented by the
2-18