Z1A Power Failure Transfer Unit - AT&T 75 Wiring Manual

Voice Terminal Installation
12. Connect voice terminals to the information outlets.
Installation—Optional DID Make-Busy Trunk
1. Run and connect jumper from one DID make-busy lead to COM3 terminal on the
yellow emergency transfer connecting block (see Figure 4-68).
2. Run and connect jumper from the other DID make-busy circuit lead to NC3
terminal (first appearance) on the yellow emergency transfer connecting block.
Figure 4-68. Connections at Trunk/Auxiliary Field for Optional DID Make-Busy
Trunk—574-5 Power Transfer Unit

Z1A Power Failure Transfer Unit

Figure 4-69 shows wiring required at the Trunk/Auxiliary Field for a voice terminal used
only for emergency transfer. Figure 4-70 shows wiring required at the Trunk/Auxiliary
Field for a voice terminal used for emergency transfer as well as a normal extension.
If a Z1A Emergency Transfer Unit is used with central office trunks that require ground
start, a ground start switch must be installed on each emergency transfer terminal. System
ground is provided on the twenty-fifth pair of leads on each purple connecting block
associated with a switch cable when a cable is installed. System ground is connected to the
third pair of the 3-pair terminal appearance. This pair becomes the second pair at the
information outlet. A ground start switch is mounted on the side of the terminals and is
wired to ground and to the ring lead inside the terminal.
66-TYPE HARDWARE
4-105