AT&T System 75 Wiring Diagram page 114

Equipment Room Hardware And Cabling Installation
78 1/2 INCHES
Figure 3-17. Cross-Connect Field Installation, 66-Type Connecting
Blocks
2. Place bottom of the first backboard/connecting block on the line
and align it vertically with the left side of the switch cabinet. Mark
the mounting holes.
Remove the backboard/connecting block and drill holes in the wall
3.
for 3/4-inch No. 12 wood screws.
4. Move the backboard/connecting block into place and fasten it to
the wall with 3/4-inch No. 12 wood screws.
The next backboard/connecting block can be mounted to the right
5.
or above the one just installed, depending on space requirements.
FLOOR LINE
AC POWER
STRIP
12 INCHES
3-31