AT&T System 75 Wiring Diagram page 261

CHAPTER 4. STATION WIRING
Trunk/Auxiliary Field Connections—Telephone Used for Emergency
Transfer and as a Normal Extension
Connect telephone as follows:
At trunk/auxiliary cross-connect field, connect a pair of wires between
the -48V and GRD terminals on the yellow emergency transfer
row/connecting block and the EM TRANS RELAY PWR terminal (Figures
4-33 and 4-34, respectively for 110-type and 66-type hardware).
1. Connect CO trunk leads from the purple field to TC terminals on the
yellow emergency transfer row/connecting block for each trunk.
2.
Connect CO trunk leads from the green field to TK terminals on the
yellow emergency transfer row/connecting block for each trunk.
3. Connect telephone leads from the purple analog line board
row/connecting block to the LC terminals on the yellow emergency
transfer row/connecting block for each telephone.
4. Connect ST leads on the yellow emergency transfer row/connecting
block for each emergency transfer telephone to the ST terminal
appearance in the purple trunk/auxiliary cross-connect field.
5. Connect the ST leads from the terminal selected in Step 4 to the
assigned terminal in the blue or white station distribution field.
If ground start is required, connect two wires from the ground
6.
terminals to the third pair of each emergency telephone appearance
on the yellow trunk/auxiliary row created in Step 5. Loop the wires
from the first appearance through to the last appearance if enough
ground terminals are not (Figure 4-37).
4-64