British Telecommunications (BT) Senator, System Manual

Page: 19 / 75

2.6
EXCHANGE LINE
AND EXTENSION
WIRING
Exchange
Line
Earth
(If required)
Spare
EXCHANGE LINE
CPE/MS
526
Issue
2 (12/88)
Part 2 INSTALLATION
The cables bringing exchange lines and extension connections to the CCU
should be fed under the rear mounting plate to enter the CCU through the
slot in the bottom right-hand comer, see Fig
2.5.
All extensions must use
'twisted pair' type cable: Cable Equipment
2503F (6
wire). All cables are
terminated on insulation displacement connections using an Inserter Wire
2A.
The cable should be run directly to the Line Jack from the Senator Back
Plane. The two spare wires should be insulated and must not be used to
connect other circuits, unless otherwise specified.
Terminate the exchange lines and extensions on all appropriate connector
blocks. These are labelled on the PCB.
Note that exchange line blocks have three terminals, these being
A
and B
wires and Earth (used for PBX recall). Extension blocks have four terminals,
A
and B being the speech pair, C and
D
the data pair. The data pair and
speech pair must not be transposed nor must the data pair be reversed wire
for wire.
0-W
D
Data
Pair
W-0
c
W--B
A
Speech
Pair
B
EXTENSION
Fig 2.8 TERMINATION OF EXCHANGE LINE AND EXTENSION
CABLES.
The cables at each extension should be terminated onto an LJU No
... ./3A.
(see diagram over).
2.11