Connecting The Stations
Connections between the telephone stations and the common equipment station boards are typically via type
66M-xx connector blocks that are cable connected to 50-pin male connectors on the station boards.
The maximum distance allowed from the common equipment to the industry-standard telephone varies with the
gauge of wire that you use to make the connection. Refer to the following chart for complete details.
Station Type
Wire Gauge
20 AWG
22 AWG
24 AWG
Industry-Standard
Telephones
4000 Feet
3500 Feet
3000 Feet
The maximum distances stated above are dependent upon the following conditions:
•
resistance of industry-standard telephone (per EIA specs) cannot exceed 300 ohms maximum,
•
DC load resistance of the wiring between the common equipment and the industry-standard telephone plus
the DC resistance of telephone itself cannot exceed 460 ohms maximum.
If spare conductors exist in the cables that you run between the station boards and the 66M-xx connector blocks, it
is a good practice to connect the spare conductors to earth ground. Doing this may help prevent the spare
connectors from inducing radio frequency and/or AC interference into the system.
Remember, you should snap a ferrite collar around each station cable to provide protection against radio
frequency interference.
NOTE: The polarity between the individual wires in a particular voice pair is not critical.
8 – Installing The IST Board
IMI89–268
Installing The IST Station Board
