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Install Off-Premises Station Wiring
Issue 10 June 2005 137
When possible, all new and reused wiring installations should use blocks that accept the
standard 5-pin plug-in 4C3S-75 protector. However, this may not be cost-effective in some
cases. For these installations, the ITW Linx protector may be installed. An example of this is
where screw-type carbon block protectors (or other non plug-compatible types) are in place and
it is too costly to re-terminate the outside plant cable on a 5-pin mounting block for only a few
out-of-building terminals.
The ITW Linx Enhanced Protector may be installed in series with existing primary protection.
Note the 4C3S-75 protector cannot be installed in series with other types of primary protection.
It must be installed as the only protection on the line entering the building. For the 4C3S-75
protector, various 25-, 50-, and 100-pair protector panels are equipped with 110-type connecting
blocks and/or RJ21X connectors. The ITW Linx Enhanced Protector mounts directly on
connecting blocks and requires a separate ground bar.
The maximum range for out-of-building digital voice terminals is 3400 feet (1036 m) when using
24 AWG (#5) (0.26 mm
2
) wire and 2200 feet (670 m) when using 26 AWG (#4) (0.14 mm
2
) wire.
The range can extend to 5000 feet (1524 m) using 24 AWG (#5) (0.26 mm
2
) wire or 4000 feet
(1219 m) using 26 AWG (#4) (0.14 mm
2
) wire with the use of a data link protector. The protector
is an isolating transformer used to remove phantom power on the system side and re-introduce
it on the terminal side.
When a protector is used, the voice terminal must be locally powered by an external power
supply or through the AC power cord provided with some of the 7400-type voice terminals. The
protector is installed on the equipment side of the protection in both buildings.
Refer to Table 4: Comcodes for CMC1
on page 31 for circuit protector and data link protector
comcodes.
Table 24: Digital Voice Circuit Protectors
Circuit Pack Enhanced Primary Protector
(With Sneak Current
Protection)
TN754 V13 or earlier ITW Linx Only
TN754 V14 or later 4C3S-75 or ITW Linx
TN754C all vintages 4C3S-75 or ITW Linx
TN2181 4C3S-75 or ITW Linx
TN2224CP 4C3S-75 or ITW Linx