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EXPOSED PORT PROTECTION
and 2,200 feet when using 26 AWG wire. The range can be extended to 5,000 feet (24 AWG) or
4,000 feet (24 AWG) with the use of a Data Link Protector (DLP). The DLP is an isolating
transformer used to remove phantom power on the switch side and reintroduce it on the terminal
side. When a DLP is used, the voice terminal must be locally powered by an external power sup-
ply or through the AC power cord provided with some of the 7400 series voice terminals. The
DLP is installed on the equipment side of the protection in both buildings. In high lightning areas,
the DLP may also be installed to provide the maximum degree of protection and reliability.
Table A shows the recommended protectors for the DEFINITY G1, G2, G3, System 75, and Sys-
tem 85. Table B shows the in-range, out-of-building (IROB) protection for DEFINITY line circuits
and terminals.
Caution: The following circuit pack and terminal arrangements are not allowed to be
installed in an exposed environment:
1. 7300 Series connected to the TN762B or ANN17 Circuit Pack
2. MET terminals connected to the TN735 Circuit Pack
3. Analog terminals connected to the TN746 Circuit Pack
TABLE 2-C. Recommended Protectors
PRIMARY ENHANCED
PRIMARY
(w/Heat Coil) PRIMARY
SECONDARY
3B1A 4B1C 4C3S-75 79A Fuse
(carbon) (carbon) (solid state)
3B1E-W 4B1E-W ITW Linx SCP-1
(wide-gap (wide-gap (gas tube
gas tube) gas tube) avalanche suppress)
3C1S 4C1S
(solid state) (solid state)
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