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DEFINITY Enterprise Communications Server Release 6
Installation and Test for Multi-Carrier Cabinets
555-230-112
Issue 5
May 1998
Install and Wire Telephones and Other Equipment
Page 5-33Off-Premises or Out-of-Building Stations
5
Carbon block, or equivalent protection is required at both building entrances.
Also sneak current protection is required. Protection can be provided by a 4-type
protector or a 3-type protector plus a separate sneak current protector. The
4-type protector is equipped with a heat coil.
The 4-type protector is the preferred device. For installations not using primary
protection, 4-type protectors should always be used. When the 3-type protector
is already installed, a separate sneak current protector is required. The multi-pair
protector units and the off-premises cabling must be locally engineered.
Connectorized multi-pair protector units (female 25-pair connector) are
recommended. Table 5-11
shows the recommended protectors.
The maximum range of out-of-building analog telephones (500-, 2500-, or
7100-types) connected to an analog line circuit pack should be such that the
maximum loop resistance does not exceed 1300 ohms.
The following voice terminals/telephones cannot be installed in an exposed
environment:
■ 7300-type voice terminals connected to TN762 Hybrid Line circuit packs
■ Multi-button Electronic Telephone (MET) sets connected to TN735 MET
Line circuit packs
■ Analog telephones connected TN746 Analog Line circuit packs
1. The 3-type protectors should only be used if they are already part of the
existing protection system. A sneak current protector is always required when
a 3-type primary protector is used.
2. The 3-type protectors should only be used if they are already part of the
existing protection system. A sneak current protector is always required when
a 3-type primary protector is used.
Table 5-11. Analog Line Circuit Protectors
Protectors
Primary
1
Primary
(with heat coil)
Sneak Current
Protectors
2
3B1A (carbon) 4B1C (carbon) 220029 Fuse
3B1E-W
(wide gap gas tube)
4B1E-W
(wide gap gas tube)
SCP-1
3C1S
(solid state)
4C1S
(solid state)