Instruction manual

ENVIRONMENTAL REQUIREMENTS
● Surge protection on the AC power to System 25 and associated equipment (SAT,
SMDR, DTU, etc.) provided by the TII 428 Unit.
The protection outlined above is adequate for more than 99 percent of all lightning strikes.
For the few remaining cases, external secondary protection, located at the trunk access area
of the cross-connect field, can be employed.
Several commercially available units can be
used. If 66-type block terminations are used, a very convenient device is the LP3-230-220
Fused Lightning Protector manufactured by ITW-LINX, 195 Algonquin Road, Des Plaines,
Illinois 60016. This unit plugs into the 66-block (in place of the shorting bars) and includes
the sneak current fuse. One unit is required per protected pair. A ground bar is provided
with the lightning protection units or can be ordered separately (Comcode 901007120). Porta
Systems is another supplier of surge protection devices.
Regardless of the type installed, all
lightning protectors located in the cross-connect area must be grounded to System 25’s SPG
via a No. 6 AWG copper wire.
Transmission facilities (voice pairs) that extend out-of-building and are not included in the
network interface may be installed by the TelCo or through other means (for example, by the
building owner and/or the property owner).
These facilities, aerial or buried, must be
protected with voltage limiting devices and sneak current fuses. The only exception to this
rule is buried cable less than 140 feet long that is enclosed in a continuous metallic conduit
from one building entrance to the other. The conduit must be connected to an approved
building ground at each end.
If single-line sets are extended out-of-building, primary protection devices for voice pairs
should be used. If MERLIN Communications System voice terminals are extended out-of-
building, the facilities must be protected with the TII Model 341 (PEC 32918, Comcode
403865785) at each end.
Terminals J1-3 and J1-6 of the Model 341 should not be
connected. Maximum distance between a MERLIN System voice terminal and the System 25
cabinet is 2000 feet. There is no limit on how much of the 2000 feet can be out-of-building.
However, out-of-building stations cannot be powered over the line; they must be powered
locally using PEC 62510.
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