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Description
Page 49 of 290
Line cards
Description
Two line cards, the NT1R20 Off-Premise Station Line Card and the QPC192
Off-Premise Extension Line Card, have built-in protection against lightning
strikes and power line crosses. These should be the preferred cards for an
off-premise application. Some of the other cards can be used when external
line protectors are installed.
When using the line-side T1 card for an off-premise or network application,
external line protectors must be installed. Install an isolated type channel
service unit (CSU) as part of your terminal equipment to provide the
necessary isolation and outside line protection. The CSU should be an FCC
part 68 or CSA certified unit.
Line protectors
Line protectors are voltage-absorbing devices that are installed at the
cross-connect terminals at both the main building and the remote building.
The use of line protectors will ensure that system and telephone components
are not damaged from accidental voltages that are within the limit of the
capacity of the protection device. Absolute protection from lightning strikes
and other stray voltages cannot be guaranteed, but proven cases have shown
that the use of line protection devices significantly reduces the possibility of
damage.
Nortel Networks has tested line protection devices from three manufacturers
(see Table 6). Each manufacturer offers devices for protection of digital as
well as analog telephone lines.
These devices are compatible with 66 type M1-50 split blocks or equivalent.
Consult the device manufacturer if more specific compatibility information is
required.
Line protection grounding
In conjunction with line protectors, proper system (PBX) grounding is
essential to minimize equipment damage. Nortel Networks recommends that
you follow the grounding connection requirements as described in
Meridian 1 system installation procedures (553-3001-210). This requirement
includes connecting the ground for the protection devices to the approved
building earth ground reference. Any variances to these grounding
requirements could limit the functionality of the protection device.
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