Protecting The Switch; Protecting Other Equipment - Avaya 6424D+M User Manual

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ELECTRICAL PROTECTION: SYSTEM 85 AND DEFINITY GENERlC 2 WITH TRADITIONAL MODULES
For more details on electrical protection, see Telecommunication Electrical Protection (350-060).
Riser Cable
Although riser cable (the distribution cable that stays within a building) rarely receives direct lightning
strikes, instances of risers subjected to residual voltages as high as 5000V from lightning strikes on the
buildings housing them have been observed. To protect against this type of hazard, design your riser
with a coupled bonding conductor (CBC) to protect it. Ground the shield at each closet or floor where
pairs leave the main cable. Use 6AWG wire and connect all grounds to a common ground.
Campus Cable
Campus cable (the distribution cable that is laid between buildings) is considered exposed to power
contact or induction if it shares a trench with power lines that carry more than 300 Vrms and if 12-in.
spacing between the two cannot be guaranteed. It is also considered exposed to induction if the cable
travels a long distance parallel to a power line even though it does not share the same trench. Campus
cable that is exposed to power contact is also considered to be susceptible to sneak currents. Campus
cabling may also be exposed to lightning under certain conditions.

PROTECTING THE SWITCH

System 85 and DEFINITY™ Generic 2 Communications System (hereafter abbreviated to DEFINITY
Generic 2 or Generic 2) are equipped with single-point ground lightning protection to prevent lightning-
induced surges from traveling through the power system. Single-point grounding provides for all
grounds in the communications system to originate from a single point or node on the AC protector
cabinet. If lightning strikes, the communications system avoids damage because it rises and falls in
potential with the single-point ground in response to the lightning potential. In addition, surge arresters
on the main AC power lines reduce the amplitude of the lightning-caused surges and prevent damage to
the system's AC-powered equipment.
The communications system's cabinets are grounded when they are installed. Each cabinet has a ground
for lightning and a ground for the equipment that it houses, and the grounds for each cabinet are
connected to the single-point ground for the system. A CBC connects the single-point ground of the
switch to the protector-ground terminal, which establishes a path to route lightning to ground.

PROTECTING OTHER EQUIPMENT

Three kinds of protectors are used for distribution cables, the main distribution frames (MDFs),
intermediate distribution frames (IDFs), circuit packs, and terminals: primary protectors, enhanced
primary protectors, and secondary protectors. Primary and enhanced primary protectors protect against
high voltage, and in some cases excessive current flows, by grounding the circuit. Such situations can
be caused by surges from lightning, power crosses, power induction and ground-potential rise. The
difference between the primary protector and the enhanced primary protector is that the enhanced