Samsung OfficeServ 7400 Technical Manual page 9

OfficeServ 7400
TECHNICAL MANUAL
grounded item that is permanently and reliably connected to the electrical service
equipment ground.
Bare, covered, or insulated grounding conductors are acceptable. A covered or
insulated grounding conductor shall have a continuous outer finish that is either green
or green with one or more yellow stripes.
Failure to provide an adequate ground may cause a safety hazard, confusing trouble
symptoms or even circuit card failure.
WARNING: Unplug the power cord from the AC outlet before attempting to connect
the ground. Hazardous voltage may cause death or injury. Observe extreme caution
when working with AC power. Remove lines from trunk cards.
What the above paragraphs mean is that when conventional analog telephone circuits
are connected to the OfficeServ 7400 system, under fault conditions (i.e., the tip and/or
ring conductor is crossed with a power line, or the circuit is affected by lightning during
a storm), it is possible for hazardous potentials to appear across the tip and ring wiring
coming into the OfficeServ 7400 cabinet(s) from the outside plant (i.e., overhead
cables, buried cables, cable head pedestal). These circuits are provided with both
primary and secondary protection circuitry which will attempt to drain off these high
voltages and currents to earth ground. Obviously, it is important to have a good source
of ground connected to the OfficeServ 7400 system to drain this energy off. Again, a
good earth ground source is required by the OfficeServ 7400 system.
The OfficeServ 7400 system has two ground reference points. One point is via the
green wire in the power cord connected to the AC power outlet. This ground
connection is provided to meet local electrical codes when the AC ground is required
to be common with the earth ground. However, this can be disconnected either
intentionally or unintentionally. Consequently, a more permanent ground connection is
required by connecting a high current/voltage capacity ground wire which is bonded to
ground at the electric service power entrance or via some other method approved by
the National Electrical Code to the OfficeServ 7400 system ground lug. This is a more
secure ground connection, which can only be disconnected intentionally. These
precautions are taken for safety reasons to protect personnel working on the OfficeServ
7400 system and also for operational reasons to accommodate ground return and/or
ground-referenced analog telephone circuits, which require this solid earth ground
connection for normal functioning.
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INSTALLATION
PART 1 JUNE 2006