System Grounding - Cisco Catalyst 6807-XL Hardware Installation Manual

System Grounding

Besides these appliances, the greatest threats to a system's power supply are surges or blackouts that are caused
by electrical storms. Whenever possible, turn off the system and peripherals, if any, and unplug them from
their power sources during thunderstorms. If a blackout occurs—even a temporary one—while the system is
turned on, turn off the system immediately and disconnect it from the electrical outlet. Leaving the system on
may cause problems when the power is restored; all other appliances left on in the area may create large
voltage spikes that may damage the system.
System Grounding
You must install a system ground as part of the chassis installation process. Chassis installations that rely only
on the AC third-prong ground are insufficient to adequately ground the systems.
Proper grounding practices ensure that the buildings and the installed equipment within them have
low-impedance connections and low-voltage differentials between chassis. When you install a system ground,
you reduce or prevent shock hazards, chances of equipment damage due to transients, and the potential for
data corruption.
Without proper and complete system grounding, you run the risk of increased component damage due to ESD.
Additionally, you have a greatly increased chance of data corruption, system lockup, and frequent system
reboot situations by not using a system ground.
Installations that rely solely on system grounding that uses only an AC third-prong ground run a substantially
Caution
greater risk of equipment problems and data corruption than those installations that use both the AC
third-prong ground and a properly installed system ground.
The following table lists some general grounding practice guidelines.
Table 8: Grounding Practice Guidelines
Environment
Commercial building is subjected to
direct lightning strikes.
For example, some places in the United
States, such as Florida, are prone to
more lightning strikes than other areas.
Commercial building is located in an
area where lightning storms occur
frequently, but is not prone to direct
lightning strikes.
Commercial building contains a mix
of information technology equipment
and industrial equipment, such as
welding.
Cisco Catalyst 6807-XL Switch Hardware Installation Guide
20
Electromagnetic Noise Grounding Recommendations
Severity Level
High All lightning protection devices must be
installed in strict accordance with
manufacturer recommendations.
Conductors carrying lightning current
should be spaced away from power and
data lines in accordance with applicable
recommendations and codes. Best
grounding practices must be closely
followed.
High Best grounding practices must be closely
followed.
Medium to High Best grounding practices must be closely
followed.
Preparing for Installation
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