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Chapter 2
Preparing for Installation
Dust and Contamination
Chassis fans cool power supplies and systems by drawing in air and exhausting air out through various
perforations in the chassis cover. However, fans also ingest dust and other particles, causing contaminant
buildup in the system and increased internal chassis temperature. A clean operating environment can
greatly reduce the negative effects of dust and other particles, which act as insulators and interfere with
the mechanical components in the system. In addition to regular cleaning, follow these precautions to
avoid contamination of your equipment:
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•
Corrosion
Corrosion of system connectors is a gradual process that can eventually lead to intermittent failures of
electrical circuits. The oil from a person's fingers or prolonged exposure to high temperature or humidity
can corrode the gold-plated edge connectors and pin connectors on various components in the system.
To prevent corrosion, avoid touching contacts on boards and cards, and protect the system from extreme
temperatures and moist, salty environments.
Electromagnetic and Radio Frequency Interference
When wires are run for any significant distance in an electromagnetic field, interference can occur
between the field and the signals in the wires. This fact has two implications for the construction of plant
wiring:
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To predict and remedy strong EMI, you may also need to consult experts in radio frequency interference
Note
(RFI).
If you use twisted-pair cable in your plant wiring with a good distribution of grounding conductors, the
plant wiring is unlikely to emit radio interference. If you exceed the recommended distances, use a
high-quality twisted-pair cable with one ground conductor for each data signal where applicable.
If wires exceed recommended distances, or if the wires pass between buildings, give special
consideration to the possibility of a lightning strike in your vicinity. The electromagnetic pulse caused
by lightning or other high-energy phenomena can easily couple enough energy into unshielded
conductors to destroy electronic devices. If you have had problems of this sort in the past, you may want
to consult experts in electrical surge suppression and shielding.
Category 5e and Category 6 cables can store large levels of static electricity because of the dielectric
Caution
properties of the materials used in their construction. Always ground the cables (especially in new cable
runs) to a suitable and safe earth ground before connecting them to the system.
OL-8900-03
Do not permit smoking anywhere near the system.
Do not permit food or drink near the system.
Bad wiring practice can result in radio interference emanating from the plant wiring.
Strong EMI, especially when it is caused by lightning or radio transmitters, can destroy the signal
drivers and receivers in the system chassis, and can even create an electrical hazard by conducting
power surges through lines and into equipment.
Cisco ME 6500 Series Ethernet Switch Installation Guide
Site Requirements
2-5
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