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Cisco Nexus 7000 System Site Preparation Guide
OL-15846-01
Chapter 2 Preparing the Site
Dust and Particles
Dust and Particles
Exhaust fans cool power supplies and system fan trays cool systems by drawing in air and exhausting air
out through various openings in the chassis. 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 th e system.
Note You can use an optional air filter if you install a Nexus 7000 series device in a nonclean environment.
In addition to regular cleaning, follow these precautions to avoid cont amination of your equipment:
• Do not permit smoking near the Nexus 7000 Series device.
• Do not permit food or drink near the Nexus 7000 Series device.
Corrosion
The corrosion of system connectors is a gradual process that can eventually lead to intermittent failures
of electrical circuits. The oil from your fingers or prol onged exposure to high temperature or humidity
can corrode the gold-plated edge connectors and pin connectors on various components in the Nexus
7000 Series devices. To prevent corrosion, avoid touching contacts on modules and protect the system
from extreme temperatures and moist, salty environments.
Electromagnetic and Radio Frequency Interference
Electromagnetic interference (EMI) and radio frequency in terference (RFI) from the Nexus 7000 Series
can adversely affect devices such as radio and television (TV) receivers operating near the system. Radio
frequencies that emanate from the Nexus 7000 Series device can also interfe re with cordless and
low-power telephones. Conversely, RFI from high-power telephones can cause spurious characters to
appear on the system monitor.
RFI is defined as any EMI with a frequency above 10 kHz. This type of interference can travel from the
system to other devices through the power cable and power source or through the air like transmitted
radio waves. The Federal Communications Commission (FCC) publishes specific regulations to limit the
amount of EMI and RFI emitted by computing equipment. Each Nexus 7000 Series device meets these
FCC regulations.
To reduce the possibility of EMI and RFI, follow these guidelines:
• Cover all open expansion slots with a metal filler.
• Always use shielded cables with metal connector shells for attaching peripherals to the system.
When wires are run for any significant distance in an electromagnetic field, interference can occur
between the field and the signals on the wires and cause the following implications:
• Bad wiring can result in radio interference emanating from the plant wiring.
• Strong EMI, especially when it is caused by lightning or radio tra nsmitters, can destroy the signal
drivers and receivers in the chassis and even create an electrical hazard by conducting power surges
through lines into equipment.