Site Wiring Distance And Interference Guidelines; Electromagnetic Interference; Distance Limitations For Signaling And Unshielded Conductors - Cisco 10720 - Internet Router Installation And Configuration Manual

Environmental Safety Guidelines
The following guidelines will help to ensure safety and protect the equipment. This list does not include
every potentially hazardous situation, so be alert.
A Cisco 10720 Internet Router configured with the dual DC-input power supply should have a readily
accessible disconnect device incorporated for fixed wiring.
See the
Caution For safety, periodically check the resistance value of the antistatic strap. The measurement should be
between 1 and 10 megohms (Mohms).
A readily accessible two-pole disconnect device must be incorporated in the fixed wiring.
Warning
Statement 91

Site Wiring Distance and Interference Guidelines

This section offers site wiring guidelines for setting up the site plant wiring and cabling. When planning
the location of the new system, consider the following:
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Electromagnetic Interference

Electromagnetic interference (EMI) can occur between the field and the signals on the wires when the
wires are run for any significant distance. This fact has two implications for the construction of plant
wiring:
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•
A good quality twisted pair cable or shielded twisted pair cable helps limit radiation and noise induced
into the cable, minimizing the potential for the following:
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Distance Limitations for Signaling and Unshielded Conductors

You must give special consideration to the effect of a lightning strike in the site vicinity if wires exceed
recommended distances, or if wires pass between buildings. The electromagnetic pulse (EMP) caused
by lightning or other high-energy phenomena can easily couple enough energy into unshielded
conductors to destroy electronic devices.
Cisco 10720 Internet Router Installation and Configuration Guide
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"Safety Guidelines" section on page 2-2
Electromagnetic Interference, page 2-10
Distance Limitations for Signaling and Unshielded Conductors, page 2-10
Poor 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 and/or cause
interference with the signal drivers and receivers in the router, and can create an electrical hazard by
conducting power surges through lines and into equipment.
To predict and remedy strong EMI, consult experts in radio frequency interference (RFI).
Note
Radio interference
Interference with the data transmission
Chapter 2
for additional information.
Preparing for Installation
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