Allied Telesis IE340 Series, Руководство по установке, Страница: 61 / 136

Chapter 2: Beginning the Installation
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Requirements, when connected to powered devices that are not
grounded to the same grounding conductor at the service entrance
as the switch.

Electromagnetic interference might occur between switches and
other devices when multiple switches are powered by a single DC
power supply. This can be addressed by installing clamp-on ferrite
beads on the DC power cables, between the DC power supply and
switches.

Recommendations for ground resistivity are given in Table 10.

The twisted pair cabling should not be exposed to sources of
electrical noise, such as radio transmitters, broadband amplifiers,
power lines, electric motors, and fluorescent lights.

Allied Telesis recommends using CAT6 STP or UTP for LAN ports.
These cables provide higher protection from radio frequency
interference.

Outdoor installation requires adequate electromagnetic immunity
due to the higher thread-level conditions. For guidelines, refer to
“Installing the Switch in an Outdoor Environment” on page 83.

The spaces between the SFP transceiver slots and adjacent
copper ports are small, making it difficult to disconnect cables.
Refer to Figure 13. For this reason, Allied Telesis recommends
leaving the adjacent copper port
unused
when using an SFP slot.
Be aware of the space issue and use a flat tool when removing the
port cable if you use both an SFP slot and its adjacent copper port.
Table 10. Ground Resistivity Recommendations
Level Recommendation
Best Practice <5 ohms
Acceptable 5 to 15 ohms
Marginal 15 to 25 ohms
Non-compliant >25 ohms