Cisco Systems Cisco 12816 Manuale Utente

Site wiring is unlikely to emit radio interference if you use twisted-pair cable with 
a good distribution of grounding conductors. Use a high-quality twisted-pair cable 
with one ground conductor for each data signal, when applicable.

Give special consideration to the effect of a lightning strike in your vicinity, 
especially if the wiring exceeds the recommended distances, or if it passes 
between buildings. The electromagnetic pulse (EMP) caused by lightning or other 
high-energy phenomena can easily induce enough energy into unshielded 
conductors to destroy electronic devices. If you have experienced EMP problems 
in the past, you may want to consult experts in electrical surge suppression and 
shielding.

Most data centers cannot resolve the infrequent but potentially catastrophic 
problems without pulse meters and other special equipment. In addition, these 
problems can take a great deal of time to identify and resolve. We recommend that 
you take the necessary precautions to avoid these problems by providing a 
properly grounded and shielded environment, with special attention to issues of 
electrical surge suppression.

This section contains detailed cabling and signal information for all interface and 
port connections to the GRP. It also provides information for Ethernet routing and 
equipment.

Ports labeled Ethernet, 10BASE-T, Token Ring, Console, and AUX are safety 
extra-low voltage (SELV) circuits. Only connect SELV circuits to other SELV 
circuits.