User Manual

Prepare the Site

Site Electrical Wiring and Cable Guidelines

When planning the electrical wiring and cabling at your site, consider the factors discussed in

the following sections.

Distance Limitations for Signaling

Improperly installed wires can emit radio interference. In addition, the potential for damage

from lightning strikes increases if wires exceed recommended distances, or if wires pass

between buildings. The electromagnetic pulse (EMP) caused by lightning can damage

unshielded conductors and destroy electronic devices. If your site has previously experienced

such problems, you might want to consult experts in electrical surge suppression and

shielding.

Radio Frequency Interference

You can reduce or eliminate the emission of radio frequency interference (RFI) from your site

wiring by using twisted-pair cable with a good distribution of grounding conductors. If you

must exceed the recommended distances, use a high-quality twisted-pair cable with one

ground conductor for each data signal when applicable.

Electromagnetic Compatibility

If your site is susceptible to problems with electromagnetic compatibility (EMC), particularly

from lightning or radio transmitters, you might want to seek expert advice. Strong sources of

electromagnetic interference (EMI) can destroy the signal drivers and receivers in the router

and conduct power surges over the lines into the equipment, resulting in an electrical hazard.

It is particularly important to provide a properly grounded and shielded environment and to

use electrical surge-suppression devices.

Fiber-Optic and Network Cable Guidelines

The router supports PICs that use various kinds of network cable, including multimode and

single-mode fiber-optic cable. For information about the type of cable used by each PIC, see

the M20 and M40 Internet Routers PIC Guide.

For more information about fiber-optic cable, see the following sections:

 Multimode and Single-Mode Fiber on page 50

 Attenuation and Dispersion on page 50

 Power Budget Calculation on page 51

 Power Margin Calculation on page 51

 Attenuate to Prevent Saturation at SONET/SDH PICs on page 53