Installing Taps - Allen-Bradley 1779-KFMR User Manual

Chapter 3
Installing Cabling Hardware for
the Data Highway II Link

Installing Taps

3 10
Planning Cable Routing
Follow these cable routing recommendations for protecting the coaxial
cable from electrical interference:
If the cable must cross power feed lines, it should do so only at right
angles.
Keep the cable at least 1 foot from 120V AC power lines, 2 feet from
240V AC power lines, and 3 feet from power lines of 480V AC or
more.
Keep the cable at least 3 feet from any electric motors, transformers,
rectifiers, generators, arc welders, induction furnaces, or sources of
microwave radiation.
Conduits
Conduits provide protection from physical damage as well as an
additional layer of protection from electrical interference for a coaxial
cable. Route the trunkline cable through conduit for the first 20 feet
above the enclosure. Where you route the coaxial cable through conduits,
follow these additional recommendations.
Use ferromagnetic conduit near the greatest sources of electrical
interference. You can use aluminum conduit in non-critical areas.
Couple between aluminum and ferromagnetic conduits with plastic
connectors. Make an electrical connection around the plastic connector
to hold both sections of the conduit at the same potential.
The entire length of the conduit should be grounded. Ground the
conduit by attaching it to the steel structure of the building.
Do not let the conduit touch the tap or the plug on the cable.
This conduit should only contain serial communication cables. Cables
within the conduit should be loosely arranged.
The tap has a metal shell which electrically connects to the outer
conductor of the coaxial cable. Therefore, the mounting base of the tap is
made of plastic to insulate the metal shell from ground. However, the cap
for the dropline jack hangs down on a chain. Be sure to mount the tap so
that the cap and its chain hang freely without touching a conductive
surface. If the metal shell, cap, or chain touches a conductive surface, the
reliability of the link could be significantly reduced.
If you do not have a node interface to connect to the tap, place the cap
over the dropline jack on the front of the tap (Figure 3.12). In this case,
store the dropline so that it will be available later when you install a node
interface.