Network Design Considerations 2-13
SIMATIC TIWAY I Series 500 NIM User Manual
Local Line Cable Installation (continued)
Cable routing should be planned as if the path between all stations on the
network were free of obstructions. Next, modify the first routing to account
for obstructions, then calculate the amount of cable needed.
!CAUTION
All local and national electrical and fire codes should be observed when
installing wiring.
Failure to observe coding requirements could result in electrical or fire hazards.
In general, there are three types of network cabling routes:
•Under-floor
•In-ceiling
•Surface ducting
Any choice of these three routes may be used on a single network. The
choice is often determined by whether the building (or buildings) in which
the network is being installed is new construction, or is an existing building.
The following paragraphs describe some of the advantages and
disadvantages of each type of cable routing.
Under-floor Routing. For under-floor routing, the cable can be enclosed
within ducts or, with raised flooring, in the “open air.” Under-floor systems
enclosed in ducts are usually expensive, and while they are better-protected
against unauthorized taps than are “open air” systems, they often make
future expansion of the network more difficult and expensive.
“Open air” under-floor cabling systems usually provide good access and
allow maximum network expansion and flexibility.
In-ceiling Routing. For in-ceiling routing, network cables are usually
supported in troughs or with hooks and clamps every 10 or 15 feet.
In-ceiling installations provide flexibility, usually cost less, and provide easy
access.
In-ceiling cable networks are not always practical. In-ceiling installations
can be difficult and sometimes dangerous in areas without drop ceilings (or
that have unusually high ceilings). Also, closed ceiling systems usually trap
dust and other debris, which makes cable maintenance difficult.
Cable Routing