type, strand count, and cable construction. If the
physical infrastructure may potentially be joint use,
it is recommended to use singlemode (OS1/OS1a/OS2).
If for industrial use only and required lengths do not
exceed 500 meters (approximately 1,640 feet), multimode
(OM3/OM4/OM5) may suffice. The strand count
is determined by the redundancy level and the number
of distribution or access level switch links it must support;
if there are multiple switches, should they employ
stacking technology or does each one require a dedicated
fiber uplink? Each link between switches requires two
strands of optical fiber, so redundant switch links require
a total of four strands.
To determine the appropriate cable construction, the
questions and selection criteria pattern should be similar
to the following:
1. Will this cable need to pass through a plenum space,
which is the space above a suspended ceiling, that is
used as a return air plenum for the HVAC system?
• If yes, then specify a cable that is approved
by the authority having jurisdiction for use
in a plenum space. This might be a plenum
or low smoke zero halogen (LSZH) cable.
• If no, then a riser rated cable may be used.
2. Will it travel outdoors or otherwise be exposed
to temperature and/or humidity extremes?
Consider the fact that the cable may technically be
indoors, but it may travel from an environmentally
28 I ICT TODAY
controlled to an uncontrolled space. Be aware that
the plant floor may not be environmentally controlled
and, therefore, should be categorized as an outdoor
space. The goal is to keep moisture out of the cable.
If there are temperature and/or humidity extremes,
use an indoor-outdoor rated cable.
3. Is there a potential for rodent damage?
• If yes, specify an armored cable or route it
through a continuous metallic conduit.
4. Does the client have stipulations on pathway types
(e.g., conduit, cable tray, independently supported
along the building structure)?
• If in conduit, a non-armored cable is sufficient.
• If in a cable tray, and there is potential for
physical damage or independently supported
along the building structure, an armored cable
is best suited.
• If armored cable is best suited, will the cable be
exposed to any water or moisture? If so, specify
an indoor-outdoor armored cable with an overall
waterproof jacket that is often referred to
as Teck cable.
5. Can pathways be established that will not interfere
with factory floor production when moves, adds,
and changes are required?
• If no, then consider using conduits with pull
points located in areas that are accessible without
disrupting production. For optical fiber, consider
using a blown fiber solution.
When considering the above criteria, the most versatile
cable construction for industrial use is an indoor-outdoor,
plenum rated, armored cable with an overall waterproof
jacket. However, it is also the most costly cable construction,
so it may not be justifiable if the environment does
not require it or if conduit pathways are utilized.
ACCESS LEVEL INFRASTRUCTURE:
ACCESS SWITCH TO AN END DEVICE
Although balanced twisted-pair remains the typical media
choice for the plant floor device connections, plastic
optical fiber (POF) and wireless are also deployed to suit
specific applications. Please note that plastic optical
fiber is not currently a recognized media type within
Since the logical designs denote
the base requirements of the
physical design, the intended
logical topologies and level
of redundancy between each
of the associated network levels
(i.e., core, distribution, access,
and device) must be identified.