The compilation of knowledge
acquired through information
harvesting helps to facilitate
the selection of appropriate
pathways, components, and
media with far greater certainty
of long term functional success.
the outlet types of choice. Shielded and voltage rated
RJ45-to-RJ45 patch cables will facilitate the final
connection to the end device.
• At the camera monitor location, the rigid steel conduit
will terminate within the suspended ceiling
space of the operator control room where the cable
will emerge and be fished inside one of the walls to
a commercial grade flush mounted faceplate/jack
assembly. A shielded RJ45-to-RJ45 patch cable will
be used for device connection; the shielding is a precautionary
measure due to the intensity of EMI.
Media
For this application, a non-armored, industrial grade,
F (overall foil shield), indoor-outdoor Cat 6 balanced
twisted-pair cable with 600 VAC insulation rating is the
best choice. Why? When conduit is used for the pathway
or portions thereof, armored cable is typically not
required as the conduit provides the necessary mechanical
protection and, due to the larger diameter of armored
cable, would require much larger conduit. Industrial grade
cables are specifically designed for the harsh industrial
environment, such as withstanding temperature extremes,
oil resistance and spark/weld spatter resistance. Be sure to
research these media characteristics as part of the specification
process. An indoor-outdoor rated cable should be
used wherever temperature, moisture and UV levels
mimic that of an outdoor environment, as they do in
this example. Cat 6 cable is selected because the bandwidth
34 I ICT TODAY
requirement for industrial control devices is not
a significant factor. Most devices are designed to operate
at only 10 or 100 Mb/s, so Category 6 balanced twisted-
pair is more than adequate. A 600 VAC insulation rating
should (or must, depending on local codes) be used where
communications cabling will be routed alongside power
wiring. This situation becomes most evident in brownfield
or retrofit projects where existing control panels
and media pathways must be utilized and are often not
designed with suitable segregated wiring spaces for
communications cabling.
Other details about this cable selection include
the following:
• The cables will be housed in rigid steel conduit where
it is most subject to mechanical damage, so no overall
cable armor is required.
• The cables will be routed through open cable trays
where they could encounter abuse as other cables are
added or removed in the future, so an industrial grade
high density polyethylene (HDPE) jacket is advisable.
• A screened (overall foil shield) is a necessity, since
they will be routed in parallel with other power cables
through the existing cable trays, even though there is
a physical barrier between them. The foil shield is also
required primarily due to the exposure to intense EMI
where the cables are outside of the rigid steel conduits.
• Because the cables will be exposed to sunlight through
exterior building doors that remain open in warmer
months, temperature extremes and hot/cold transitions
can occur. There could also be condensate
(e.g., typically control room to factory floor and
control panels to factory floor).
• Since most industrial devices operate at 100 Mb/s
(maximum 1Gb/s) for the foreseeable future, Cat egory
6 balanced twisted-pair suffices for now. Most industrial
networks have the need for low latency but do
not have high-bandwidth requirements.
• Since the control panels are existing and were not
purpose-built to incorporate segregated pathways
for low voltage/communications cabling, the
designer/installer may need to route them within the
same plastic wiring ducts as other power and control
wiring. It is mandatory per NEC/CEC that the cable