Many industrial spaces, though
technically inside, are not environmentally
controlled and are subject to temperature
and humidity extremes that can be more
severe than outdoor installations.
March/April 2019 I 23
Although this is the best solution,
it is not always practical or feasible.
It can be a daunting task to
determine all these potential
difference values, and industrial
environments can also be very
dynamic with electrical system
changes. As machines and equipment
are moved, added, replaced,
and upgraded, just one of these
changes can immediately change
potential differences previously
identified and have a detrimental
effect on the integrity of the
communications infrastructure.
Since shielded cabling solutions
are more susceptible to detrimental
effects from this scenario, industry
installers use a single ended bonding
technique that has proven successful
for mitigation. The cable shields are
bonded at their source and isolated
at their destination. Although this is
not technically standards compliant,
it offers a viable and proven solution
to this issue. If this method is chosen,
there are further considerations when
selecting infrastructure system
components. Specify a patch panel
that is designed for shielded cabling
and stipulate that each patch panel
must be individually bonded to the
rack bonding busbar with a #12AWG
copper conductor. If using a modular
solution, specify shielded modular
jacks for all shielded cables
terminating at these patch panels.
Specify unshielded jacks for the
device/field ends and that heat
shrink tubing be installed to
maintain shield isolation. Most
IP- enabled end devices have
shielded ports, so it may be
necessary to specify a voltage rated
and shielded patch cable to connect
the end device to the jack outlet,
depending on whether it needs
to run in close proximity to or share
a wire way with power wiring within
the enclosure. This patch cord will
then attain a single ended bond
through the shielded jack in the
equipment, but it will remain
isolated where it connects to the
unshielded jack, thus protecting
the integrity of the single ended
bonding solution while every
section of noise susceptible cable
remains effectively shielded.
Following are some examples of
critical design information needed
for specific environment types:
Food & Beverage
• Are areas washed down
regularly?
• Are there food safety
regulations that prohibit the
use of typical infrastructure
support components?
• Are there food safety or
corporate standards that dictate
the type and material for
pathways and enclosures used
within the facility?
Conduit example: schedule
40 stainless steel
Cable tray example:
non-ventilated (solid),
aluminum, with cover
Enclosure example: NEMA 4X,
non-metallic, with sloped top.
Gas and Oil, Grain Handling,
Chemical Processing, Painting,
and Waste Water
All of these facilities include
hazardous areas as defined by
NEC/CEC, which are classified
using a Class & Division or
a Zone rating system.
• Which areas hold a hazardous
designation as specified in the
NEC/CEC?
• What are the physical
boundaries of the
classified area(s)?
• Are any telecommunications
outlets required in these areas?
• Is air purging for enclosures
an option? If so, it is typically
acceptable only if the purge is
monitored and includes a safety
shutdown feature in the event
that purge pressure is lost.
• NEC/CEC compliant pathways,
enclosures, outlet/terminations,
and devices must be part
of the infrastructure when
terminating in or passing
through any hazardous area.