Issue link: https://www.e-digitaleditions.com/i/1192126
34 I ICT TODAY 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 con- duit 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 pre- cautionary 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 path- way or portions thereof, armored cable is typically not required as the conduit provides the necessary mechani- cal 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 specifica- tion 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 band- width 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 brown- field 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 transi- tions 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 indus- trial 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