Issue link: https://www.e-digitaleditions.com/i/1192126
28 I ICT TODAY 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), multi- mode (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 sup- port; 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 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 construc- tion, 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.