Issue link: https://www.e-digitaleditions.com/i/1327492
30 I ICT TODAY Can legacy cabling be used for these applications? For operation at speeds of 2.5G and 5G, The NBASE-T Alliance has developed methods to do just that by installing upgraded WAPs in brownfield cable plants. It should be noted, however, that these installations are susceptible to length and bundling restrictions; as seen in Table 2, reliability may decrease for some cables at longer distances. To get full bandwidth from WAPs for these applications, therefore, it is always recommended to use Cat 6A cable. While brownfield cable plants may test well on day one, the user may experience greater alien crosstalk from neighboring cables. As bundling and distance start to impact the performance of the cable driving the access point, the WAP will auto-negotiate to a lower bandwidth, negating its high bandwidth benefits. So, while retrofitting is an option, it is recommended that users install new Cat 6A cable at the same time as the new WAPs in order to take advantage of the higher power and bandwidth offered by these devices. PoE CABLES AND HEAT RISE As evolving PoE standards push more power through the network, higher temperatures in the cabling plant become a concern. As mentioned, the latest generation of PoE, Type 4, can supply up to 100W—more than three times that of Type 2 PoE. At the same time, the market is seeing a much larger number of IoT devices installed for such applications as access control and security cameras. The increased density of high-wattage devices relying on cables in confined spaces (e.g., inside walls and above ceilings) can cause overheating in cable bundles. How does this impact performance? Recently, UL and some industry members conducted a study on the effect of higher power loads and heat rise on category cables in these applications. This was the first comprehensive study of how a category cable performs at higher PoE power levels. It considered a number of important factors including bundle size, cable Assured Assured 0m <= Bundled cabling length <= 50m 2.5GBASE-T 5GBASE-T Assured Assured Assured Category 5e Category 6 Category 6A 50m <= Bundled cabling length <= 75m 2.5GBASE-T 5GBASE-T Assured Category 5e High Medium Low Category 6 Category 6A 75m <= Bundled cabling length <= 100m 2.5GBASE-T 5GBASE-T Assured Assured Assured Category 5e Category 6 Category 6A ALSNR Risk TABLE 2: 2.5 and 5GBASE—T (NBASE-T). ALSNR = Alien Limited Signal to Noise Ratio temperature rating, cable gauge size, and installation environment (e.g., open air, cable tray, conduit) to determine how much power a cable could handle before the heat rise caused the cable to exceed its temperature rating. Most category cables, whether riser or plenum, have a 60°C temperature rating. The study found that many different off-the-shelf cable types and installation methods, especially when dense bundling occurs, experienced a heat rise of more than 15°C. When added to the ambient temperature the cables are tested at, this can cause the cable to exceed its specified temperature rating. Logically, it would seem to make sense that the growth of wireless transmission would result in decreased cable use. But in fact, the category cable market is growing.