TIA/EIA-568-B Is Finished!

With the approval of TIA/EIA -568-B.2—Part 2: Balanced Twisted-Pair Cabling Components at the March 2001 meeting of TIA, all three standards making up the TIA/EIA-568-B Commercial Building Telecommunications Cabling Standard are approved and published. Finally, we can retire TIA/EIA-568-A and its five addenda and five associated Technical Service Bulletins (TSBs). But addenda are already in draft form for next-generation multimode fiber systems and for Category 6. This article focuses on the highlights of the copper cabling component standard. TIA/EIA-568-B.2 specifies the requirements for the individual components (cable, connecting hardware, patch cords, and field test equipment) of a balanced twisted-pair cabling system. While this document is primarily intended for manufacturers, users and contractors need to know significant issues associated with the components they will use to build the system. TIA/EIA-568-B.1 is the end-user and contractor document because it establishes system requirements and design criteria, and also field installation and testing requirements. The most significant item is the relegation of Category 5 cable, connecting hardware, and patch cords to a “legacy” status. The only two performance categories recognized and specified are Category 3 and Category 5e. And, because TIA/EIA-568-B.1 recommends Category 5e for the first outlet and requires Category 5e or fiber for the second outlet, it is clear that Category 5 is out and Category 5e and fiber is in. The two significant items in this standard that have not been previously published in any addenda or TSBs are the requirements for Category 5e patch cords and multi-pair backbone cables. Category 5e patch cord requirements address a significant industry and customer need to ensure proper system channel performance. The hopes are that with these specifications and associated test procedures, the industry will achieve interoperability between connecting hardware manufacturers and patch cord manufacturers. But contractors can install the highest-level cabling system using the best cable, connecting hardware, and installation procedures and it will all be for nothing if a poorly performing patch cord is added to the system. Regarding Category 5e multi-pair backbone cables it is my opinion that this is a “day late and dollar short,” given the high-speed backbone market belongs to the fiber industry. Basically, the Category 5e multi-pair backbone cable must meet the same near-end crosstalk (NEXT), equal-level far-end crosstalk (ELFEXT) and propagation delay skew requirements as four-pair Category 5e based on testing as four-pair units but must meet Category 5e requirements on all-pairs combined within a 25-pair group for power-sum requirements, such as power-sum near-end crosstalk (PSNEXT) and power-sum equal-level far-end crosstalk (PSELFEXT). The change from Category 5 to Category 5e and the necessity to address four-pair transmission versus two-pair transmission resulted in a number of significant changes at the component level and with the establishment of qualification test procedures for components. To highlight the significance of the testing issues associated with this move to Category 5e you only have to look at the page count of the TIA/EIA-568-B.2 document. The standard for copper components is 150 pages long, the same size as TIA/EIA-568-A that not only included copper but also fiber and the system requirements. Of the 150 pages, only 30 actually deal with the specifications of the recognized components; however, 42 pages are needed to establish the test procedures for manufacturers and 22 pages are needed to establish the requirements for Category 5e (Level IIe) field test equipment. The remaining pages cover additional items such as table of contents, scope, other copper cabling components and such. A significant testing and qualification change is the replacing of the previously used Terminated Open Circuit (TOC) test method with the “de-embedded” test method. With the need for the components and systems to support higher data rates and four-pair transmissions, it has been determined that TOC was not adequate to test all the necessary parameters and needed also to consider both magnitude and phase of performance. Specific de-embedded NEXT values, both magnitude and phase for all six-pair combinations, have been established for the test plug to be used in qualifying connecting hardware. The de-embedding procedure has the objective of yielding a mated (jack-to-plug) NEXT loss accuracy of ± 1 dB. Additionally, a very elaborate test head, which has to be qualified to a wide range of de-embedded plugs, has been specified for patch cord qualification. Also significantly changed were the requirements for a Level IIe tester. Addendum 5 to TIA/EIA-568-A specified Level IIe field testers out to 100MHz. Now with the 568-B.2 Level IIe testers, performance and accuracy is not only specified for 100MHz, but also for 250MHz. This is in anticipation of the future addendum for Category 6 cabling systems, even though performance parameters of the system, or the components, are still in ballot. So, while the trinity of “system, copper, and fiber” is complete for TIA/EIA-568-B, additions are already underway. BEAM is director of systems marketing at AMP NETCONNECT Systems. He can be reached at (336) 727-5784 or tebeam@tycoelectonics.com.

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