While the Telecommunications Industry Association (TIA-Arlington, VA) wrangles with final specifications for a Category 6 cabling-system standard, another Category 6 standard is already complete. In fact, it's already being revised.
The National Electrical Manufac-turers Association (NEMA-Rosslyn, VA) released the first North American standard for Category 6 and Category 7 telecommunication cables last year. The standard has been labeled: NEMA WC 66-1999, Performance Standard for Category 6 and Category 7 100-Ohm Shielded and Unshielded Twisted Pair Cables.
WC 66 was developed with the purpose of outlining the electrical requirements for premises wiring cables, including minimum electrical performance, allowable conductor sizes, stranding, and shielding. Specifically, cables may be used for voice, data, and video applications requiring bandwidths of up to 200 MHz for Category 6 cable and up to 600 MHz for Category 7 cable. The NEMA standard specifies performance of a cable only; TIA standards specify cabling-system performance.
Developed by NEMA's premises wiring subcommittee, the standard was spawned from industry trends and general industry comments. Work on the standard began in 1994 after the U.S. Department of Defense (DOD) informed NEMA that Category 5 failed to meet the DOD's requirements for classified communication.
In 1997, NEMA learned that the International Organization for Standardization/International Electro- technical Commission (ISO/ IEC-Geneva) had incorporated Category 6 and Category 7 requirements into its latest draft of the ISO/IEC 11801 standard. NEMA responded by addressing these same categories in the WC 66 standard.
As it was working on the first U.S. standard to address these categories, NEMA closely mimicked the actions of the ISO/IEC. On numerous occasions, letter ballots were withdrawn upon discovering that NEMA requirements were "dated" compared to those in ISO/IEC 11801.
"Requirements were constantly being changed, modified, and up-dated," notes Dan Strachan, program manager for NEMA. "The NEMA premises wiring subcommittee took its cues in the development of WC 66 from the changes being made in ISO/IEC 11801."
Numerous cable manufacturers participated in the development of the WC 66 standard. Anixter Inc. (Skokie, IL) has already included WC 66 as a base standard for its Level 7 cable-purchasing specification. NEMA states that work has already begun on the first revision to the standard.
Strachan observes that NEMA expects the standard to be broadly referenced and adopted by other standards organizations.
-Michelle Abrams
