By Barbara E. Thompson
The Building Industry Consulting Service International Inc. conference held in Toronto, June 5 to 8, 1995, included multimedia and networking topics. Approximately 750 attendees went to sessions and workshops that covered such subjects as practical field testing of optical fiber cables, unshielded twisted-pair links, firestopping and the office of the future.
In addition, standards and business meetings were held and 70 exhibitors showcased their products. Of significance to installers, however, were the workshop on UTP link testing and discussions at the standards committee meeting on intermateability problems with racks.
The purpose of the workshop on link testing, coordinated by Masood Shariff and Brian Bancroft, technical staff at AT&T Bell Laboratories (Middletown, NJ), was to establish that Category 5 field testing is standardized with the proposed Electronic Industries Association/Telecommunications Industry Association Technical Systems Bulletin 67. Shariff indicated that TSB-67 is close to agreement and publication, and this workshop was designed to demonstrate the practical aspects of the document for field testing.
Uniform testing approach
The workshop did not compare different field test instruments, "but intended to demonstrate commonality resulting from compliance with TSB-67 requirements," explained Shariff. "The purpose [of the workshop] is to show that standardization has led to a uniform approach to testing of UTP cabling and will lead to relatively consistent results using different instruments."
The workshop consisted of hands-on testing of 4-pair Category 5 unshielded twisted-pair cabling runs followed by interpretation of test results. Technical representatives from six manufacturers of Category 5 testers--Datacom Technologies Inc., Fluke Corp., Microtest Inc., Scope Communications Inc., Wandel & Goltermann Inc. and Wavetek Corp.--were available to help workshop participants use their test instruments.
Attendees had a chance to use all six instruments on a variety of cabling runs, some of which had been intentionally modified to fail. Both basic link and channel configurations were included, and participants were given a printed report for each link tested. Because it is important for installers to be able to interpret their test data, attendees were asked first to use the tester to identify the cabling runs that failed and then visually confirm the type of failure. "Testers do not replace physical examination," says Shariff. "They are only tools to enhance the physical examination."
When questioned during the discussion segment, Shariff supplied a few details about the testers, such as:
Y Testing is done at 20C.
Y Only one parameter can be changed by the operator--nominal velocity of propagation. The operator changes the NVP according to cable specifications.
Y The tester manufacturer states the accuracy of the tester for basic link and channel.
One attendee asked if power-sum near-end crosstalk could be measured by testers. Shariff replied that "there is a laboratory instrument that does this, but no field testers are available yet to measure power sum near-end crosstalk."
BICSI standards meeting
The TSB-67 was also discussed at the BICSI standards meeting. One problem reviewed was the failure of short links (15 meters or less) when using handheld testers on a Category 5 system. The BICSI TR41 representative, Donna Ballast, registered communications distribution designer, informed the standards group that the problem "was not with the cable tester, but was a connecting hardware resonance phenomenon. While not all connecting hardware is affected, some manufacturers have already made design changes," she said.
Another installer issue --and one that brought to the standards meeting representatives from B-Line Systems Inc., Chatsworth Products Inc., Schroff Inc., Steelcase North America and Vero Electronics Inc.--was the subject of intermateability between cabinets and racks from different manufacturers. "Installers feel that when you buy a rack," Ballast explained, "you should be able to use the same size rack from any manufacturer and have the hole configurations match up." The committee assigned a task group to formulate a proposed rack and cabinet standard. We will probably hear more about this at the next BICSI Conference, to be held in Tucson, AZ, September 25 to 28, 1995.
For more information, contact BICSI at (800) 242-7405.