Stranded vs. solid Category 5 cable

Q: My company has been asked to bid on a high school project in Simi Valley, CA, where the school already has Category 5 cable pulled above the dropped ceilings, but nothing has been terminated yet. This was done as part of the NetDay `96 project. Unfortunately, the installers were supplied patch-cord stranded cable, not solid wire--16,000 feet of it pulled into five buildings. All cable runs are indoors--between 30 feet and 150 feet maximum--and the cable is Helix/Hi-Temp, 4-pair. As a certifi

Q: My company has been asked to bid on a high school project in Simi Valley, CA, where the school already has Category 5 cable pulled above the dropped ceilings, but nothing has been terminated yet. This was done as part of the NetDay `96 project. Unfortunately, the installers were supplied patch-cord stranded cable, not solid wire--16,000 feet of it pulled into five buildings. All cable runs are indoors--between 30 feet and 150 feet maximum--and the cable is Helix/Hi-Temp, 4-pair. As a certified installer, I am reluctant to bite off more than I can chew, but I want to help.

I assume that you would advise to proceed on the installation as is--not start all over--and to replace only the cable that fails. Can I expect any surprises during the installation and testing caused by the use of stranded cable? What should I look for when testing the installation: high attenuation, marginal near-end crosstalk? How do I distinguish between normal installer-type problems and stranded-cable issues?

Dave Chaney, President

C&W Fiber Optics Inc.

Moorpark, CA

A: Yes, your client is in for a surprise, but we may be able to salvage part of the job. However, do not guarantee anything. Some customers tend to blame the last guy who touched the installation.

Regarding your question on testing: Yes, look for high attenuation. Stranded cable has more than 20% attenuation over solid. On runs of the lengths you mention, however, the installation should still pass Category 5 tests.

The "fun" part of this installation is that you will need connecting hardware that can terminate stranded cable. The Siemon Co. (Watertown, CT) manufactures 110 blocks that are rated for stranded and solid cable, but I do not know about outlet/connectors. If you already have, or are planning to use, other connecting hardware, check with the manufacturer.

As for distinguishing between installer problems and stranded-cable issues, if your tests show opens, shorts, crosses, pair reversals, and near-end crosstalk (caused by untwisting the pairs more than 0.5 inch), these would most likely be caused by incorrect installation. Anything else could be caused by the cable or a combination of the stranded cable on incompatible connecting hardware.

Donna Ballast is a communications analyst at the University of Texas at Austin and a bicsi registered communications distribution designer (rcdd). Questions can be sent to her at Cabling Installation & Maintenance or at PO Drawer 7580, University of Texas, Austin, TX 78713; tel: (512) 471-0112, fax: (512) 471-8883, e-mail: ballast@utexas.edu.

More in Cabling Installation