Q: Should fiber-optic horizontal cable be installed in innerduct? In the environment in question, plenum fiber-optic cable is being installed between a data closet and a classroom. As you know, educational facilities want quality jobs but are mindful of the costs.
Some of my colleagues favor installing innerduct in the route to protect the fiber and for ease of placement. They cite BICSI`s (Tampa, FL) Cabling Install-ation Manual. Others argue that a fiber-optic cable properly routed through a ceiling cable-support system is as secure as the innerduct system.
But the added expense of a double plenum hit--plenum innerduct and plenum fiber--is not justified because this job is not a multi-tenant environment, in which each customer uses a different vendor and installs different cables. An outside opinion would be refreshing.
LaDonna Hagler
Southwestern Bell
Dallas, TX
A: I believe that prudent use of short pieces of plenum optical-fiber raceway in ducts, plenums, or other spaces used for environmental air is good cable- management design. However, providing a listed plenum optical-fiber raceway from the telecommunications closet to the work-area outlet will continue to make fiber-to-the-desk unnecessarily cost-prohibitive. At 160-pounds force (lbf) pulling tension, optical-fiber cable has always been a more robust medium than the more widely deployed unshielded twisted-pair cable, at 25-lbf pulling tension.
Although BICSI`s Cabling Installation Manual is a good place to start, it is not an industry standard. It did not go through the same industry-wide balloting and comment resolution process that the standards of the Telecommunications Industry Association and Electronic Industries Association (tia/eia--Arlington, VA) are held to. Any comments or questions regarding this manual or other BICSI manuals should be directed to John Siemon of The Siemon Co., chair of the BICSI Engineering and Methods Committee, at John_Siemon@siemon.com.
Donna Ballast is a communications analyst at The University of Texas at Austin and a BISCI registered communications distribution designer (RCDD). Questions can be sent to her at:
Cabling Installation & Maintenance or at PO Drawer 7580,
The University of Texas,
Austin, TX 78713;
tel: (512) 471-0112,
fax: (512) 471-8883,
e-mail: ballast@utexas.edu.
