Q: TIA 568SC specifies connector and adapter colors as beige = multimode and blue = singlemode. But cables going in and coming out of a line interface unit (liu) adapter are specified as orange = multimode and yellow = singlemode. Why the conversion? This creates unnecessary confusion, especially for composite cables terminated in the same liu.
Todd Taylor, RCDD
University of Rochester Medical Center
Rochester, NY
A: To be compliant with TIA/EIA-568a, both the 62.5-micron multimode and the singlemode 568SC connector and adapter have exactly the same dimensions. Hence, they are intermateable. To prevent accidental intermat- ings, tia/eia-568a mandates that the 62.5-micron multimode connector and adapter be beige and the singlemode connector and adapter be blue.
Did you ever wonder why the TR-41.8.1 Fiber Optic Task Group chose beige and blue? I am not certain why blue was chosen for singlemode, but multimode--which at that time was thought to be the only likely candidate for fiber-to-the-desk--was designated as beige to appease the interior decorators.
The 568SC is used not only in the TC but also in the work area, and interior decorators would not like bright orange and yellow cabling draped from the wall outlet to the workstation; the beige adapter and work-area cord were considered less obtrusive. But since tia/eia-568a addressed only patch cords, not work-area cords, no requirement was made as to the color of these cords. Instead, each clause of Section 12 that addresses physical cable specifications says, "The mechanical and environmental specifications for indoor optical-fiber cable shall be in accordance with ansi/ icea S-83-596." ansi/icea S-83-596-1994, Clause 5.9, states, "Unless otherwise specified and at the option of the manufacturer, the jacket may be trans- lucent; if a translucent jacket is not used, the color used for jackets on fiber-optic cable shall be as agreed upon between the manufacturer and user. For fiber-optic cables installed in visible locations, the recommended colors are in Table 5-4." The colors listed in Table 5-4 are sand beige, light beige, olive gray, ivory, white, blue, orange, yellow, black, and dark gray.
My take on this is that the Insulated Cable Engineers Association (icea--South Yarmouth, MA) will allow any color in the rainbow for fiber-optic cable and cord jackets. tia chose beige and blue from the icea`s suggested list. It is not the orange and yellow that most of us have been sold by the manufacturers for so many years, but admittedly is more aesthetically pleasing in the work area.
Donna Ballast is a communications analyst at the University of Texas at Austin and a bicsi reg-istered 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: [email protected].