More on Protecting Exposed Fibers . . .

Oct. 1, 1996
Paul Kolesar, Lucent Technologies (Middletown, NJ), offers the following comment regarding my response to the question about exposed buffered fibers in the classroom installation (see August 1996).

Paul Kolesar, Lucent Technologies (Middletown, NJ), offers the following comment regarding my response to the question about exposed buffered fibers in the classroom installation (see August 1996).

The fiber installation described brings the horizontal cabling directly to electronics and exposes the buffered fibers in the classroom, violating not only the intent, but also the letter of the Tia/eia-568a standard.

You point out that Section 12.4.5 explicitly requires a telecommunications outlet for dark fibers. This is to keep the dark fiber ends from being left inside the walls, or unprotected after being pulled. Without a telecommunications outlet to hold the ends, the dark fibers could easily be misplaced, forgotten or damaged.

The broader issue, however, is the interpretation of what is permitted with the active fibers. Section 12.4.5 does not explicitly require an outlet for the active fibers simply because this is an issue relating to all media, not only to fiber. That is why the requirement for telecommunications outlets is covered in Section 4 on horizontal cabling. Several references can be found that discuss the use of outlets at the work area, including Sections 4.1, 4.2 and 4.5. However, these sections may not define sufficiently what is meant by an optical telecommunications outlet/connector, nor require the use of a faceplate to house it at the work area.

Fortunately for fiber installations, one of the loopholes is closed in Section 12.7 on cabling practices. This section requires adapters at both ends of optical-fiber links and also fills the void in the definition of the telecommunications outlet/connector for optical fiber: The outlet/connector for fiber is the adapter. Based on this last reference alone, the installation at the school in Oregon does not comply with the Tia/eia-568a standard.

Paul Kolesar

Lucent Technologies

Middletown, NJ

While discussing our differences of opinion, Kolesar explained the intent of Section 12.4.5; however, I believe that we do not pay contractors for intent--we pay them for compliance, regardless of intent.

In the third paragraph of Section 12.7.1, Polarization, the Tia/eia-568a standard states: "The crossover shall be achieved by using consecutive fiber numbering (that is, 1, 2, 3, 4. . .) on both ends of an optical-fiber link, but the 568SC adapters shall be installed in opposite manners on each end (that is, A-B, A-B. . . on one end and B-A, B-A. . . on the other). This approach is illustrated in Figure 12-6," which shows a 6-fiber patch cable installed between two fiber patch panels.

Before publication of the August column, I discussed my answer with several members of the Fiber Optic Task Group, requesting them to use the words in the Tia/eia-568a published standard to disprove my answer. We also discussed "intent." If it is the intent that a telecommunications outlet/connector box and an adapter mounted in a faceplate be installed, then it should be spelled out.

If the current version of the standard being referenced does not state exactly what is required, detail it on the drawings and specifications. Relying on a sentence that discusses adapter orientation to get an optical-fiber outlet box in the wall, a faceplate and a properly polarized adapter may get you an installation similar to the one in the Oregon school.

A word of caution: Do not make the statement "Shall comply with TIA-..." if you do not know exactly what the standard requires. For example, I received a call from a management information system manager for a state agency who asked me to fax her the section of the Tia/eia-606 standard that covers labeling of the cables at the horizontal crossconnect. She wanted to prove a point to her contractor. After asking for a more specific description of the problem, I learned that the contractor had labeled each termination, and the numbers were the same as those on the outlet/connector end--but they were in random order on the horizontal crossconnect (56, 78, 1, 19. . .). In fact, the Tia/eia-606 standard does not address the order of termination. That makes it a design issue.

Donna Ballast

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