Preferred Cable Combinations

TIA/EIA 568-B.1 and ISO/IEC 11801 do more than simply define acceptable types of horizontal cabling. They define in what combinations such cables should be used. According to the standards, two horizontal links serve each work area .

The work area in Figure 7.3 shows a pair of links in typical usage. One serves the phone and the other serves the data device.

Table 7.2 shows cable combinations permitted by both standards. Here I have listed only the arrangements preferred by TIA/EIA 568-B.1-2001, not all the compliant possibilities.

ISO/IEC specifications are somewhat more permissive than TIA/EIA. Permissive standards proliferate unnecessary cable choices. For example, ISO/IEC permits substitution of category 3, 5e, 6, or 7 cables and substitution of practically any type of optical fiber for the items listed in Table 7.2

Based on my belief that fiber-to-the-desk won't happen any time soon, I tell users to install category 5e four-pair 100- W balanced cabling to both outlets.

Table 7.2. Preferred Horizontal Cable Combinations

TIA/EIA 568-B.1-2001

First outlet:

• Four-pair, 100- W UTP, category 5e or better

Second outlet, any one of

• Four-pair, 100- W UTP, category 5e or better
• Two- strand , 62.5/125 m m fiber
• Two-strand, 50/125 m m fiber