Glossary of Cabling Terms

Cable

A continuous piece of balanced transmission media.

Cabling

A complete system of data delivery, including cables, jumpers , cords, and connecting hardware.

Category rating system

A rating system for the data-handling capacity of cables, connectors, work area cords, and jumpers. Category 1 is the poorest and 7 is the best.

Category 1, 2, and DIW

These cables are not sanctioned by international building-cabling standards.

DIW is the classic 24-AWG twisted-pair phone wire traditionally installed in North America prior to the 1988 specification of category 3 cable. It was the original basis for the category 3 specifications. It should, in theory, meet category 3 specifications, but there are no guarantees . If you are not sure, have each link professionally tested for compliance with category 3.

Category 3

Category 3 cabling, while no longer widely available in the market, remains in many buildings . Category 5e performs better and costs no more.

TIA/EIA 568-B.2-2001 category 3 cable has a plastic (usually PVC) insulation surrounding four distinct pairs of wires. The wires in each pair twist gently around each other, reducing crosstalk between pairs. [62] The performance of this cable is specified to 16 MHz. Also listed in IEC 61156-2 (2001-09).

Category 4

This cable is no longer sanctioned by international building-cabling standards.

At one time the French cable industry manufactured UTP cabling with a nominal characteristic impedance of 120 W . This cable interested only a relatively small community of users in France. Technically, it had somewhat lower attenuation than 100- W cable. Politically, it was hoped that the standardization of this cable as ISO/IEC 11801 category 4 would open new markets for the French cable industry. As it turns out, the U.S. standard TIA/EIA-568 never adopted category 4. It was retracted in ISO/IEC 11801-2002 in favor of category 5e and higher categories, all operating at 100 W .

Category 5

This cable is no longer sanctioned by international building-cabling standards.

EIA/TIA 568-A-1995 category 5 specifies a four-pair balanced cable with performance to 100 MHz. Compared to category 3, the attenuation is much improved by using better dielectric materials, and the crosstalk and noise immunity is much improved by specifying tighter twists . Category 5 cabling has been superceded by Category 5e.

Category 5e

TIA/EIA 568-B.2-2001 category 5e supercedes the older category 5. It has the same general signal attenuation performance as category 5, but includes additional specifications for far-end crosstalk (ELFEXT) and a restating and improvement of the specification for characteristic impedance in the form of return loss. Also listed in IEC 61156-5 (2002-03).

Category 6

TIA/EIA 568-B.2-1-2002 category 6 improves marginally the attenuation requirements of category 5, improves substantially the noise characteristics, and raises the limit of specified performance to 250 MHz. Also listed in IEC 61156-5 (2002-03).

Category 7

IEC 61156-5 (2002-03) category 7 improves marginally the attenuation requirements of category 6, improves substantially the noise characteristics, and raises the limit of specified performance yet again to 600 MHz.

Class C, D, E, and F

ISO/IEC 11801-2002 specifies six classes of balanced cabling performance. Cabling classes C, D, and E are based on cable standards corresponding to TIA/EIA 568-B categories 3, 5e, and 6 respectively. Cabling class F is based on category 7 cables specified in IEC 61156-5.

Number of pairs

TIA/EIA standards stipulate four pairs at each work area outlet. ISO/IEC standards let users squeak by with just two. Four is better, because it leaves the user more options. In addition, the use of all four pairs avoids the problem of having to select which two pairs to equip at each four-pair wall outlet (Ethernet, FDDI, and Token Ring all use different combinations of two pairs). Lastly, new services like Gigabit Ethernet require all four pairs.

UTP

TIA/EIA name for 100- W balanced cables of categories 3, 5e, or 6 with no overall screen. This is the normal form of cabling used in North America.

ScTP

TIA/EIA name for 100- W balanced cables of categories 3, 5e, or 6 with an overall screen.

S/UTP, F/UTP, SF/UTP, S/FTP, F/FTP, SF/FTP

ISO/IEC nomenclature for various forms of shielded twisted-pair cables.

The first part of the name (S, F, or SF) refers to the form of overall screen covering the entire cable. S = braid screen, F = foil screen, or SF = both. No marking indicates no overall screen.

After the slash, the second part of the name (UTP or FTP) refers to the form of element screen used for each balanced element (a pair or a quad). UTP=unscreened, or FTP = foil screened.

150- W STP-A

IBM designed this cable in the early 1980s. Physically, the cable is massive, unwieldy, expensive, and difficult to terminate. Electrically, it is a very fine transmission medium.

Some LAN architectures were first made available on 150- W STP-A because it's easy to get a transceiver up and running on this incredible cable. Mainstream LAN technology, however, uses 100- W balanced cabling.

Although 150- W STP-A is still recognized it is no longer widely available in the market, and may be dropped from future versions of the generic wiring standards.