Structured cabling for data and voice communications is the standardized infrastructure (by TIA/EIA and IEEE) for telephone and local area network (LAN). These standards are TIA/EIA 568 and IEEE 802.3. Nowadays structured cabling is also part of the AV world.

This cabling is made up of 4 twisted pairs (shielded or unshielded) with an impedance of 100 Ω. Conductor diameter depends on the category, ranging from 24 to 23 AWG (the higher the category, the larger the diameter).).

Each pair can be differentiated by colour:

Pair 1: White/Blue – Blue

Pair 2: White/Orange – Orange

Pair 3: White/Green – Green

Pair 4: White/Brown – Brown

It can be changed by each manufacturer.

Structured cabling is classified into different categories::

CAT 3: 10 BASET//Bit rate: 10 Mbps//Bandwidth: 16 MHz

CAT. 5: 100 BASET//Bit rate:100 Mbps //Bandwidth: 100 MHz

CAT 5E: 1000 BASET//Bit rate: 1000 Mbps or 1 Gbps//Bandwidth: 100 MHz. (Class D)

CAT. 6: 1000 BASET//Bit rate: 1000 Mbps or 1Gbps//Bandwidth: 250 MHz. (Class E)

CAT 6A: 10GBASE-T//Bit rate: 10 Gbps//Bandwidth: 500 MHz or 625 MHz versions (Clase EA).

Physically, the category can be distinguished by the diameter of the conductors and especially by the twist rate. Higher categories feature more twists.

The naming convention specified by ISO/IEC 11801 is as follows::

XX/ZTP

XX = Overall shielding:

F = foil shielded

S = braid shielded

SF = braid and foil shielded

Z = Individual shield each pair:

U = unshielded

F = foil shielded

TP = Twisted pair.

An F/UTP cable features an overall foil shield and no individual pair shielding.

An FTP cable features a foil shield around each pair.

An SF/UTP cable features double shielding (braid and foil) and no individual pair shielding.

NOTE: Some cables, besides having double shielding, are composed of a double jacket for higher protection against external aggressions (CABLE SF/UTP)

The overall shielding reduces external interference, such as EMI (Electromagnetic interference) or RFI (Radio-frequency interference), and the individual shielding reduces interference between pairs in the same cable (crosstalk).).).

Bibliography: Handbook for Sound Engineers. Fourth Edition. Glen Ballou. Focal Press.