A twisted pair cable consists of four twisted pairs of wires - 8 wires in total. The copper wires used in the cable can either be solid or stranded. Cables using solid wires are mainly made for stationary use. Stranded wires have a higher tolerance for bending which makes them good for patch cables. The twisting of the cable pair lessens electromagnetic interference which could come from power cables in the proximity. When added a foil shield, it also significantly reduces crosstalk between the neighboring cable pairs.
The outer shell is usually made of PVC. The cables usually have a halogen-free exterior in order to prevent the release of dangerous gas or acidic compounds in case of a fire. (abbreviation: LSZH or LS0H).
The labeling of the shielding is standardized with ISO / IEC-11801. The structure of the labeling is: XX/YZZ .
XX - exterior shielding
U: unshielded
F: foil
S: braided shield
SF: foil + braided shield
Y - twister pair shielding
U: unshielded
F: foil
S: braided shield
ZZ
always stands for
TP: twisted pair
Twisted pair cable categories
Twisted pair cables have been standardized and divided into the following categories. Each category includes different characteristics and requirements. Current categories 5 to 8 have been specified in the standard ISO / IEC 11801.
Additionally, and European standard EN 50173 is used, where twisted pair cables are divided into classes from A to I.
