A type of wiring used in communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility.
There are two types of twisted pair cables:
- shielded twisted pair (STP) cables, in which an additional layer of foil or wire braid is woven around the twisted pairs; and
- unshielded twisted pair (UTP) cables, in which there is a lack of foil or wire braid but costs are lower.
The most commonly-used type of cable, RJ45, uses unshielded twisted pair cables. Ethernet is a protocol that is built on RJ45 cables.
Categories
There are several categories that cables, particularly UTP cables, are classified under:
| Category | Bandwidth | Comments |
|---|---|---|
| Cat 1 | - | Often used in telephony; able to carry voice, but not data. Usually uses RJ11 connectors |
| Cat 2 | 4 Mbps | Obsolete |
| Cat 3 | 10 Mbps | Obsolete |
| Cat 4 | 20 Mbps | Obsolete |
| Cat 5 | 100 Mbps | Almost obsolete |
| Cat 5e | 1 Gbps | An improvement over Cat 5 |
| Cat 6 | 10 Gbps | Cables with this category are limited to 55 metres |
| Cat 6A | 10 Gbps | An augmented version of Cat 6. Cables with this category are limited to 100 metres |