Category 3 cable (Cat3)

Category 3 cable, commonly known as Cat 3, is an unshielded twisted pair (UTP) cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz.

Category 3 was a popular cabling format among computer network administrators in the early 1990s, but fell out of popularity in favor of the very similar, but higher performing, Category 5 cable standard. Since the early 2000s most new structured cable installations are built with Cat 5e or Cat 6 cable.

Cat 3 is currently still in use in two-line telephone systems. It may be used for 10BASE-T Ethernet, token ring, or ATM25 networks. The seldom used 100BASE-T4 standard, which achieves speeds of 100 Mbit/s by using all 4 pairs of wires, allowed older Cat 3 based infrastructures to achieve a much higher bandwidth. Cat 3 is compatible with Power over Ethernet.

Note that unlike Cat 1, 2, 4, and 5 cables, Cat 3 is still recognized by TIA/EIA-568-B, its defining standard.

Category 5 cable (Cat 5e)

This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video.Most Category 5 cables are unshielded, relying on the twisted pair design and differential signaling for noise rejection. Category 5 has been superseded by the Category 5e specification.

Conductors required

10BASE-T and 100BASE-TX Ethernet connections require two cable pairs. 1000BASE-T Ethernet connections require four cable pairs.

Bending radius

Most Cat 5 cables can be bent at a radius approximately 4 times the diameter of the cable.

Maximum cable segment length

According to the ANSI/TIA/EIA standard for category 5e cable, (TIA/EIA 568-5-A) the maximum length for a cable segment is 100 meters. If longer runs are required, the use of active hardware such as a repeater, or a switch, is necessary. The specifications for 10BASE-T networking specify a 100 metre length between active devices. This allows for 90 metres of fixed cabling, two connectors and two patch leads of 5 metres, one at each end.

Category 6 cable (Cat6)

Cat 6, is a cable standard for Gigabit Ethernet and other network Physical Layers that is backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat 5 and Cat 5e, Cat 6 features more stringent specifications for crosstalk and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T/1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet).

Whereas Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a cable, is characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols.