CATEGORY 5 CABLE

(Redirected from Category 5e)

'Category 5 cable', commonly known as 'Cat 5', is a twisted pair cable type designed for high signal integrity. Many such cables are unshielded but some are shielded. Category 5 has been superseded by the 'Category 5e' specification. This type of cable is often used in structured cabling for computer networks such as Ethernet, and is also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances).

Contents
Usage and wiring methods
Category 5
Category 5e
Connectors and other information
See also
External links

Usage and wiring methods



8P8C modular plug pin positioning


TIA/EIA-568-B T568A Wiring
Pin Pair Wire Color
1 3 1
Pair 3 Wire 1
white/green
2 3 2
Pair 3 Wire 2
green
3 2 1
Pair 2 Wire 1
white/orange
4 1 2
Pair 1 Wire 2
blue
5 1 1
Pair 1 Wire 1
white/blue
6 2 2
Pair 2 Wire 2
orange
7 4 1
Pair 4 Wire 1
white/brown
8 4 2
Pair 4 Wire 2
brown


TIA/EIA-568-B T568B Wiring
Pin Pair Wire Color
1 2 1
Pair 2 Wire 1
white/orange
2 2 2
Pair 2 Wire 2
orange
3 3 1
Pair 3 Wire 1
white/green
4 1 2
Pair 1 Wire 2
blue
5 1 1
Pair 1 Wire 1
white/blue
6 3 2
Pair 3 Wire 2
green
7 4 1
Pair 4 Wire 1
white/brown
8 4 2
Pair 4 Wire 2
brown


Image of partially stripped cable showing the twisted pairs.


Image of a Cat 5E Wall outlet showing the two wiring schemes: A for T568A, B for T568B.


Category 5

The original specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specified performance characteristics and test requirements for frequencies of up to 100 MHz.
Category 5 cable includes four twisted pairs in a single cable jacket. This use of balanced lines helps preserve a high signal-to-noise ratio despite interference from both external sources and other pairs (this latter form of interference is called crosstalk). It is most commonly used for 100 Mbit/s networks, such as 100BASE-TX Ethernet, although IEEE 802.3ab defines standards for 1000BASE-T - Gigabit Ethernet over category 5 cable. Cat 5 cable typically has three twists per inch of each twisted pair of 24 gauge copper wires within the cable. May be unsuitable for 1000BASE-T gigabit ethernet.
Category 5e

'Cat 5e' cable is an enhanced version of Cat 5 that adds specifications for far end crosstalk. It was formally defined in 2001 in the TIA/EIA-568-B standard, which no longer recognizes the original Cat 5 specification. Although 1000BASE-T was designed for use with Cat 5 cable, the tighter specifications associated with Cat 5e cable and connectors make it an excellent choice for use with 1000BASE-T. Despite the stricter performance specifications, Cat 5e cable does not enable longer cable distances for Ethernet networks: cables are still limited to a maximum of 328 ft (100 m) in length (normal practice is to limit fixed ("horizontal") cables to 90 m to allow for up to 5 m of patch cable at each end). Cat 5e cable performance characteristics and test methods are defined in TIA/EIA-568-B.2-2001.
Connectors and other information

The cable exists in both stranded and solid conductor forms. The stranded form is more flexible and withstands more bending without breaking and is suited for reliable connections with insulation piercing connectors, but makes unreliable connections in insulation displacement connectors. The solid form is less expensive and makes reliable connections into insulation displacement connectors, but makes unreliable connections in insulation piercing connectors. Taking these things into account, building wiring (for example, the wiring inside the wall that connects a wall socket to a central patch panel) is solid core, while patch cables (for example, the movable cable that plugs into the wall socket on one end and a computer on the other) are stranded.
Cable types, connector types and cabling topologies are defined by TIA/EIA-568-B. Nearly always, 8P8C modular connectors, often incorrectly referred to as "RJ-45", are used for connecting category 5 cable.
The cable is terminated in either the T568A scheme or the T568B scheme. It doesn't make any difference which is used, as they are both straight through (pin 1 to 1, pin 2 to 2, etc), as long as one standard is used consistently. The article Ethernet over twisted pair describes how the cable is used for Ethernet, including special "cross over" cables.
Mixed cable types should not be connected in serial, as the impedance per pair differs and would cause signal degradation.

See also



Category 6 cable

External links



Cable your own house - written in 1999 and does have some out-of-date information.

Wiring up Cat 5

Ethernet pinout guide

Structured cabling instructions

How to wire your own Ethernet cables

Wiring telephones over structured cabling

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