![CAT5e Cable](https://upload.wikimedia.org/wikipedia/commons/d/d1/CAT5e_Cable.jpg)
Category 5 cable (Cat 5) is a
twisted pair
Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted ba ...
cable for
computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
s. Since 2001, the variant commonly in use is the Category 5e specification (Cat 5e). The cable standard provides performance of up to 100 MHz and is suitable for most varieties of
Ethernet over twisted pair
Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. They are a subset of all Ethernet physical layers.
Early Ethernet used various grades of coaxial cable, but in 1984, Sta ...
up to
2.5GBASE-T but more commonly runs at (Gigabit Ethernet) speeds. Cat 5 is also used to carry other signals such as
telephone
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into e ...
and
video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syst ...
.
This cable is commonly connected using
punch-down block
A punch-down block (also punchdown block, punch block, punchblock, quick-connect block and other variations) is a type of electrical connection often used in telephony. It is named because the solid copper wires are "punched down" into short open ...
s and
modular connector
A modular connector is a type of electrical connector for cords and cables of electronic devices and appliances, such as in computer networking, telecommunication equipment, and audio headsets.
Modular connectors were originally developed fo ...
s. Most Category 5 cables are
unshielded, relying on the
balanced line twisted pair design and
differential signaling
Differential signalling is a method for electrically transmitting information using two complementary signals. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conduc ...
for noise rejection.
Standards
The specification for category 5
cable
Cable may refer to:
Mechanical
* Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof
* Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...
is defined in
ISO/IEC 11801
International standard ISO/IEC 11801 ''Information technology — Generic cabling for customer premises'' specifies general-purpose telecommunication cabling systems (structured cabling) that are suitable for a wide range of applications (analog an ...
,
IEC 61156 and
EN 50173.
The specification for category 5 cable was defined in
ANSI
The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...
/
TIA/EIA-568-A, with clarification in TSB-95. These documents specify performance characteristics and test requirements for
frequencies up to 100 MHz.
The cable is available in both stranded and solid conductor forms. The stranded form is more flexible and withstands more bending without breaking.
Patch cables are stranded. Permanent wiring used in
structured cabling is solid-core. The category and type of cable can be identified by the printing on the jacket.
The category 5 specification requires conductors to be pure copper. The industry has seen a rise in non-compliant / counterfeit cables, especially of the Copper Clad Aluminum (CCA) variety. This has exposed the manufacturers or installers of such fake cable to legal liabilities.
Variants and comparisons
The category 5e specification improves upon the category 5 specification by revising and introducing new specifications to further mitigate the amount of
crosstalk. The
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
(100 MHz) and physical construction are the same between the two, and most Cat 5 cables actually meet Cat 5e specifications, though they are not specifically certified as such. The category 5 was deprecated in 2001 and superseded by the category 5e specification.
The
Category 6 specification improves upon the Category 5e specification by extending frequency response and further reducing crosstalk. The improved performance of Cat 6 provides 250 MHz bandwidth.
Category 6A cable provides 500 MHz bandwidth. Both variants are
backward compatible
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially in ...
with Category 5 and 5e cables.
Termination
Cable types, connector types and cabling topologies are defined by
ANSI/TIA-568
ANSI/TIA-568 is a technical standard for commercial building cabling for telecommunications products and services. The title of the standard is ''Commercial Building Telecommunications Cabling Standard'' and is published by the Telecommunication ...
. Nearly always,
8P8C modular connector
A modular connector is a type of electrical connector for cords and cables of electronic devices and appliances, such as in computer networking, telecommunication equipment, and audio headsets.
Modular connectors were originally developed for ...
s (often referred to incorrectly as
RJ45 connectors) are used for connecting category 5 cable. The cable is terminated in either the
T568A scheme or the
T568B
ANSI/TIA-568 is a technical standard for commercial building cabling for telecommunications products and services. The title of the standard is ''Commercial Building Telecommunications Cabling Standard'' and is published by the Telecommunications ...
scheme. The two schemes work equally well and may be mixed in an installation so long as the same scheme is used on both ends of each cable.
Applications
Category 5 cable is used in structured cabling for
computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
s such as
Ethernet over twisted pair
Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. They are a subset of all Ethernet physical layers.
Early Ethernet used various grades of coaxial cable, but in 1984, Sta ...
. The cable standard prescribes performance parameters for frequencies up to and is suitable for , (Fast Ethernet), (Gigabit Ethernet), . and Ethernet connections require two wire pairs. 1000BASE-T and faster Ethernet connections require four wire pairs. Through the use of
power over Ethernet
Power over Ethernet, or PoE, describes any of several Technical standard, standards or ad hoc systems that pass electric power along with data on Ethernet over twisted pair, twisted-pair Ethernet cabling. This allows a single cable to provide ...
(PoE),
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
can be carried over the cable in addition to Ethernet data.
Cat 5 is also used to carry other signals such as
telephony
Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...
and
video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syst ...
. In some cases, multiple signals can be carried on a single cable; Cat 5 can carry two conventional telephone lines as well as 100BASE-TX in a single cable. The
USOC/RJ-61 wiring standard may be used in multi-line telephone connections. Various schemes exist for transporting both analog and digital video over the cable.
HDBaseT is one such scheme.
Characteristics
The use of
balanced lines helps preserve a high
signal-to-noise ratio despite interference from both external sources and crosstalk from other pairs.
Insulation
Outer insulation is typically
polyvinyl chloride (PVC) or
low smoke zero halogen (LS0H).
Bending radius
Most Category 5 cables can be bent at any radius exceeding approximately four times the outside diameter of the cable.
Maximum cable segment length
The maximum length for a cable segment is per TIA/EIA 568-5-A. If longer runs are required, the use of active hardware such as a repeater or switch is necessary. The specifications for 10BASE-T networking specify a 100-meter length between active devices. This allows for 90 meters of solid-core permanent wiring, two connectors and two stranded patch cables of 5 meters, one at each end.
Conductors
Since 1995, solid-conductor UTP cables for backbone cabling is required to be no thicker than 22
American Wire Gauge (AWG) and no thinner than 24 AWG, or 26 AWG for shorter-distance cabling. This standard has been retained with the 2009 revision of ANSI TIA/EIA 568.
Although cable assemblies containing are common, category 5 is not limited to 4 pairs. Backbone applications involve using up to .
Individual twist lengths
The distance per twist is commonly referred to as pitch. Each of the four pairs in a Cat 5 cable has differing precise pitch to minimize
crosstalk between the pairs. The pitch of the twisted pairs is not specified in the standard. Measurements on one sample of Cat 5 cable yielded the following results.
Since the pitch of the various colors is not specified in the standard, pitch can vary and should be measured for the batch being used if the cable is being used in a non-Ethernet situation where pitch may be critical.
Environmental ratings
Some cables are "UV-rated" or "UV-stable" meaning they can be exposed to outdoor
UV radiation without significant degradation.
Plenum-rated cables are slower to burn and produce less smoke than cables using a mantle of materials like PVC. Plenum-rated cables may be installed in
plenum space
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure. Space ...
s where PVC is not allowed.
Shielded cables (
FTP or STP) are useful for environments where proximity to
RF equipment may introduce
electromagnetic interference, and can also be used where
eavesdropping
Eavesdropping is the act of secretly or stealthily listening to the private conversation or communications of others without their consent in order to gather information.
Etymology
The verb ''eavesdrop'' is a back-formation from the noun ''eaves ...
likelihood should be minimized.
References
Further reading
*
{{DEFAULTSORT:Category 5 Cable
Ethernet cables
Transmission lines