What Is Unshielded-Twisted-Pair (UTP) Cable

  :: What is UTP Cable?

  UTP cable picture

  UTP stands for Unshielded Twisted Pair cable. UTP cable is a 100 ohm copper cable that consists of 2 to 1800 unshielded twisted pairs surrounded by an outer jacket. They have no metallic shield. This makes the cable small in diameter but unprotected against electrical interference. The twist helps to improve its immunity to electrical noise and EMI.

  (You can get Cat 5e and Cat 6 UTP Patch Cable from us)

  For horizontal cables, the number of pairs is typically 4 pair as shown below.

  UTP Cable Picture

  For backbone cables, the number of pairs will typically be some increment of 25, because multi-pair UTP cables are constructed in 25-pair binder group. A sample backbone UTP cable is shown below.

  Backbone UTP cable

  :: UTP Copper Cable Conductor Size

  The copper conductor of both horizontal and backbone UTP cables are either 22 AWG or 24 AWG. 24 AWG is the most common size, but higher-performance cables like Category 6 UTP employ the larger 23 AWG copper wires.

  :: Solid Conductor UTP Cable and Stranded Conductor UTP Cable

  1) Solid Conductor UTP Cable

  solid conductor UTP cable

  Solid Conductor UTP Cable Picture

  As its name implies, solid conductor UTP cables have a single, solid conducting copper wire as the conductor. In addition to being physically stronger and easier to work with, these larger wires have superior electrical characteristics that remain stable over a wider range of frequencies.

  Solid conductor cables have a lower DC resistance and a lower susceptibility to high-frequency effects based on their larger diameters alone. These properties allow solid conductor cables to support longer transmission runs and higher data rates than their stranded cable counterparts.

  UTP cables used for both horizontal and backbone applications are typically solid conductor cables.

  2) Stranded Conductor UTP Cable

  stranded conductor UTP cable

  Stranded Conductor UTP Cable Picture

  Stranded-conductor UTP cables are typically used as patch cables in either work areas or telecommunication rooms. They are the most common Category-type cables we often directly work with.

  Inside the twisted pairs of a stranded cable, each individual conductor is made up of a bundle of smaller-gauge wire strands. These are arranged so that several wires (commonly 6 or 18) surround a single wire at the bundle’s center. The outer wires are wrapped helically around the central wire through a process called stranding. The stranded wires together form a single conductor with an overall diameter about the same as that of a conductor in a solid cable, but with a much smaller conducting area (based on the smaller diameters of the conducting wire strands).

  The stranding of the wire conductors serves to protect them, and gives stranded cables their flexibility.

  :: UTP Cable Applications

  UTP cables are mostly used for LAN networks. They can be used for voice, low-speed data, high-speed data, audio and paging systems, and building automation and control systems. UTP cable can be used in both the horizontal and backbone cabling subsystems.

  :: UTP Cable Categories and Performance Specifications

  UTP cables were invented for voice applications. Voice UTP cables only needed to carry analog signals which are very robust and not easily corrupted by electrical noise or EMI. However, as UTP cables were used for different systems, higher quality UTP cables were required to support data systems that used digital signaling.

  As the applications evolved, different categories or grades of UTP cables were created? along these years. Higher category UTP cables are referred to as data grade UTP cables, and low category UTP cables are referred to as voice grade UTP cables.

  The following table shows different Category UTP cables, their business applications and corresponding performance specification.

  Note:

  TIA/EIA-568 only recognized cables of Category 3 ratings or above. Category 1 cable (Cat 1) and Category 2 (Cat 2) voice-grade coppers are a misnomer, probably adopted by those who assumed that TIA set up “Categories” for all types of cables originally defined by Anixter International, the distributor, under the grades called “Levels.”

  Cat 1 cable is used in earlier times. It is used for typically voice networks that carries only voice traffic example telephones.

  Anixter Level 2 (Cat 2) was a grade of UTP cable capable of transmitting data at up to 4 Mbit/s. It is the first cable which can transmit voice and data up to 4mbps. Anixter Level 2 cable was frequently used on ARCnet and 4 Mbit/s token ring networks, it is also used in telephone networks but it is no longer commonly used.

  Category

  Grade

  Business Application

  Frequency Range

  Category 1

  voice grade

  voice-grade telephone networks only; not for data transmissions

  750 kHz

  Category 2

  voice grade

  voice-grade telephone networks, as well as IBM dumb-terminal connections to mainframe computers

  1 MHz

  Category 3

  data grade

  voice-grade telephone networks, 10Mbps Ethernet, 4Mbps Token Ring, 100BaseT4 Fast Ethernet, and 100VG Any LAN

  16 MHz

  Category 4

  data grade

  16Mbps Token Ring networks

  20 MHz

  Category 5

  data grade

  100BastTX Fast Ethernet, SONET, and OC-3 ATM networks

  100 MHz

  Category 5e

  data grade

  Gigabit (1000Mbps) Ethernet

  100 MHz

  Category 6

  data grade

  Gigabit (1000Mbps) Ethernet

  250 MHz

  Category 6A

  data grade

  Gigabit (1000Mbps) and 10 Gigabit Ethernet

  500 MHz

  :: UTP Cable Color Codes

  1) UTP Horizontal Cable Color Code

  Horizontal UTP cable is four-pair construction by industry cabling standard. Each pair has two conductors. One wire of the pair is assigned the pair color with a white stripe and the other wire is assigned the color white with the pair color stripe. The table below lists the pair and color code for a four-pair horizontal UTP cable.

  Wire Number

  Pair Number

  Color

  1

  1

  60px-Wire_white_blue_stripe.svg white/blue

  2

  1

  60px-Wire_blue.svg blue

  3

  2

  60px-Wire_white_orange_stripe.svg white/orange

  4

  2

  60px-Wire_orange.svg orange

  5

  3

  60px-Wire_white_green_stripe.svg white/green

  6

  3

  60px-Wire_green.svg green

  7

  4

  60px-Wire_white_brown_stripe.svg white/brown

  8

  4

  60px-Wire_brown.svg brown

  ?

  2) UTP Backbone Cable Color Code

  UTP backbone cables are large, multi-pair cables. These cables are constructed of 25-pair binder groups. Each binder group is individually color coded and each pair within a 25-pair binder group is individually color coded.

  ?

  (a) 25-pair Binder Group Color Code

  The 25-pair binder group is organized into five groups and there are five pairs in each group. The five color groups in a 25-pair binder are

  White – pairs 1 to 5

  Red – pairs 6 to 10

  Black – pairs 11 to 15

  Yellow – pairs 16 to 20

  Violet – pairs 21 to 25

  Within each color group, the five pairs are designated with the group color code and the pair color code. The pair color code for each of the five pairs with a color coded group are

  Blue – 1st pair of the color code group

  Orange – 2nd pair of the color code group

  Green – 3rd pair of the color code group

  Brown – 4th pair of the color code group

  Slate – 5th pair of the color code group

  The color code for a 25-pair binder group is shown in the following table.

  Wire Number

  Pair Number

  Group Color Code

  Pair Color Code

  Color

  1

  1

  white

  blue

  white/blue stripe

  2

  1

  blue/white stripe

  3

  2

  orange

  white/orange stripe

  4

  2

  orange/white stripe

  5

  3

  green

  white/green stripe

  6

  3

  green/white stripe

  7

  4

  brown

  white/brown stripe

  8

  4

  brown/white stripe

  9

  5

  slate

  white/slate stripe

  10

  5

  slate/white stripe

  11

  6

  red

  blue

  red/blue stripe

  12

  6

  blue/red stripe

  13

  7

  orange

  red/orange stripe

  14

  7

  orange/red stripe

  15

  8

  green

  red/green stripe

  16

  8

  green/red stripe

  17

  9

  brown

  red/brown stripe

  18

  9

  brown/red stripe

  19

  10

  slate

  red/slate stripe

  20

  10

  slate/red stripe

  21

  11

  black

  blue

  black/blue stripe

  22

  11

  blue/black stripe

  23

  12

  orange

  black/orange stripe

  24

  12

  orange/black stripe

  25

  13

  green

  black/green stripe

  26

  13

  green/black stripe

  27

  14

  brown

  black/brown stripe

  28

  14

  brown/black stripe

  29

  15

  slate

  black/slate stripe

  30

  15

  slate/black stripe

  31

  16

  yellow

  blue

  yellow/blue stripe

  32

  16

  blue/yellow stripe

  33

  17

  orange

  yellow/orange stripe

  34

  17

  orange/yellow stripe

  35

  18

  green

  yellow/green stripe

  36

  18

  green/yellow stripe

  37

  19

  brown

  yellow/brown stripe

  38

  19

  brown/yellow stripe

  39

  20

  slate

  yellow/slate stripe

  40

  20

  slate/yellow stripe

  41

  21

  violet

  blue

  violet/blue stripe

  42

  21

  blue/violet stripe

  43

  22

  orange

  violet/orange stripe

  44

  22

  orange/violet stripe

  45

  23

  green

  violet/green stripe

  46

  23

  green/violet stripe

  47

  24

  brown

  violet/brown stripe

  48

  24

  brown/violet stripe

  49

  25

  slate

  violet/slate stripe

  50

  25

  slate/violet stripe

  This is shown clearly in the following picture.

  25 pair UTP backbone cable color coding

  (b) More than 25-pair binder groups

  Multi-pair UTP cables that have more than 25 pairs organize the 25-pair binder groups in color-coded groups using the same color-coding sequence. This is shown in the following table.

  Pair Count

  Binder Group Color

  1—25

  White—blue

  26—50

  White—orange

  51—75

  White—green

  76—100

  White—brown

  101—125

  White—slate

  126—150

  Red–blue

  151—175

  Red—orange

  176—200

  Red—green

  201—225

  Red—brown

  226—250

  Red—Slate

  251—275

  Black—blue

  276—300

  Black—orange

  301—325

  Black—green

  326—350

  Black—brown

  351—375

  Black—slate

  376—400

  Yellow-blue

  Mor than 25 pair Multipair UTP backbone cable

  :: UTP Cable Connectors

  1) RJ45 Jack and Plug

  Four-pair UTP horizontal cables are terminated with an 8-position modular connector in the work area as shown below. The RJ45 jack is an 8-conductor, compact, modular jack used to terminate UTP data cable. RJ45 jacks are engineered to maintain specific Category 5, 5e, 6, or 6A performance, and therefore must match the category of the cable they are terminating.

  UTP-connector

  UTP cable connector

  :: 568A and 568B Wiring Standards

  When we refer to a jack or patch panel’s wiring connection, we refer to either the 568A or 568B wiring scheme. 568A and 568B wiring scheme define the pin-pair assignments for terminating UTP cable. These assignments define the pinout, or order of connections, for wires in 8P8C eight-pin modular connector plugs and sockets.

  In UTP cable, each pair is represented by a specific color. Pair 1 is Blue, Pair 2 is Orange, Pair 3 is Green, and Pair 4 is Brown. In each pair, one wire is a solid color, and the other is predominantly white with a color stripe. When terminating UTP cable, each pair corresponds to a specific pin on the IDC contacts of the jack or patch panel.

  The following charts illustrate the difference between 568A and 568B wiring scheme.

  Notice that the only difference between 568A and 568B is that pairs 2 and 3 (orange and green) are swapped. Both configurations wire the pins “straight through”, i.e., pins 1 through 8 on one end are connected to pins 1 through 8 on the other end.

  One can use cables wired according to either configuration in the same installation without significant problem. The primary thing one has to be careful is not to accidentally wire the ends of the same cable according to different configurations.

  UTP 68A and 568B Wiring Scheme

  Pin

  T568A Pair

  T568B Pair

  Wire

  T568A Color

  T568B Color

  Pins on plug face (socket is reversed)

  1

  3

  2

  tip

  60px-Wire_white_green_stripe.svg

  white/green stripe

  60px-Wire_white_orange_stripe.svg

  white/orange stripe

  RJ45 Plug 8P8C

  2

  3

  2

  ring

  60px-Wire_green.svg

  green solid

  60px-Wire_orange.svg

  orange solid

  3

  2

  3

  tip

  60px-Wire_white_orange_stripe.svg

  white/orange stripe

  60px-Wire_white_green_stripe.svg

  white/green stripe

  4

  1

  1

  ring

  60px-Wire_blue.svg

  blue solid

  60px-Wire_blue.svg

  blue solid

  5

  1

  1

  tip

  60px-Wire_white_blue_stripe.svg

  white/blue stripe

  60px-Wire_white_blue_stripe.svg

  white/blue stripe

  6

  2

  3

  ring

  60px-Wire_orange.svg

  orange solid

  60px-Wire_green.svg

  green solid

  7

  4

  4

  tip

  60px-Wire_white_brown_stripe.svg

  white/brown stripe

  60px-Wire_white_brown_stripe.svg

  white/brown stripe

  8

  4

  4

  ring

  60px-Wire_brown.svg

  brown solid

  60px-Wire_brown.svg

  brown solid