Editing Twisted pair (section)

==Types==
{{see also|ISO/IEC 11801}}

===Analog telephone===
Before digital communication and Ethernet became widespread there was no international standard for telephone cable. Standards were set at a national level. For instance, in the UK the [[General Post Office]] specified CW1293 and CW1308 cables. CW1308 was a similar specification to the earlier CW1293 but with an improved color code. CW1293 used mostly solid colors on the cores making it difficult to identify the pair it was twisted with without stripping back a large amount of sheath. To solve this problem. CW1308 has narrow rings of the paired color printed over the base color. Both cables are a similar standard to category 3 cable.<ref>{{citation |author=Stephen Roberts |title=Telephone Installation Handbook |pages=32–34 |publisher=Elsevier |date=2001 |isbn=0080521487}}</ref><ref>{{citation |author=Barry J. Elliot |title=Designing a Structured Cabling System to ISO 11801 |page=269 |publisher=CRC Press |date=2002 |isbn=0824741307}}</ref> Cables with categories 3 through 7 have 4 twisted pairs.<ref>{{cite book | url=https://books.google.com/books?id=d6nro_tNEpIC&dq=category+3+cable+pairs&pg=PA57 | isbn=978-0-08-049742-6 | title=Newnes Data Communications Pocket Book | date=19 April 2002 | publisher=Elsevier }}</ref>

Prior to the common use of polyethylene and other plastics for insulation, telephone twisted pair cable was insulated with waxed paper or cotton with a wax coating applied to the copper. The overall sheath of this type of cable was usually lead. This style of cable came into use in the late 19th century shortly after the invention of the telephone.<ref>''Telephony'', vol. 153, p. 118, Telephone Publishing Corporation 1957.</ref> The cable termination in termination boxes were sealed with molten wax or a resin to prevent the ingress of moisture which would seriously degrade the insulating properties of the paper insulation.<ref>''Paper Maker and British Paper Trade Journal'', vol. 83-84, p. 294, November 1, 1932 {{oclc|10634178}}</ref> However, such seals made future maintenance and changes more difficult. These cables are no longer made but are still occasionally encountered in old buildings and in various external areas, commonly rural villages.

===Building infrastructure===
{| class="wikitable sortable"
|+Standard types of twisted pair cabling
|-
! Name
! Typical construction
! Bandwidth
! Applications
! Notes
|-
| [[Category 1 cable|Level 1]]
|
| 400&nbsp;kHz
| Telephone and modem lines
| Not described in EIA/TIA recommendations. Unsuitable for modern systems.<ref name="cisco">{{cite web|title=CCNA: Network Media Types|url=http://www.ciscopress.com/articles/article.asp?p=31276}}</ref>
|-
| [[Category 2 cable|Level 2]]
|
| 4&nbsp;MHz
| Older terminal systems, e.g. [[IBM 3270]]
| Not described in EIA/TIA recommendations. Unsuitable for modern systems.<ref name=cisco />
|-
| [[Category 3 cable|Cat 3]]
| UTP<ref name="dcuse" />
| 16&nbsp;MHz<ref name="dcuse" />
| [[10BASE-T]], [[100BASE-T4]]<ref name="dcuse" />
| Described in EIA/TIA-568. Unsuitable for speeds above {{nowrap|16 Mbit/s}}. Now mainly for telephone cables.<ref name="dcuse" />
|-
| [[Category 4 cable|Cat 4]]
| UTP<ref name="dcuse" />
| 20&nbsp;MHz<ref name="dcuse" />
| {{nowrap|16 Mbit/s}} [[Token Ring]]<ref name="dcuse" />
| Not commonly used<ref name="dcuse" />
|-
| [[Cat 5]]
| UTP<ref name="dcuse" />
| 100&nbsp;MHz<ref name="dcuse" />
| [[100BASE-TX]], [[1000BASE-T]]<ref name="dcuse" />
| Common for current LANs. Superseded by Cat 5e, but most Cat 5 cables meet Cat 5e standards.<ref name="dcuse" /> Limited to 100&nbsp;m between equipment.
|-
| [[Cat 5e]]
| UTP,<ref name="dcuse" /> F/UTP, U/FTP<ref>{{Cite web|url=https://sewelldirect.com/learning-center/utp-vs-stp-cable|title=Using UTP Cat5e vs. STP Cat5e Cable - SewellDirect.com|website=sewelldirect.com|access-date=2018-08-19}}</ref>
| 100&nbsp;MHz<ref name="dcuse" />
| [[1000BASE-T]], [[2.5GBASE-T]]<ref name="dcuse" />
| Enhanced Cat 5. Common for current LANs. Same construction as Cat 5, but with better testing standards.<ref name="dcuse" /> Limited to 100&nbsp;m between equipment.
|-
| [[Cat 6]]
| UTP,<ref name="dcuse" /> F/UTP, U/FTP<ref>{{Cite news|url=https://customcable.ca/cat5-vs-cat6/|title=CAT3 vs. CAT5 vs. CAT6 - CustomCable|date=2011-12-24|work=CustomCable|access-date=2018-08-19|language=en-US}}</ref>
| 250&nbsp;MHz<ref name="dcuse" />
| [[5GBASE-T]], [[10GBASE-T]]
| ISO/IEC 11801 2nd Ed. (2002), ANSI/TIA 568-B.2-1. Limited to 55&nbsp;m distance at 10GBASE-T
|-
| [[Cat 6A]]
| UTP, F/UTP, U/FTP, S/FTP
| 500&nbsp;MHz
| [[5GBASE-T]], [[10GBASE-T]]
| Improved standards, tested to 500&nbsp;MHz. Full 100&nbsp;m distance at 10GBASE-T ISO/IEC 11801 2nd Ed. Am. 2. (2008), ANSI/TIA-568-C.1 (2009)
|-
| [[Category 7|Cat 7]]
| S/FTP, F/FTP
| 600&nbsp;MHz<ref name="CompTIA">{{cite book | url=https://books.google.com/books?id=iJVFEAAAQBAJ&dq=category+3+cable+frequency&pg=PT142 | isbn=978-1-119-80696-7 | title=CompTIA Network+ Review Guide: Exam N10-008 | date=28 September 2021 | publisher=John Wiley & Sons }}</ref>
| {{dunno}}
| ISO/IEC 11801 2nd Ed. (2002). Only with [[GG45]] or [[TERA]] connectors. It is not recognized by the [[Electronic Industries Alliance|EIA]]/[[Telecommunications Industry Association|TIA]].
|-
| [[Category 7A|Cat 7<sub>A</sub>]]
| S/FTP, F/FTP
| 1&nbsp;GHz<ref name="CompTIA" />
| {{dunno}}
| ISO/IEC 11801 2nd Ed.&nbsp;Am.&nbsp;2. (2008). Only with GG45 or TERA connectors. It is not recognized by the EIA/TIA.
|-
| [[Cat 8.1]]
| F/UTP, U/FTP
| 2&nbsp;GHz<ref name="CompTIA" />
| [[25GBASE-T]], [[40GBASE-T]]
| ANSI/TIA-568-C.2-1, ISO/IEC 11801-1:2017
|-
| [[Cat 8.2]]
| S/FTP, F/FTP
| 2&nbsp;GHz
| [[25GBASE-T]], [[40GBASE-T]]
| ISO/IEC 11801-1:2017
|}

===Loaded===
A loaded twisted pair has intentionally added [[inductance]] and was formerly common practice on telecommunication lines. The added inductors are known as [[load coil]]s and reduce attenuation for [[voiceband]] frequencies but increase it on higher frequencies. Load coils reduce distortion in voiceband on very long lines.<ref>{{cite web|url=http://www.cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a00800a8663.shtml|website=Cisco.com|title=Understanding Line Impairments|access-date=2012-06-04}}</ref> In this context a line without load coils is referred to as an unloaded line.

===Bonded===
A bonded twisted pair is a construction variant in which the two wires of each pair are bonded together for the length of the cable. Pioneered by [[Belden (electronics company)|Belden]], it is intended to help assure configuration consistency during and after installation. One key benefit is that the noise immunity performance of the cable can be protected despite potentially rough handling.<ref>{{cite web |title=Contractor Field-Testing Survey Reveals Performance-Related Cost Savings Using Bonded-Pair Cables |url=http://www.belden.com/docs/upload/TB67.pdf |publisher=Belden |access-date=13 August 2016}}</ref> The enhanced performance may be unnecessary and bonding reduces the flexibility of the cable and makes it prone to failure where it is flexed.<ref>{{cite web |title=Bonded Pair Cable |publisher=Turck |url=https://www.turck.us/static/media/downloads/WP_Bonded_Pair_Cable.pdf |access-date=2019-04-08 }}</ref>

===Twisted ribbon cable===
[[File:Scsi intern hd68 lvd term.jpg|thumb|upright|Twisted ribbon cable used for [[Parallel SCSI]] connections]]

A twisted ribbon cable is a variant of standard [[ribbon cable]] in which adjacent pairs of conductors are bonded and twisted together. The twisted pairs are then lightly bonded to each other in a ribbon format. Periodically along the ribbon, there are short sections with no twisting where connectors may be attached using the usual ribbon cable [[insulation-displacement connector|IDC]] techniques.<ref>{{cite web |title=3M Twisted Pair Flat Cable |url=http://multimedia.3m.com/mws/media/22068O/3mtm-twisted-pair-flat-cable-050-28awg-1700-series-ts0115.pdf |publisher=3M |access-date=13 August 2016 }}</ref>

===Solid-core vs. stranded cable===
[[File:110-punch-block-IDC-0a.jpg|thumb|upright|A [[punch-down block]]]]

A solid-core cable uses one solid wire per conductor and in a four-pair cable, there would be a total of eight solid wires.<ref name="dcuse">{{cite web|title=Comparison between CAT5, CAT5e, CAT6, CAT7 Cables|url=http://discountcablesusa.com/ethernet-cables100.htm| archive-url=https://web.archive.org/web/20200602172021/http://discountcablesusa.com/ethernet-cables100.html| archive-date=2020-06-02| url-status=dead| access-date=2022-07-18}}</ref> [[Stranded wire|Stranded cable]] uses multiple wires wrapped around each other in each conductor and in a four-pair with seven strands per conductor cable, there would be a total of 56 wires (2 per pair × 4 pairs × 7 strands).<ref name="dcuse" />

Solid core cable is intended for permanently installed runs ([[Structured cabling#permanent link|permanent link]]). It is less flexible than stranded cable and is more prone to failure if repeatedly flexed due to [[work hardening]]. Stranded cable is used at [[patch panel]]s and for connections from wall ports to end devices ([[patch cord]] or drop cable), as it resists cracking of the conductors.

Connectors are designed differently for solid core than for stranded. Use of a connector with the wrong cable type can lead to unreliable cabling. Plugs designed for solid and stranded cores are readily available, and some vendors even offer plugs designed for use with both types. The [[punch-down block]]s on patch-panel and wall-port jacks are designed for use with solid core cable. These work via the [[Insulation-displacement connector|insulation-displacement method]], whereby the device pierces the sides of the insulation and "bites" into the copper conductor to form a connection. Punchdown blocks are used as patch panels or as break-out boxes, for twisted pair cable.