View source for Category 3 cable

{{Short description|Unshielded twisted pair cable used in telephone wiring}}
{{Twisted pair categories}}
[[File:Cat 3 cable 3.jpg|thumb|Cross section of a 25-pair category 3 cable]]
[[File:CAT-3 cable 5.jpg|thumb|A two-pair Cat 3 cable]]

'''Category&nbsp;3 cable''', commonly known as '''{{no wrap|Cat 3}}''' or '''station wire''', and less commonly known as '''VG''' or '''voice-grade'''<ref>{{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> (as, for example, in [[100BaseVG]]), is an [[unshielded twisted pair]] (UTP) cable used in [[telephone]] wiring. It is part of a family of standards defined jointly by the [[Electronic Industries Alliance]] (EIA) and the [[Telecommunications Industry Association]] (TIA) and published in [[TIA/EIA-568-B]].<ref>[https://grouper.ieee.org/groups/802/3/tutorial/july98/kish_070798.pdf Evolution of Cabling Standards: TIA/EIA, ISO/IEC, CENELEC]{{sps|date=November 2022}}</ref><ref>[https://www.ieee802.org/3/minutes/jul99/B2_0799.pdf Standards Update]{{sps|date=November 2022}}</ref>

Although designed to reliably carry data up to {{nowrap|10 Mbit/s}},<ref>{{cite web |url=http://www.ciscopress.com/articles/article.asp?p=31276 |title=CCNA: Network Media Types |publisher=[[Cisco Systems]] |access-date=2017-09-05}}</ref> modern data networks run at much higher speeds, and {{no wrap|[[Cat 5e]]}} or better cable is generally used for new installations.<ref>{{cite book |title=Ethernet: the definitive guide |last=Spurgeon |first=Charles E |date=2000 |publisher=O'Reilly |isbn=9781565929524 |page=125}}</ref> Cat 3 cables may have 2, 3, 4, or more pairs.<ref>{{Cite web |last=Williams |first=Lawrence |date=2020-03-01 |title=Ethernet Cables Types: Cat 3, 5, 5e, 6, 6a, 7, 8 Wires Explained |url=https://www.guru99.com/ethernet-cables-types.html |access-date=2023-04-09 |website=www.guru99.com |language=en-US}}</ref><ref>{{cite book |last1=Woodward |first1=Bill |title=Cabling: The Complete Guide to Copper and Fiber-Optic Networking |date=5 March 2014 |publisher=John Wiley & Sons |isbn=978-1-118-80738-5 |page=219 |url=https://www.google.com/books/edition/Cabling/BjYKAwAAQBAJ?hl=en&gbpv=1&pg=PA219 |access-date=18 November 2024 |language=en}}</ref>

==Networking==
{{no wrap|Cat 3}} was widely used in [[computer network]]ing in the early 1990s for [[10BASE-T]] Ethernet and, to a much lesser extent, for [[100BaseVG]] Ethernet, [[Token Ring]] and [[100BASE-T4]]. The original [[Power over Ethernet]] 802.3af specification supports the use of {{no wrap|Cat 3}} cable, but the later 802.3at Type 2 high-power variation does not.<ref name="33.1.1c">IEEE 802.3at-2009, clause 33.1.1c</ref> In some use cases and for short distances, Cat 3 may be capable of carrying 100BASE-TX (2 pairs) or even 1000BASE-T (4 pairs). Such use cases include hobbyist retrofitting short home telephone Cat 3 networks for Ethernet.<ref>[https://www.reddit.com/r/networking/comments/1w71mh/gigabit_over_cat3_wtf/ Gigabit over Cat3, WTF]{{sps|date=November 2022}}</ref><ref>[https://www.youtube.com/watch?v=Bx98ACGSSZs CONVERTING HOME TELEPHONE WIRING TO ETHERNET]{{sps|date=November 2022}}</ref><ref>[https://www.youtube.com/watch?v=hvUH-Cqtp6w How to convert your telephone line to an internet line: A complete guide]{{sps|date=November 2022}}</ref>

Dedicated 100BASE-T4 networks, supporting {{nowrap|100 Mbit/s}} over Cat 3, appear to have been a rarity as very few network interface controllers and switches were ever released. Some examples include the [[3com]] 3C250-T4 Superstack II HUB 100, [[IBM]] 8225 Fast Ethernet Stackable Hub<ref>[https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS196-117&infotype=AN&mhq=IBM%20Network%20Station%208361%20Series%20100&mhsrc=ibmsearch_a&subtype=CA IBM 8225 Fast Ethernet Stackable Hub]</ref> and [[Intel]] LinkBuilder FMS 100 T4.<ref>{{cite web|url=https://techlibrary.hpe.com/docs/products/eos/3Com-End-of-Sale%20dates.pdf|title=3Com Product End of Sale dates|website=[[Hewlett Packard Enterprise]]}}</ref><ref>{{cite web | url=https://manualzz.com/doc/3244934/intel-express-100base-t4-user-s-manual | title=Intel Express 100BASE-T4 User's Manual | website=Manualzz}}</ref> The same applies to [[network interface controller]] cards. Bridging 100BASE-T4 with 100BASE-TX required additional network equipment.

==Replacement==
Starting in the mid-1990s, new [[structured cabling]] installations were often built with the higher performing {{no wrap|Cat 5e}} cable required by [[100BASE-TX]]. {{no wrap|Cat 5e}} or {{no wrap|Cat 6}} is now used for all modern structured cabling installations. Many large institutions have policies that any upgrade to a network using {{no wrap|Cat 3}} must involve upgrading to {{no wrap|Cat 5e}}.<ref>{{cite web |url=https://kb.wisc.edu/ns/page.php?id=13372 |title=University of Wisconsin – Standards for the Installation of New Data/Voice Jacks |accessdate=2013-09-17}}</ref>

==See also==
* [[Copper cable certification]]

==References==
{{Reflist}}

==External links==
* [https://discountlowvoltage.blogspot.com/2009/11/how-low-voltage-cable-is-made-cat5e.html How Low Voltage Cable is Made - Cat5e, Cat6, Cat3 and OSP]

{{UTP Cable Standards}}

{{DEFAULTSORT:Category 3 Cable}}
[[Category:Ethernet cables]]