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Category 3 cable, commonly known as Cat 3 or station wire, and less commonly known as VG or voice-grade (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.

Although designed to reliably carry data up to 10 Mbit/s, modern data networks run at much higher speeds, and Cat 5e or better cable is generally used for new installations. Cat 3 cables may have 2, 3, 4, or more pairs.

Networking

Cat 3 was widely used in computer networking 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 Cat 3 cable, but the later 802.3at Type 2 high-power variation does not. 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.

Dedicated 100BASE-T4 networks, supporting 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 and Intel LinkBuilder FMS 100 T4. 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 Cat 5e cable required by 100BASE-TX. Cat 5e or Cat 6 is now used for all modern structured cabling installations. Many large institutions have policies that any upgrade to a network using Cat 3 must involve upgrading to Cat 5e.

See also

• Copper cable certification

References

1. CompTIA Network+ Review Guide: Exam N10-008. John Wiley & Sons. 28 September 2021. ISBN 978-1-119-80696-7.
2. Evolution of Cabling Standards: TIA/EIA, ISO/IEC, CENELEC
3. Standards Update
4. "CCNA: Network Media Types". Cisco Systems. Retrieved 2017-09-05.
5. Spurgeon, Charles E (2000). Ethernet: the definitive guide. O'Reilly. p. 125. ISBN 9781565929524.
6. Williams, Lawrence (2020-03-01). "Ethernet Cables Types: Cat 3, 5, 5e, 6, 6a, 7, 8 Wires Explained". www.guru99.com. Retrieved 2023-04-09.
7. Woodward, Bill (5 March 2014). Cabling: The Complete Guide to Copper and Fiber-Optic Networking. John Wiley & Sons. p. 219. ISBN 978-1-118-80738-5. Retrieved 18 November 2024.
8. IEEE 802.3at-2009, clause 33.1.1c
9. Gigabit over Cat3, WTF
10. CONVERTING HOME TELEPHONE WIRING TO ETHERNET
11. How to convert your telephone line to an internet line: A complete guide
12. IBM 8225 Fast Ethernet Stackable Hub
13. "3Com Product End of Sale dates" (PDF). Hewlett Packard Enterprise.
14. "Intel Express 100BASE-T4 User's Manual". Manualzz.
15. "University of Wisconsin – Standards for the Installation of New Data/Voice Jacks". Retrieved 2013-09-17.

External links

• How Low Voltage Cable is Made - Cat5e, Cat6, Cat3 and OSP

• Ethernet cables