Category 5 cable

Category 5 cable (Cat 5) is a twisted pair cable for computer networks. 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 up to 2.5GBASE-T[1][2][3][4] but more commonly runs at 1000BASE-T (Gigabit Ethernet) speeds. Cat 5 is also used to carry other signals such as telephone and video.

Partially stripped cable showing the four twisted pairs (eight wires)

This cable is commonly connected using punch-down blocks and modular connectors. Most Category 5 cables are unshielded, relying on the balanced line twisted pair design and differential signaling for noise rejection.

Standards

The specification for category 5 cable is defined in ISO/IEC 11801, IEC 61156 and EN 50173.

The specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95.[5] 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.[6]

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.[7] This has exposed the manufacturers or installers of such fake cable to legal liabilities.[8]

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.[9] The bandwidth (100 MHz) and physical construction are the same between the two,[10] and most Cat 5 cables actually meet Cat 5e specifications, though they are not specifically certified as such.[11] The category 5 was deprecated in 2001 and superseded by the category 5e specification.[12]

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.[12] Category 6A cable provides 500 MHz bandwidth. Both variants are backwards compatible with Category 5 and 5e cables.

Termination
TIA/EIA-568-B.1-2001 T568A Wiring
PinPairWireColor
131 white/green
232 green
321 white/orange
412 blue
511 white/blue
622 orange
741 white/brown
842 brown
TIA/EIA-568-B.1-2001 T568B Wiring[13]
PinPairWireColor
121 white/orange
222 orange
331 white/green
412 blue
511 white/blue
632 green
741 white/brown
842 brown
A Cat 5e wall port showing the two wiring schemes: A for T568A, B for T568B
Category 5 patch cable in T568B wiring

Cable types, connector types and cabling topologies are defined by ANSI/TIA-568. Nearly always, 8P8C modular connectors (often referred to incorrectly as RJ45 connectors[14][15][16]) are used for connecting category 5 cable. The cable is terminated in either the T568A scheme or the T568B 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 networks such as Ethernet over twisted pair. The cable standard prescribes performance parameters for frequencies up to 100 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T (Gigabit Ethernet), 2.5GBASE-T. 10BASE-T and 100BASE-TX Ethernet connections require two wire pairs. 1000BASE-T and faster Ethernet connections require four wire pairs. Through the use of power over Ethernet (PoE), power can be carried over the cable in addition to Ethernet data.

Cat 5 is also used to carry other signals such as telephony and video.[17] 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.[18][19][20][21][22] 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 (10.2 Gbit/s) is one such scheme.[23]

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.

Electrical characteristics for a commercially available Cat 5e UTP cable product
PropertyNominalTolerance Unit ref
Characteristic impedance, 1–100 MHz100± 15Ω[24]
Characteristic impedance @ 100 MHz100± 5Ω[24]
DC loop resistance≤ 0.188Ω/m[24]
Propagation speed relative to the speed of light0.641[24]
Propagation delay5.30ns/m[24]
Delay skew < 100 MHz< 0.20ns/m[24]
Capacitance at 800 Hz52pF/m[24]
Max tensile load, during installation100N[24]
Wire diameter (24 AWG; 0.205 mm2))0.51mm[24]
Operating temperature−55 to +60°C[24]
Maximum DC operating voltage
(PoE uses max 57 V)[25]		125V[26]

Insulation

Outer insulation is typically polyvinyl chloride (PVC)[27] or low smoke zero halogen (LS0H).

Example materials used as insulation in the cable[28]
AcronymMaterial
PEPolyethylene
FPFoamed polyethylene
FEPFluorinated ethylene propylene
FFEPFoamed fluorinated ethylene propylene
AD/PEAir dielectric/polyethylene
LSZH or LS0H Low smoke, zero halogen
LSFZH or LSF0H Low smoke and fume, zero halogen

Bending radius

Most Category 5 cables can be bent at any radius exceeding approximately four times the outside diameter of the cable.[29][30]

Maximum cable segment length

The maximum length for a cable segment is 100 meters (330 ft) per TIA/EIA 568-5-A.[31] If longer runs are required, the use of active hardware such as a repeater or switch is necessary.[32][33] The specifications for 10BASE-T networking specify a 100-meter length between active devices.[34] This allows for 90 meters of solid-core permanent wiring, two connectors and two stranded patch cables of 5 meters, one at each end.[35]

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.[36]

Although cable assemblies containing 4 pairs are common, category 5 is not limited to 4 pairs. Backbone applications involve using up to 100 pairs.[37]

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.[38]

  Pair color[cm] per turnTurns per [m]
Blue1.3872
Green1.5365
Orange1.7856
Brown1.9452

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
United States and Canada fire certifications[39]
ClassPhraseDescriptionStandards
LSZHCommunications low-smoke zero halogenNES‑711, NES‑713, MIL‑C‑24643, UL 1685
CMPCommunications plenumInsulated with fluorinated ethylene propylene (FEP) and polyethylene (PE) and jacketed with low-smoke polyvinyl chloride (PVC), due to better flame test ratings.CSA FT6[40] or NFPA 262 (UL 910)
CMRCommunications riserInsulated with high-density polyolefin and jacketed with low-smoke polyvinyl chloride (PVC).

UL 1666

CMGCommunications general purposeCSA FT4
CMCommunicationsInsulated with high-density polyolefin, but not jacketed with PVC and therefore is the lowest of the three in flame resistance.UL 1685 (UL 1581, Sec. 1160) Vertical-Tray
CMXCommunications residentialUL 1581, Sec. 1080 (VW-1)
CMHCSA FT1

Some cables are "UV-rated" or "UV-stable" meaning they can be exposed to outdoor UV radiation without significant degradation.[41]

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 spaces where PVC is not allowed.[42]

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 likelihood should be minimized.

References
  1. Cooney, Michael (2016-09-27). "IEEE sets new Ethernet standard that brings 5X the speed without disruptive cable changes". Network World. Retrieved 2021-01-19.
  2. Anthony, Sebastian (2016-09-29). "Here comes 5Gbps networking over standard cables". Ars Technica. Retrieved 2021-01-18.
  3. Smith, Ryan. "At Last, a 2.5Gbps Consumer Network Switch: QNAP Releases QSW-1105-5T 5-Port Switch". www.anandtech.com. Retrieved 2021-01-19.
  4. "IEEE P802.3bz 2.5/5GBASE-T Task Force". www.ieee802.org. Retrieved 2021-01-19.
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  6. "Ethernet Cable Identification and Use". Donutey. Archived from the original on 2011-07-10. Retrieved 2011-04-01.
  7. "APPLICATION NOTE Copper Clad Aluminum(CCA) Cables". Fluke Networks. 26 December 2013. Retrieved 2021-04-07.
  8. "Potential Legal Liabilities for Manufacturers and Installers of Category Communications Cables Made with Copper Clad Aluminum Conductors". Communications Cable and Connectivity Association, Inc. (CCCA). Retrieved 2021-04-07.
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  12. "Voice and Data Cabling & Wiring Installations". Retrieved 2013-05-12.
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  14. Trulove 2005, pp. 23, 132: ‘Designing LAN Wiring Systems: The 8-pin modular jack is sometimes referred to as an "RJ-45", because the connector/jack components are the same. However, RJ-45 actually applies to a special purpose jack configuration that is not used in LAN or standard telephone wiring. […] Work Area Outlets: Modular jacks are often referred to as "RJ-45" jacks. This is not really the correct moniker, although it is in very common use.’
  15. Oliviero, Andrew; Woodward, Bill (July 20, 2009). "Connectors". Cabling: The Complete Guide to Copper and Fiber-Optic Networking (4th ed.). Sybex. p. 294. ISBN 978-0-470-47707-6. The RJ (registered jack) prefix is one of the most widely (and incorrectly) used prefixes in the computer industry; nearly everyone, including people working for cabling companies, is guilty of referring to an eight-position modular jack (sometimes called an 8P8C) as an RJ-45.
  16. Semenov, Andrey B.; Strizhakov, Stanislav K.; Suncheley, Igor R. (October 3, 2002). "Electrical Cable Connectors". Structured cable systems. Springer. p. 129. ISBN 3-540-43000-8. The traditional 8-contact connector, which is called Western Plug, 8PMJ (8-position modular jack), 8P8C (8 position 8 conductor), or somewhat incorrectly RJ-45, is used widely in SCS practice.
  17. "Transmitting video over CAT 5 cable". EE Times. 2005-06-08. Retrieved 2013-12-07.
  18. "Hack your House: Run Both Ethernet and Phone Over Existing Cat 5 Cable". Retrieved 2016-08-15.
  19. "LAN and Telephones". zytrax. October 21, 2015. Since 10base-T or 100base-TX wiring uses 2 pairs (4 wires) and each analog phone connection uses a single pair (2 wires) you can, subject to limitations, run 2 telephone connections and LAN traffic on category 5(e) wiring.
  20. "Cable Sharing in Commercial Building Environments: Reducing Cost, Simplifying Cable Management, and Converging Applications onto Twisted-Pair Media". Siemon. Retrieved 2014-04-28.
  21. "RJ45/RJ11 Network Cable Splitters for Ethernet and Phone Line Sharing". carry one old fashioned analog telephone signal and one 10/100Mbps Ethernet signal by the same single network cable.
  22. "ATS 10/100 Base T Splitter Adapters". Duxcw.com. Retrieved 2014-08-17.
  23. HDBaseT Alliance (January 9, 2013). "HDBaseT Alliance Shows the Future of Connected Home Entertainment at CES 2013". Retrieved 2017-10-31.
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  25. IEEE 802.3at-2009 Table 33-11
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  27. "Specialized Ethernet Cable" (PDF). CableWholesale. August 2016.
  28. "UTP-STP Cable" (PDF). Retrieved 2016-08-18.
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  30. "Category 5". Archived from the original on 2013-06-01. Retrieved 2013-05-12.
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  32. "UTP technology" (PDF). Extron Electronics. 2001. Archived from the original (PDF) on 2013-05-11. Retrieved 2013-05-12.
  33. "CAT 5e Cable Wiring Schemes". B&B Electronics. Archived from the original on 2012-10-05.
  34. "IEEE Std 802.3-2008". Institute of Electrical and Electronics Engineers. 2008. Table 13-1. {{cite journal}}: Cite journal requires |journal= (help)
  35. "Horizontal Cabling". The Network Encyclopedia. Retrieved 2013-05-12.
  36. "ANSI/TIA/EIA-568-B.2-2001, Commercial Building Telecommunications Cabling Standard" (PDF). p. 6 ¶4.3.2.
  37. As noted in ANSI/TIA/EIA-568-B-2 standard for backbone applications
  38. Brooke Clarke, "CAT 5 Wire Measurements", Transmission Line Zo vs. Frequency, retrieved 2017-08-12
  39. "Technical Information" (PDF). Belden. p. 22.20. Archived from the original (PDF) on 2006-10-20.
  40. "CSA Flame Test Ratings". Retrieved 2013-05-12.
  41. CIBSE (2000). "Understanding Building Integrated Photovoltaics - CIBSE TM25 - 5.8 Legislation. The Chartered Institution of Building Services Engineers (CIBSE)". app.knovel.com. Retrieved 2022-03-29.
  42. "What are the differences between PVC, riser and plenum-rated cables?". Archived from the original on 2011-07-13.

Further reading
  • Trulove, James (December 19, 2005), LAN wiring (3rd ed.), McGraw-Hill Professional, ISBN 0-07-145975-8
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