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.
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.
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]
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5e specifications, though they are not specifically certified as such.[11] The category 5 was deprecated in 2001 and superseded by the category 5e specification.[12]
