KNOW THE LINGO – WHAT IS A CATEGORY CABLE?By: Joseph D. Cornwall, CTS-D, CTS-I
AV Technology Evangelist — Legrand
This is one installment in a series of articles in which we'll lift the veils of misunderstanding from the lingo of the AV industry. You can see the rest of our Know the Lingo series in AV University, where you can earn AVIXA CTS certification renewal credits while you learn!
Technical lingo is a kind of shorthand that's used to express concepts common to a specialized area of focus. Technical lingo is important because it provides a precise or unique "shorthand" description of a device, effect or concept. Unfortunately, if you aren't comfortable and familiar with the lingo of a topic it can be a tall hurdle to communicate efficiently with folks who consider the jargon of their field to be "self-explanatory."
What is a Category Cable?The concept of Category cables was introduced by the Electronic Industries Alliance (EIA) in the 1980s and is now maintained by the Telecommunications Industry Association (TIA). In 1991, TIA released the TIA/EIA-568 standard. The standard works to align manufacturers and purchasers, facilitate interchangeability and improvement, and associate product performance with specific physical layer applications.
You simply can't be in the AV or IT industry and not run into Cat5e and Cat6 cables. The Cat, as you might know, is short for "Category." The term "Category" refers to the different levels of performance in signal bandwidth, attenuation and crosstalk associated with each cable's design.
Cat1 Cable - now defunctCategory 1 cables are a 2-pair copper UTP designed for POTS (plain old telephone systems). Capable of up to 1MHz bandwidth, Cat1 cables were once the most common telecommunications cables and were found in almost every home and office. Cat 1, however, isn't capable of carrying data due to its very constricted bandwidth.
Cat2 Cable - now defunctCategory 2 cables upped the game by doubling the conductor count to 4 twisted pairs. This design also increased bandwidth to a blistering 4Mbps, enough for teletype and fax communications! It's important to note that both Cat1 and Cat2 are name variations of Level 1 and Level 2 cables, which were originally defined by the low voltage distribution company Anixter International. Neither of these cables is defined in the TIA 568-C standard.
Cat3 Cable - now defunctCategory 3 cabling commonly known as Cat3 or "station wire," is an unshielded twisted pair cable designed to carry data up to 10 Mbps. It was used in the early 1990's for computer networking, in particular in a system known as "Token Ring." Cat3 is defined in the TIA 568-C standard and is still in use as a telephone wiring.
Cat4 Cable - now defunctCategory 4 cabling improved on Cat3 and offered up to 16 Mbps of bandwidth and was commonly used in both Token Ring and early 10Base-T networks. Cat4 is no longer recognized in TIA 568-C.
Cat5e CableCategory 5 enhanced cables are known as Cat5e and offer better crosstalk capability than the original Cat5. The original Cat5 is now a defunct cable standard. Cat5e supports up to 125MHz per twisted pair for a total of 1GHz bandwidth.
Cat5e is typically found in LAN applications such as 10Base-T, 100Base-TX (Fast Ethernet), and 1000Base-T (Gigabit Ethernet). Cat5e is also used for many AV and telephony applications. In fact, it may be the most ubiquitous UTP networking cables on the planet.
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Cat6 & Cat6a CablesCategory 6 (Cat6) is a standardized cable for Gigabit Ethernet and beyond. It’s backward compatible with Category 5/5e and Category 3 cable standards, but Cat6 has higher specifications for both crosstalk and system noise. It provides up to 250MHz bandwidth per pair. Cat6 may be specified in 1000Base-T (Gigabit Ethernet) and 10GBase-T (10-Gigabit Ethernet).
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Cat6a is an "augmented" improved Category 6 cable that supports up to 500MHz bandwidth per pair. Most installations that may have called for Cat6 in the past are now using Cat6a for its better performance parameters.
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Cat7 CablesTIA-568 doesn’t recognize a Category 7 cable.
There is an ISO/IEC (International Standards Organization/ International Electrotechnical Commission) European standard (ISO/IEC 11801) that defines a Class F cable with 600MHz bandwidth, and even a Class F augmented standard for up to 1000MHz bandwidth. Neither of these are recognized by TIA.
Cat8 CablesCategory 8 cables are fully shielded (F/UTP) and support transfer speeds up to 2 Ghz per pair (Cat8.1) for use in the most demanding applications. Category 8 is designed only for data centers where distances between switches and servers are short and it’s not intended for behind-the-walls structured wiring.
As Paul Harvey would say; "Now you know the rest of the story."