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53-450: As of 2024, the revision status of the standard is ANSI/TIA-568-E , published 2020, which replaced ANSI/TIA-568-D of 2015, revision C of 2009, revision B of 2001, and revision A of 1995, and the initial issue of 1991, which are now obsolete. Perhaps the best-known features of ANSI/TIA-568 are the pin and pair assignments for eight-conductor 100-ohm balanced twisted pair cabling. These assignments are named T568A and T568B . ANSI/TIA-568

106-496: A distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made. For example, the Main Distribution Frame (MDF) located at a telephone central office terminates the cables leading to subscribers on the one hand, and cables leading to active equipment (such as DSLAMs and telephone switches ) on the other. Service is provided to a subscriber by manually wiring

159-468: A twisted pair (called a jumper wire) between the telephone line and the relevant DSL or POTS line circuit. In broadcast engineering , a distribution frame is a location within an apparatus room through which all signals ( audio , video, or data) pass, with the ability to arbitrarily route and connect sources and destinations between studios and other internal and external points. Connections can either be soldered, or made using terminal blocks. Because

212-690: A cable system suitable for higher rates of data transmission. Category 3 cable was suitable for telephone circuits and data rates up to 16 million bits per second. Category 5 cable , with more restrictions on attenuation and cross talk, has a bandwidth of 100 MHz. The 1995 edition of the standard defined Categories 3, 4, and 5. Categories 1 and 2 were excluded from the standard since these categories were only used for voice circuits, not for data. The current revision includes Category 5e (100 MHz), 6 (250 MHz), 6A (500 MHz), and 8 (2,000 MHz). Categories 7 and 7A were not officially recognized by TIA and were generally only used outside

265-455: A connector (a plug or a socket) and the wires in a cable. Pinouts are critical because cables do not function if the pinouts at their two ends aren't correctly matched. The standard specifies how to connect eight-conductor 100-ohm balanced twisted-pair cabling, such as Category 5 cable , to 8P8C modular connectors (often referred to as RJ45 connectors). The standard defines two alternative pinouts: T568A and T568B. ANSI/TIA-568 recommends

318-443: A distribution frame or router , which can handle audio from multiple studios (even for multiple co-located radio or TV stations) at the same time. Multiple smaller frames, such as one for each studio, can be linked together with fibre-optics (which also helps eliminate ground loops ), or with gigabit Ethernet . This has the advantage of not having to route dozens of feeds through walls (and sometimes floors and ceilings ) to

371-402: A four-pair cable, there would be a total of eight solid wires. Stranded cable uses multiple wires wrapped around each other in each conductor and in a four-pair with seven strands per conductor cable, there would be a total of 56 wires (2 per pair × 4 pairs × 7 strands). Solid core cable is intended for permanently installed runs ( permanent link ). It is less flexible than stranded cable and

424-473: A method called wire transposition , to cancel out the interference. In wire transposition, the wires exchange position once every several poles. In this way, the two wires would receive similar EMI from power lines. This represented an early implementation of twisting, with a twist rate of about four twists per kilometre , or six per mile . Such open-wire balanced lines with periodic transpositions still survive today in some rural areas. Twisted-pair cabling

477-586: A point for the consolidation of all horizontal cabling, which extends in a star topology to individual work areas such as cubicles and offices. Under TIA/EIA-568-B, maximum allowable horizontal cable distance is 90 meters of installed twisted-pair cabling, with 100 meters of maximum total length including patch cords. No patch cord should be longer than 5 meters. Optional consolidation points are allowable in horizontal cables, often appropriate for open-plan office layouts where consolidation points or media converters may connect cables to several desks or via partitions. At

530-405: A resin to prevent the ingress of moisture which would seriously degrade the insulating properties of the paper insulation. However, such seals made future maintenance and changes more difficult. These cables are no longer made but are still occasionally encountered in old buildings and in various external areas, commonly rural villages. A loaded twisted pair has intentionally added inductance and

583-523: A separate earth ground wire, but some urban exchanges have about 250,000 wires on their MDF . Installing and rewiring these jumpers is a labour-intensive task, leading to attempts in the industry to devise so-called active distribution frames or Automated Main Distribution Frames . The principal issues which stand in the way of their widespread adoption are cost and reliability. Newer digital mixing consoles can act as control points for

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636-427: A similar topology. Many people refer to cross-connects by their telecommunications names: distribution frames (with the various hierarchies called main distribution frames ( MDFs ), intermediate distribution frames ( IDFs ) and wiring closets ). Backbone cabling is also used to interconnect entrance facilities (such as telco demarcation points ) to the main cross-connect. Horizontal cross-connects provide

689-402: Is a variant of standard ribbon cable in which adjacent pairs of conductors are bonded and twisted together. The twisted pairs are then lightly bonded to each other in a ribbon format. Periodically along the ribbon, there are short sections with no twisting where connectors may be attached using the usual ribbon cable IDC techniques. A solid-core cable uses one solid wire per conductor and in

742-636: Is more prone to failure if repeatedly flexed due to work hardening . Stranded cable is used at patch panels and for connections from wall ports to end devices ( patch cord or drop cable), as it resists cracking of the conductors. Connectors are designed differently for solid core than for stranded. Use of a connector with the wrong cable type can lead to unreliable cabling. Plugs designed for solid and stranded cores are readily available, and some vendors even offer plugs designed for use with both types. The punch-down blocks on patch-panel and wall-port jacks are designed for use with solid core cable. These work via

795-473: Is often grouped into sets of 25 pairs according to a standard 25-pair colour code originally developed by AT&T Corporation . A typical subset of these colours (white/blue, blue/white, white/orange, orange/white) shows up in most UTP cables. The cables are typically made with copper wires measured at 22 or 24 American Wire Gauge (AWG) (0.644 or 0.511 mm²), with the coloured insulation typically made from an insulator such as polyethylene or FEP and

848-482: Is on telegraph lines. Telephone companies converted to balanced circuits , which had the incidental benefit of reducing attenuation , hence increasing range. As electrical power distribution became more commonplace, this measure proved inadequate. Two wires, strung on either side of cross bars on utility poles , shared the route with electrical power lines . Within a few years, the growing use of electricity again brought an increase of interference, so engineers devised

901-433: Is that the currents induced in each of the two wires are very nearly equal. The twisting ensures that the two wires are on average the same distance from the interfering source and are affected equally. The noise thus produces a common-mode signal which can be cancelled at the receiver by detecting the difference signal only, the latter being the wanted signal. Common-mode rejection starts to fail on untwisted wires when

954-470: Is to provide recommended practices for the design and installation of cabling systems that will support a wide variety of existing and future services. Developers hope the standards will provide a lifespan for commercial cabling systems in excess of ten years. This effort has been largely successful, as evidenced by the definition of Category 5 cabling in 1991, a cabling standard that (mostly) satisfied cabling requirements for 1000BASE-T , released in 1999. Thus,

1007-517: Is used, it connects to pair 2 (orange/white) of jacks wired to T568A but to pair 3 (green/white) in jacks wired to T568B. This makes T568B potentially confusing in telephone applications. Because of different pin pairings, the RJ25 and RJ61 plugs cannot pick up lines 3 or 4 from T568A or T568B without splitting pairs. This would most likely result in unacceptable levels of hum, crosstalk, and noise. The original idea in wiring modular connectors, as seen in

1060-492: The baseband of television signals, UTP is now used in some video applications, primarily in security cameras . As UTP is a balanced transmission line, a balun is needed to connect to unbalanced equipment, for example any using BNC connectors and designed for coaxial cable. Twisted pair cables may incorporate shielding in an attempt to prevent electromagnetic interference. Shielding provides an electrically conductive barrier to attenuate electromagnetic waves external to

1113-474: The insulation-displacement method , whereby the device pierces the sides of the insulation and "bites" into the copper conductor to form a connection. Punchdown blocks are used as patch panels or as break-out boxes, for twisted pair cable. Twisted pair has the following useful attributes: Twisted pair has the following limitations: [REDACTED] Media related to Twisted-pair cables at Wikimedia Commons Distribution frame In telecommunications ,

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1166-458: The registered jacks , was that the first pair would go in the center positions, the next pair on the next-innermost ones, and so on. Also, signal shielding would be optimized by alternating the live and earthy pins of each pair. The terminations diverge slightly from this concept because, on the eight-position connector, the resulting arrangement of conductors would separate the outermost pair, impairing balanced line performance too much to meet

1219-400: The 1880s electric trams were installed in many cities, which induced noise into these circuits. In some countries, the tram companies were held responsible for disruption to existing telegraph lines and had to pay for remedial work. For new installations, however, it was necessary to protect against existing trams from the outset. Interference on telephone lines is even more disruptive than it

1272-503: The T568A pinout for horizontal cables. This pinout is compatible with the 1-pair and 2-pair Universal Service Order Codes (USOC) pinouts. The U.S. Government requires it in federal contracts. The standard also allows, only in certain circumstances, the T568B pinout "if necessary to accommodate certain 8-pin cabling systems", i.e. when, and only when, adding to an existing installation that used

1325-539: The T568B wiring pattern before it was defined, being those that pre-dated ANSI/TIA-568 and used the previous AT&T 258A (Systimax) standard. In the 1990s, when the original TIA/EIA-568 was published, the most widely installed wiring pattern in UTP cabling infrastructure was that of AT&T 258A (Systimax), hence the inclusion of the same wiring pattern (as T568B) as a secondary option for use in such installations. Many organizations still use T568B out of inertia. The colors of

1378-508: The TIA. EIA no longer exists, hence EIA has been removed from the name. The first version of the standard, EIA/TIA-568, was released in 1991. The standard was updated to revision A in 1995. The demands placed upon commercial wiring systems increased dramatically over this period due to the adoption of personal computers and data communication networks and advances in those technologies. The development of high-performance twisted pair cabling and

1431-513: The United States. Category 8 was published with ANSI/TIA‑568‑C.2‑1 (June 2016) to meet the performance specification intended by Category 7. ANSI/TIA-568-D defines a hierarchical cable system architecture, in which a main cross-connect ( MCC ) is connected via a star topology across backbone cabling to intermediate cross-connects ( ICCs ) and horizontal cross-connects ( HCCs ). Telecommunications design traditions utilized

1484-494: The benefits of twisting. For this reason, it is commonly specified that, at least for cables containing small numbers of pairs, the twist rates must differ. In contrast to shielded or foiled twisted pair (typically S/FTP or F/UTP cable shielding ), UTP cable is not surrounded by any shielding. UTP is the primary wire type for telephone usage and is very common for computer networking . The earliest telephones used telegraph lines which were single-wire earth return circuits. In

1537-471: The cable. UTP is also the most common cable used in computer networking . Modern Ethernet , the most common data networking standard, can use UTP cables, with increasing data rates requiring higher specification variants of the UTP cable. Twisted-pair cabling is often used in data networks for short and medium-length connections because of its relatively lower costs compared to optical fibre and coaxial cable . As UTP cable bandwidth has improved to match

1590-416: The common use of polyethylene and other plastics for insulation, telephone twisted pair cable was insulated with waxed paper or cotton with a wax coating applied to the copper. The overall sheath of this type of cable was usually lead. This style of cable came into use in the late 19th century shortly after the invention of the telephone. The cable termination in termination boxes were sealed with molten wax or

1643-517: The electrical requirements of high-speed LAN protocols. Twisted pair Twisted pair cabling is a type of communications cable in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility . Compared to a single conductor or an untwisted balanced pair , a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighbouring pairs and improves rejection of external electromagnetic interference . It

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1696-552: The frame may carry live broadcast signals, it may be considered part of the airchain. In data communication, a building distribution frame (BDF) houses data switches, etc. Distribution frames for specific types of signals often have specific initialisms : Distribution frames may grow to extremely large sizes. In major installations, audio distribution frames can have as many as 10,000 incoming and outgoing separate copper wires ( balanced audio signals require two wires plus earth ground for each signal). Telephone signals do not use

1749-428: The interfering source remains uniform, or nearly so, over the distance of a single twist, the induced noise will remain common-mode. The twist rate (also called pitch of the twist, usually defined in twists per metre ) makes up part of the specification for a given type of cable. When nearby pairs have equal twist rates, the same conductors of the different pairs may repeatedly lie next to each other, partially undoing

1802-425: The length of the cable. Pioneered by Belden , it is intended to help assure configuration consistency during and after installation. One key benefit is that the noise immunity performance of the cable can be protected despite potentially rough handling. The enhanced performance may be unnecessary and bonding reduces the flexibility of the cable and makes it prone to failure where it is flexed. A twisted ribbon cable

1855-407: The noise source is close to the signal wires; the closer wire will couple with the noise more strongly and the receiver will be unable to eliminate it. This problem is especially apparent in telecommunication cables where pairs in the same cable lie next to each other for many miles. Twisting the pairs counters this effect as on each half twist the wire nearest to the noise source is exchanged. Provided

1908-447: The plug. Connected pins on the plug and jack have the same number. Both T568A and T568B configurations wire the pins "straight through," i.e., pins 1 through 8 on one end are connected to pins 1 through 8 on the other end. Also, the same sets of pins connect to the opposite ends that are paired in both configurations: pins 1 and 2 form a pair, as do 3 and 6, 4 and 5, and 7 and 8. One can use cables wired according to either configuration in

1961-903: The popularization of fiber optic cables also drove significant change in the standards. These changes were first released in a revision C in 2009 which has subsequently been replaced by revision D (named ANSI/TIA-568-D ). ANSI/TIA-568 defines structured cabling system standards for commercial buildings, and between buildings in campus environments. The bulk of the standards define cabling types, distances, connectors, cable system architectures, cable termination standards and performance characteristics, cable installation requirements and methods of testing installed cable. The main standard, ANSI/TIA-568.0-D defines general requirements, while ANSI/TIA-568-C.2 focuses on components of balanced twisted-pair cable systems. ANSI/TIA-568.3-D addresses components of fiber optic cable systems, and ANSI/TIA-568-C.4, addressed coaxial cabling components. The intent of these standards

2014-552: The purposes of twisting wires in pairs. In Digital Signal 1 (T1) service, pairs 1 and 3 (T568A) are used, and the USOC-8 jack is wired according to the RJ-48 C specification. The termination jack is often wired according to the RJ-48 X specification, providing a transmit-to-receive loopback when the plug is withdrawn. Vendor cables are often wired with tip and ring reversed—i.e., pins 1 and 2 or 4 and 5 reversed. This does not affect

2067-487: The quality of the T1 signal, which is fully differential and uses the alternate mark inversion (AMI) signaling scheme. Because pair 1 connects to the center pins (4 and 5) of the 8P8C connector in both T568A and T568B, both standards are compatible with the first line of RJ11, RJ14, RJ25 , and RJ61 connectors that all have the first pair in the center pins of these connectors. If the second line of an RJ14, RJ25, or RJ61 plug

2120-544: The same installation without significant problems if the connections are the same on both ends. A cable terminated according to T568A on one end and T568B on the other is a crossover cable when used with the earlier twisted-pair Ethernet standards that use only two of the pairs because the pairs used happen to be pairs 2 and 3, the same pairs on which T568A and T568B differ. Crossover cables are occasionally needed for 10BASE-T and 100BASE-TX Ethernet. Swapping two wires between different pairs causes crosstalk , defeating one of

2173-600: The shield. The shield also provides a conduction path by which induced currents can be circulated and returned to the source via a ground reference connection. Such shielding can be applied to individual pairs or to a collection of pairs. Shielding may be foil or braided wire. When shielding is applied to a collection of pairs, it is usually referred to as screening, but usage among vendors and authors in applying such words as screening , shielding , and STP (shielded twisted pair) can be subject to variability. ISO/IEC 11801 :2002 (Annex E) attempts to internationally standardize

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2226-436: The shielding is conductive, it may also serve as a path to ground. A foil-shielded, twisted pair cable may have an integrally incorporated grounding wire called a drain wire which makes electrical contact with the shield. The purpose of the drain wire is for easy connection to terminals which are usually designed for connection of round wires. Common shield construction types include: An early example of shielded twisted-pair

2279-712: The standardization process can reasonably be said to have provided at least a nine-year lifespan for premises cabling, and arguably a longer one. All these documents accompany related standards that define commercial pathways and spaces (TIA-569-C-1, February 2013), residential cabling (ANSI/TIA-570-C, August 2012), administration standards (ANSI/TIA-606-B, December 2015), grounding and bonding (TIA-607-C, November 2015), and outside plant cabling (TIA-758-B, April 2012). The standard defines categories of shielded and unshielded twisted pair cable systems, with different levels of performance in signal bandwidth, insertion loss, and cross-talk. Generally increasing category numbers correspond with

2332-411: The total package covered in a polyethylene jacket. For urban outdoor telephone cables containing hundreds or thousands of pairs, the cable is divided into small but identical bundles. Each bundle consists of twisted pairs that have different twist rates, as pairs having the same twist rate within the cable can still experience some degree of crosstalk . The bundles are in turn twisted together to make up

2385-465: The various shielding designations for twisted pair (TP) cables using an explicit two-part abbreviation in the form of x/xTP , where the first x indicates the shielding for the overall cable and the second x indicates the shielding for individual pairs or quads, where each x can be: Shielded Cat 5e , Cat 6/6A , and Cat 8/8.1 cables typically have F/UTP construction, while shielded Cat 7/7 A and Cat 8.2 cables use S/FTP construction. Because

2438-406: The wire pairs in the cable, in order, are blue (for pair 1), orange, green, and brown (for pair 4). Each pair consists of one conductor of solid color and a second conductor, which is white with a stripe of the other color. The difference between the T568A and T568B pinouts is that the orange and green wire pairs are exchanged. See modular connector for numbering of the pins. The pin numbering on

2491-407: The work area, equipment is connected by patch cords to horizontal cabling terminated at jack points. TIA/EIA-568 also defines characteristics and cabling requirements for entrance facilities , equipment rooms and telecommunications rooms. Perhaps the most comprehensive known and most discussed feature of ANSI/TIA-568 is the definition of the pin-to-pair assignments, or pinout , between the pins in

2544-605: Was IBM STP-A, which is a two-pair 150 ohm S/FTP cable defined in 1985 by the IBM Cabling System specifications, and used with Token Ring or FDDI networks . Before digital communication and Ethernet became widespread there was no international standard for telephone cable. Standards were set at a national level. For instance, in the UK the General Post Office specified CW1293 and CW1308 cables. CW1308

2597-464: Was a similar specification to the earlier CW1293 but with an improved colour code. CW1293 used mostly solid colours on the cores making it difficult to identify the pair it was twisted with without stripping back a large amount of sheath. To solve this problem. CW1308 has narrow rings of the paired colour printed over the base colour. Both cables are a similar standard to category 3 cable. Cables with categories 3 through 7 have 4 twisted pairs. Prior to

2650-572: Was developed through the efforts of more than 60 contributing organizations including manufacturers, end-users, and consultants. Work on the standard began with the Electronic Industries Alliance (EIA), to define standards for telecommunications cabling systems. EIA agreed to develop a set of standards, and formed the TR-42 committee, with nine subcommittees to perform the work. The work continues to be maintained by TR-42 within

2703-443: Was formerly common practice on telecommunication lines. The added inductors are known as load coils and reduce attenuation for voiceband frequencies but increase it on higher frequencies. Load coils reduce distortion in voiceband on very long lines. In this context a line without load coils is referred to as an unloaded line. A bonded twisted pair is a construction variant in which the two wires of each pair are bonded together for

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2756-486: Was invented by Alexander Graham Bell in 1881. By 1900, the entire American telephone network was either twisted pair or open wire with transposition to guard against interference. Today, most of the millions of kilometres of twisted pairs in the world are outdoor landlines, owned and maintained by telephone companies, used for voice service. Unshielded twisted pair (UTP) cables are found in many Ethernet networks and telephone systems. For indoor telephone applications, UTP

2809-439: Was invented by Alexander Graham Bell . For additional noise immunity, twisted-pair cabling may be shielded . Cable with shielding is known as shielded twisted pair ( STP ) and without as unshielded twisted pair ( UTP ). A twisted pair can be used as a balanced line , which as part of a balanced circuit can greatly reduce the effect of noise currents induced on the line by coupling of electric or magnetic fields. The idea

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