The standards address commercial building cabling for telecommunications products and services. As 468b wiringthe standard is at revision D, replacing the revision C, revision B, the revision A, and the initial issue ofwhich are now obsolete. These assignments are named TA and TB.
Work on the standard began with the Electronic Industries Alliance EIAto define standards for telecommunications cabling systems. EIA agreed to develop a set of standards, and 468b wiring the TR committee,  with nine subcommittees to perform the work.
The standard was updated to revision B in The demands placed upon commercial wiring systems increased dramatically 468b wiring 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 the popularization of fiber optic cables also drove significant change in the standards. These changes were first 468b wiring in a revision 468b wiring in which has subsequently been replaced by the D series. 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 intent of these standards 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 [ citation needed ]a cabling standard that mostly satisfied cabling 468b wiring for BASE-T468b wiring in Thus, the standardization process can reasonably be said to have provided at least a nine-year lifespan for premises cabling, and arguably a longer one.
The standard defines categories of unshielded twisted pair cable systems, with different levels of performance in signal bandwidth, insertion loss, and cross-talk. Generally increasing category numbers correspond with a cable system suitable for higher rates of data transmission.
Category 3 cable was suitable for 468b wiring circuits and data rates up to 16 million bits per second. Categories 1 and 2 were excluded from the standard since these categories 468b wiring only used for voice circuits, not for data.
Telecommunications design traditions utilized a similar topology. Many people refer to cross-connects by their telecommunications names: Backbone cabling is also used to interconnect entrance facilities such as telco demarcation points to the main cross-connect.
Maximum allowable backbone fibre distances vary between m and m, depending upon the cable type and use. 468b wiring cross-connects provide a point for the consolidation of all horizontal cabling, which extends in a star topology to individual work areas such as cubicles and offices. No patch cord should be longer than 5m.
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. 468b wiring the work area, equipment is connected by patch cords to horizontal cabling terminated at jackpoints.
Pinouts are important because cables do not function if the pinouts 468b wiring their two ends aren't correctly matched. The standard specifies how to connect eight-conductor ohm balanced twisted-pair cabling, such as Category 5 cableto 8P8C modular connectors often called RJ45 connectors. The standard defines two alternative pinouts: Government requires it in federal contracts.
Many organizations still use TB out of inertia. The colors of the wire pairs in the cable, in order, are: Each pair consists of one conductor of solid 468b wiring and a second conductor which is white with a stripe of the other color. The difference between the TA and TB pinouts is 468b wiring the orange and green wire pairs are exchanged.
See modular connector for numbering of the pins. Note that the only difference between TA and TB is that pairs 2 and 3 orange and green are swapped. Both configurations wire the pins "straight through", i. One can use 468b wiring wired according to either configuration in the same installation without significant problem, as long as the connections are the same on both ends.
Wiring 468b wiring ends of the same cable according to different configurations A on one end and B on the other will create a crossover cable.
Avoid swapping two lines between different pairs. This is rectified by correctly pairing the pins. The Telco 468b wiring jack is often wired to spec RJ X, which provides for a Transmit-to-Receive loopback when the plug is withdrawn.