TIA/EIA Structured Cabling Standards
In the mid-1980s, the TIA (Telecommunications Industry Association) and the EIA
(Electronic Industries Association) began developing methods for cabling buildings,
with the intent of developing a uniform wiring system that would support multiple
vendor products and environments. In 1991, the TIA/EIA released the TIA/EIA 568
Commercial Building Telecommunication Cabling standard. Note that the ISO/IEC11801 Generic Customer Premises Cabling standard is an international cabling
standard that is based on the ANSI/TIA/EIA-568 cabling standard.
The TIA/EIA structured cabling standards define how to design, build, and manage a
cabling system that is structured, meaning that the system is designed in blocks that
have very specific performance characteristics. The blocks are integrated in a
hierarchical manner to create a unified communication system. For example,
workgroup LANs represent a block with lower-performance requirements than the
backbone network block, which requires high-performance fiber-optic cable in most
cases. The standard defines the use of fiber-optic cable (single and multimode), STP
(shielded twisted pair) cable, and UTP (unshielded twisted pair) cable.
The initial TIA/EIA 568 document was followed by several updates and addendums
as outlined below. A major standard update was released in 2000 that incorporates
previous changes.
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TIA/EIA-568-A-1995 (Commercial Building Telecommunications
Wiring Standards) Defines a standard for building cable system for
commercial buildings that support data networks, voice, and video. It also
defines the technical and performance criteria for cabling.
TIA/EIA-568-A updates (1998-1999) The TIA/EIA-568 was updated
several times through this time period. Update A1 outlined propagation delay
and delay skew parameters. Update A2 specified miscellaneous changes.
Update A3 specified requirements for bundled and hybrid cables. UPDATES A4
defined NEXT and return loss requirements for patch cables. Finally, update
A5 defined performance requirements for Enhanced Category 5 (Category
5E).
TIA 568-B.1-2000 (Commercial Building Telecommunications Wiring
Standard) The year 2000 update packages all the previous addendums and
service updates into a new release and, most important, specifies that
Category 5E cable is the preferred cable type that can provide minimum
acceptable performance levels. Several addendums were also released that
specify technical information for 100-ohm twisted-pair cable, shielded
twisted-pair cable, and optical fiber cable.
TIA/EIA-569-A-1995 (Commercial Building Standard for
Telecommunications Pathways and Spaces) This standard defines how
to build the pathways and spaces for telecommunication media.
TIA 570-A-1998 (Residential and Light Commercial
Telecommunications Wiring Standard) This standard specifies residential
cabling.
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TIA/EIA-606-1994 (Building Infrastructure Administration
Standard) This standard defines the design guidelines for managing a
telecommunications infrastructure.
TIA/EIA-607-1995 (Grounding and Bonding Requirements) This
standard defines grounding and bonding requirements for telecommunications
cabling and equipment.
The current trend is to evolve the standards to support high-speed networking such
as Gigabit Ethernet and define advanced cable types and connectors such as fourpair Category 6 and Category 7 cable. Category 6 is rated for channel performance
up to 200 MHz, while Category 7 is rated up to 600 MHz.
The remainder of this section discusses the TIA/EIA-568 standard in general, rather
than any specific release. According to TIA/EIA 568 documents, the wiring standard
is designed to provide the following features and functions:
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A generic telecommunication wiring system for commercial buildings
Defined media, topology, termination and connection points, and
administration
Support for multiple products, multivendor environments
Direction for future design of telecommunication products for commercial
enterprises
The ability to plan and install the telecommunication wiring for a commercial
building without any prior knowledge of the products that will use the wiring
The layout of a TIA/EIA 568-A structured cable system is illustrated in Figure T-8.
The hierarchical structure is apparent in the multiple floor office building. A vertical
backbone cable runs from the central hub/switch in the main equipment room to a
hub/switch in the telecommunication closet on each floor. Work areas are then
individually cabled to the equipment in the telecommunication closet.
The TIA standard defines the parameters for each part of the cabling system, which
includes work area wiring, horizontal wiring, telecommunication closets, equipment
rooms and cross- connects, backbone (vertical) wiring, and entrance facilities. Each
of these is described next.
Work Area
The work area wiring subsystem consists of the communication outlets (wall boxes
and faceplates), wiring, and connectors needed to connect the work area equipment
(computers, printers, and so on) via the horizontal wiring subsystem to the
telecommunication closet. The standard requires that two outlets be provided at each
wall plate-one for voice and one for data.
Horizontal Wiring
The horizontal wiring system runs from each workstation outlet to the
telecommunication closet. The maximum horizontal distance from the
telecommunication closet to the communication outlets is 90 meters (295 feet)
independent of media type. An additional 6 meters (20 feet) is allowed for patch
cables at the telecommunication closet and at the workstation, but the combined
length cannot exceed 10 meters (33 feet). As mentioned earlier, the work area must
provide two outlets. The horizontal cable should be four-pair 100-ohm UTP cable (the
latest standards specify Category 5E), two-fiber 62.5/125-mm fiber-optic cable, or
multimode 50/125-mm multimode fiber-optic cable. Coaxial cable is no longer
recommended.
Telecommunication Closet
The telecommunication closet contains the connection equipment for workstations in
the immediate area and a cross-connection to an equipment room. The
telecommunication closet is a general facility that can provide horizontal wiring
connections, as well as entrance facility connections. There is no limit on the number
of telecommunication closets allowed. Some floors in multistory office buildings may
have multiple telecommunication closets, depending on the floor plan. These may be
connected to an equipment room on the same floor.
Equipment Rooms and Main Cross-Connects
An equipment room provides a termination point for backbone cabling that is
connected to one or more telecommunication closets. It may also be the main crossconnection point for the entire facility. In a campus environment, each building may
have its own equipment room, to which telecommunication closet equipment is
connected, and the equipment in this room may then be connected to a central
campus facility that provides the main cross-connect for the entire campus.
Backbone Wiring
The backbone wiring runs up through the floors of the building (risers) or across a
campus and provides the interconnection for equipment rooms and
telecommunication closets. The distance limitations of this cabling depend on the
type of cable and facilities it connects. Refer to Figure T-11 and the following table.
Note that UTP is limited to 90 meters.
Cable Type
MC to ER
Multimode fiber
2,000m (6,560 ft)
Single-mode fiber
3,000m (9,840 ft)
UTP (<5MHz)
800m (2,624 ft)
Entrance Facilities
The entrance facility contains the telecommunication service entrance to the
building. This facility may also contain campus-wide backbone connections. It also
contains the network demarcation point, which is the interconnection to the local
exchange carrier's telecommunication facilities. The demarcation point is typically 12
inches from where the carrier's facilities enter the building, but the carrier may
designate otherwise.