Premise wiring info, backbone wiring, horizontal wiring, work area wiring, the telecommunications closet, equipment room wiring, cabling administration, media for backbone cabling, media for horizontal cabling, media for work area cabling

Premise Wiring

Quote Requests Buy Online

Some experts estimate that 70% of network failures are primarily caused by cable-related problems, so the cables are really important. Below you will find general information about premise wiring. Please call us or request a quote for any cabling project you have. We will be happy to help you find the best solution within your budget.

The TIA/EIA-568 Standard

Developed jointly by the Telecommunications Industries Association and the Electronic Industries Association, TIA/EIA-568 specifies complete electrical and physical guidelines for industry-standard premise wiring systems. As specified by the TIA/EIA, a fully functional premise wiring system is the result of multiple subsystems working together as a single network.

Backbone Wiring encompasses all wiring between telecommunications closets, equipment rooms, and entrance facilities, including all cables, mechanical cable terminations, and intermediate and main cross-connects. Backbone wiring runs between telecommunications closets, equipment rooms and entrance facilities on the same floor, from floor to floor, and even between buildings.

Horizontal Wiring encompasses all cable from a work-area wallplate or network connection to the telecommunications closet. The outlets, cable, and cross-connects in the closet are all part of the horizontal wiring, which gets its name because the cable typically runs horizontally above ceilings or along the floor.

The work area includes all cable components between a horizontal-wiring wallplate or LAN outlet and end-user telecomm devices, such as telephones, data terminals, computers, modems, etc. Work-area components can include connectors, cables, adapters, terminators, and more.

The telecommunications (or wiring) closet is a room or cabinet that holds distribution frames, cross-connects, and other hardware needed to connect horizontal wiring to backbone wiring. Each building must have at least one wiring closet.

An equipment room houses building telecommunications systems such as PBXs, servers, and the mechanical terminations of the telecomm wiring system. Considered different than a wiring closet because of the complexity of the components it contains, an equipment room nonetheless may take the place of a building's wiring closet or it may be a separate entity.

Unlike the other five components of premise wiring systems, cabling administration isn't a place. It's a thing—a process that includes all aspects of premise wiring related to documenting and managing the system, testing the system, as well as the architectural plans for the system.

Recommended media for backbone cabling

Unshielded twisted-pair (UTP) cable - Choose 4-pair, 100-ohm, solid-conductor UTP cable for short- to medium-distance backbone cable in voice and data networks. Solid-conductor cables are intended for stable runs and shouldn't be subject to repeated flexing or twisting. We recommend Category 5 or the newly ratified Category 5e cable for new UTP installations to avoid expensive rewiring in the future.

Shielded twisted-pair (STP) cable - Use 2-pair, 150-ohm shielded twisted-pair cable for IBM® Token Ring networks. Type 1A STP cable is constructed of four solid copper strands wrapped in a foil shield. Type 2A STP cable includes an extra 4-pair UTP strand for phone circuits.

Fiber optic cable - Even though fiber is more expensive and requires more careful handing than other cables, it's the preferred medium for backbone cable because it offers maximum range, bandwidth, and flexibility. Compact and lightweight, fiber provides high-speed transmission over a wide bandwidth. Fiber also carries data over much farther distances than copper cable, and it's immune to EMI (electromagnetic interference). Fiber backbone cable is also far less likely to require replacement.

Coaxial cable - Although recognized by the TIA/EIA as a suitable, economical choice for backbone cable in small, Thin Ethernet (10BASE2) applications, our technical experts don't recommend 50-ohm coaxial cable for new installations.

Recommended media for horizontal cabling

UTP - Low cost, 100-ohm UTP cable supports a range of applications up to 100 MHz, making it a preferred medium for horizontal wiring. If you plan to install UTP, you must decide which type (or category) of cable you'll need. Although Category 3 or 4 cable is sufficient for most data and voice systems, Category 5 and Enhanced Category 5 (CAT5e) are highly recommended because they're certified to support any application operating up to 100 MHz or higher.
CAT5e is an excellent choice for high-speed networks. If future upgrades will require faster speeds, then installing CAT5e cable now could prevent the need for recabling in the future.

STP - This 150-ohm twisted-pair wire is usually installed as a hybrid system. Called Type 2A, hybrid cable consists of one 150-ohm STP data cable and one 100-ohm UTP Category 3 voice cable, both in the same sheath. This type of cable is generally used for Token Ring applications. But thanks to its extended bandwidth, STP can also be used for broadband video applications up to 300 MHz or for 155-Mbps ATM. TIA/EIA TSB-53 defines STP's extended specifications.

Fiber optic - Because of its increased bandwidth capabilities and the availability of work-area outlet connectibility, fiber optic cable is becoming a popular choice for horizontal connections. The TIA/EIA-568A standard recognizes two fiber types: 9/125 µm for single-mode applications and 62.5/125 µm for multimode applications. Optical signal wavelengths of 1310/1550 nm for single-mode fiber and 850/1300 nm for multimode fiber are commonly used to transmit data. For testing, an 850-nm signal is recommended for multimode; 1300-nm for single-mode.

Coaxial cable - As with backbone cable, coax isn't recommended for horizontal wiring, because the entire system could collapse if one cable is disrupted.

The work area outlet

The work area encompasses all cabling from wall outlets to end-user devices such as terminals, workstations, telephones, etc. It includes the wallplate itself, connectors, even the adapters that link cabling to the wall outlet. Work areas are designed to tolerate frequent moves, but they still need careful management. T568-A is generally used for analog voice applications requiring two lines. T568-B is more commonly used for data applications. Take care to ensure that all terminating hardware has the same Category and pinning specification as your cable, because mixing the two standards may result in crossed pairs that can bring down your network. Also be careful to follow standard procedures when installing work area outlets. For example, because of patch-cord length limits, power cables and outlet locations must be properly separated. Ensure the proper amount of twists in each cable, observe bend-radius limits, be careful not to bundle cables too tightly, etc.

The telecommunications closet

This is the service point housing all equipment associated with telecomm wiring systems. Its primary function is to serve as a termination point for the horizontal cabling system, but all transmission media terminates in this area. The closet houses cross-connects and all associated electronic equipment, backbone and horizontal cabling, and associated pathways for the cable. Most auxiliary equipment is also usually housed in this area, including security systems, key-entry systems, file servers, etc. Depending on the size of the service area, the TIA/EIA-569 standard recommends at least one telecommunications closet per floor. Specific closet sizes are also recommended, based on service-area size. This ensures sufficient space for all connecting hardware, as well as enough room for service personnel to function without causing undue system disruptions. Adequate climate controls, lighting, and power supplies are also specified. Figure 2 below shows the sample layout of a typical telecommunications closet.

The equipment room

The equipment room houses all the telecommunications systems and mechanical terminations of a premise-wiring system. It's considered separate from the telecommunications closet based on the complexity of the equipment it houses (such as PBXs, computing equipment, switches, etc.); however, all functions of an equipment room may be incorporated in a wiring closet.

Types of Conductors

Copper cables have two types of conductors: solid or stranded. Solid-conductor cables are less expensive, have better conductivity, and are easier to terminate than stranded cables.

Additionally, solid-conductor cable is ideal for both backbone and horizontal wiring. Despite these advantages, however, solid-copper cable is comparatively inflexible, and breakage is likely if it's repeatedly bent or twisted. That's why most twisted-pair cables today are made with stranded conductors—smaller-gauge wires twisted together to form a single conductor.

Stranded cable has two main advantages over solid-conductor cable: flexibility and durability. It's flexible enough to bend back and forth, so it's much easier to work with, and it's far more resistant to damage from minor scratches or nicks that may occur during cable stripping. Because the conductor wires are twisted, very little surface area is exposed to damage. In comparison, one small scratch or nick on a solid-conductor cable may be enough to ruin it, because far greater surface area is exposed to damage from cutting or crushing forces.

Shielding

Twisted-pair cable shields are metallic covers (usually copper or aluminum) that surround insulated conductors. They're constructed of foil, wire strands, or braided metal. Our techs recommend using shielded cable to protect data transmissions from external EMI, which can cause signal distortion or interference. The quality of a shield depends on its surface- transfer impedance (STI), which indicates its ability to reduce EMI—especially at high frequencies. The greater the reduction factor and the less external voltage that's picked up inside the cable, the better the shield. There are several types of cable shields.

Solid metal tubes provide proper shielding at all frequencies, which makes them the best of all. Unfortunately, their rigid construction severely limits cable flexibility, so they're used only in very special applications—industrial environments where EMI, chemicals, and cable crushing pose frequent threats.
Braided shields are made from very thin 40-32 AWG copper wire. The wire is woven into a braid with one flat ribbon of wires winding clockwise around the cable core and a second ribbon running counterclockwise. The result is a stronger, more flexible cable. This type of shield best defends against lower-frequency interference (less than 10 MHz), such as that generated by AC electricity, AM radio signals, and CB radios.

Note that a shield with a single braid can't provide 100% protection because of gaps in the weave, expecially since these gaps may expand the conductors, leaving them bent and flexed. Braided-shield cables offer 75-85% coverage and provide adequate protection for most lower-frequency applications. Cables subject to higher-frequency interference require 85-95% shielding, which can be achieved using double-braided shields that offer up to 99% protection. Other types of shielding include spiral wire shields, foil shields, and hybrid shields, all of which provide varying degrees of shielding for different kinds of applications.

Insulation and Jackets

Cable insulation serves three purposes. First, it prevents contact (or short circuits) between conductors. Second, it prevents contact between conductors and the external environment. Third, it controls heat dissipation.

Insulation in most cable consists of one or more types of plastics, which have a high resistance to the flow of electric current.

A cable jacket is the outer covering that surrounds a cable's core, shields, and insulation. Its purpose is to protect these components from mechanical damage, chemicals, moisture, and exposure to harmful environmental conditions. Most jackets are made of extrudable plastics that are heated and forced through a die to form a continuous coating around the cable. Such jackets are rated for use according to the ambient temperature of the environment in which they'll be installed. For example, cables designed for use in plenums—a building's air ducts—have jackets specially designed to tolerate high temperatures.



www.zaphound.com