Contents of this document:

150 ohm STP Telecommunications Cabling Systems
The Telecommunications Closet
Telecommunications Cabling System Adminstration

3.3.150 ohm STP CABLING SYSTEMS

Two 150 ohm STP cabling systems exist today. The initial (and unnamed) version is characterized to 20 MHz and is applicable for token ring applications up to 16 Mbps. The new version is the "Extended" 150 ohm STP, sometimes called "1A" (in reference to the extended version designator for the new Type 1 cable).

The Extended 150 ohm system is characterized to 300 MHz and is not only applicable for token ring applications up to 100 Mbps, but is also being suggested for broadband video. TSB-53 defines the extended 150 ohm STP. In TIA-568A, the extended cabling system replaces the initial version.

Extended components will be designated either by an "A" following the type designation on the cables, or an "E" or the word "EXTENDED" on the cable and connector,

Upgrading existing 150 ohm STP cabling systems to the Extended 150 ohm cabling system will not usually require replacing the cable. Contact the cable vendor to see if the existing cable meets the Extended requirements, which most existing cables exceeded. However, the connector will still have to be replaced, as the initial connector falls short of meeting requirements for Extended systems.

3.3.1. 150 ohm STP OUTLETS

The telecommunications connector to be used for terminating the 150 ohm STP cable shall be that specified by ANSI/ IEEE 802.5 for the media interface connector. This connector is hermaphroditic in design (having both male and female connector elements) so that the two identical units will mate when oriented 180 degrees with respect to each other.

The new extended version (specified in TSB-53) will be matable with the old version. It is recommended that the extended version be used in all new installations.

3.3.1.1. 150 ohm STP Outlet Installation

This connector generally is installed directly on the horizontal cable at the work area, or in the telecommunications closet.

It is suggested that a 1 to 3 foot (1/3 to 1 meter) service loop be added at both locations for adds, moves and changes. Keep in mind that this may be difficult with the cable, due to its large size.

3.3.2. 150 ohm STP CABLE 150 ohm STP cable must meet the requirements of EIA Interim Standard Omnibus Specification, NQ-EIA/IS-43, and the Detail Specifications listed in the standard.

3.3.2.1. 150 ohm STP Cable Installation

Do not exceed the manufacturer's recommendations for pulling tension.

Do not chafe or damage the outer jacket of the cable. Watch for sharp corners, screws, nails or excess flashing that may cut or chafe the jacket.

Installation in colder climates may require cables with special jackets. PVC and other jacket materials may require treatment to remain flexible in colder regions.

3.3.3.150 ohm STP TELECOMMUNICATIONS CLOSET 
CONNECTING HARDWARE

Patch panels and passive or electronic hubs are the usual crossconnect hardware. Crossconnect blocks are rarely used and are not recommended. Termination of the backbone and horizontal cables is usually to either a 150 ohm STP media interface connector, or to an IDC on the patch panel.

3.3.3.1. 150 ohm STP Crossconnect Panels Patch panels are generally one of two types: an open panel with a hole for the 150 ohm STP media interface connector to snap into, or a panel with IDCs for termination of the building cables.

In either case, follow the manufacturer's recommendations for termination.

Allow 1 to 3 feet ( 1/3 to 1 meter) of service loop for future adds, moves and changes.

For 19-inch (483-mm) rack-mounted crossconnect panel installations, allow room on the rack for possible telecommunications equipment associated with the 150 ohm STP cable.

Racks should have at least the following clearances for access and cable dressing space:

0 30 inches (762 mm) in the rear

0 36 inches (915 mm) in the front

0 14 inches (356 mm) on the side .

3.3.3.2. 150 ohm STP Hubs Passive or active hubs usually are connected via the 150 ohm STP media interface connectors and patch cords to the horizontal cabling. Backbone cables may be optical fiber or 150 ohm STP cables, and are usually connectorized and connected directly to the hub to minimize connections. In either case, follow the recommendations for 150 ohm STP patch panels.

3.3.3.4. 150 ohm STP Patch Cords and Equipment Cords

3.3.3.4.1. 150 ohm STP Patch Cords 150 ohm STP patch cords are usually purchased items and are not normally constructed in the field.

If field construction is required, follow the patch panel or hub vendor's recommendations.

Patch cord length should be limited to 23 feet (7 meters).

3.3.3.4.2. 150 ohm STP Equipment Cords The 150 ohm STP equipment cords are usually provided by the equipment vendor and are not normally constructed in the field. If field construction is required, follow the equipment vendor's recommendations.

Equipment cord length should be limited to 10 feet (3 meters).
3.5. THE TELECOMMUNICATIONS CLOSET

The Telecommunications closet (TC) is the hub of the horizontal cabling system and is the key to a well organized horizontal cabling system. Since all telecommunication transmissions to and from the work area end up in the TC, the organization of the TC is critical for future adds, moves and changes.

First, the telecommunications closet must be sufficient in size to handle the crossconnect field, the associated electronic equipment, the backbone and horizontal cables, and the pathways (conduits, etc.) for the cables-and still have enough room for a craftsperson to work, without disrupting services. The following specifications are from the Pathways Standard, TIA-569.

There should be one TC per floor, dedicated to telecommunications. If there are multiple TCs on a floor, they shall be interconnected by a minimum one trade size 3 conduit.

The TC serving an office area should be of a specific minimum size to accommodate the current and future services in the area served. These sizes may seem a little large, butthe TC needs to have enough room to allow electronic equipment to be added for voice, data, video, security, etc.
 

• Lighting shall be adequate (minimum of 50 footcandles) so that craftspersons can distinguish small lettering and work with the small wires.

• Enough electrical service and outlets to provide power for the installed electronic equipment and the craftsperson's equipment.

• Clean and free of clutter.

• Dedicated to telecommunications. The TC should not be a storage room.

• Climate controlled. Most electronic equipment designed for telecommunications closets requires a limited temperature environment. Separately controlled heating and airconditioning for the TC are almost always required.

• Secure. Businesses rely heavily on their communications systems, so access to the TC must be limited to authorized personnel. The door should be lockable.

• Located in a room other than the power distribution or mechanical equipment (heating, ventilation and air conditioning).

• Doorwidth shall be36"; it should be lockable and open outward.

3.5.1. TC CROSSCONNECT FIELDS

TC crossconnect fields must be well organized to facilitate installation and changes, as this is the key to an easy-to-administer system.

Crossconnects are usually mounted on a plywood backboard mounted to the walls of the TC. The crossconnects are usually organized first by cable type (backbone, horizontal, equipment). Then they are often collor-coded and organized into cabling system types and services due to the crossconnects required:
 

• Category 3 IDCs for voice (Category 3 100 ohm UTP)

• Category 5 lDCs or patch panels applications using Category 5 100 ohm UTP

• Extended 150 ohm STP patch panels for 100 MHz token ring

• Optical fiber patch panels for FDDl

EIA/TIA-606 suggests that TC crossconnects be organized into color coded fields. Most crossconnect devices can have colored labels or markers added for identification. Sufficient space and hardware must be provided to handle the size and weight of the backbone cables, horizontal cables, patch cords and jumper cables.

Provide a service loop at each termination for future adds, moves and changes.

For 100 ohm UTP and 150 ohm STP, only use jumper cables, patch cords, and crossconnect devices that comply with the Category or extended requirements of the cabling system. Use of lower performance components will cause performance degradation, poor quality signals, and possible data loss.

3.5.2. TC ELECTRONIC EQUIPMENT

With increasing useof communications byeach person in a commercial environment, the TCs are being equipped with more electronic equipment. Thus it is important to maintain sufficient space for cooling and heating, servicing, and cable management.

The following electronic equipment is often housed in the TC:

1) Key system 2) Small PBX

3) Multiplexer or hub

4) Security system 5) File or print servers

3.5.3. TC PATHWAYS The TC will have conduits or raceways entering the TC for backbone and horizontal cables.

3.6. CABLING SYSTEM ADMINISTRATION (COMPLIANCE WITH TIA-606)

To facilitate ongoing wiring system management and changes, wiring installations should be documented per the requirements of TIA-606. Proper wiring administration is a requirement of TIA-568A.

Wiring administration involves both the planning and documentation of each installation. Over time, changes to even the most well-laid-out installation can (and often do) degrade into an installation that is almost impossible to administer. The accumulation of 'quick fixes', leftover disconnected equipment, and nonstandard installation changes often accumulate in closets, with the result that even simple changes are more difficult and time-consuming to make.

Good administration is every bit as important as making good connections to wires. The following is a basic checklist of administration practices. If local practices have been established, these should be discussed with the building owner or manager, and adhered to carefully.

GENERAL TIPS ON WIRING ADMINISTRATION Plan for change. Allow sufficient space in closets and elsewhere to make the changes that are both inevitable and, in many cases, unforeseeable. Logically plan the points at which the system will be cross-connected suchthateach individual casecan beefficiently dealtwith, but unnecessary connections (which would degrade system performance) are not added. (This is particularly important for Category compliance.)

Avoid quick fixes. Use standard wiring practices so that all connections can be easily found and identified. Cross-connections made in ceilings, for example, are not standard, and so will inevitably be forgotten and difficult to administer.

Use a consistent plan for documenting all wiring. The plan may be simple or complex depending on the installation, but it must be complete, orderly, scrupulously maintained, and readily accessible. Finally, it should be decipherable by other installers.

Neatness is essential. All wiring should be laid out neatly and consistently. Closets should be kept clean, with adequate room to work. Do not let old equipment, leftover materials, and miscellaneous items accumulate and impede full access to wiring and equipment in use.

Assure that all connections have adequate service loop for minor changes.

Use a worksheet to document the installation and indicate the length of cable runs to each room, the location of primary and secondary outlets (identified as such and in which order they were run from the primary), the station numbers (phone numbers) of each access line (if known), and the wire color combinations for each line and the relationship between wire colors where colors have been converted at the distribution device, etcetera. Note any special circumstances, and leave a copy of the document near the distribution device for future reference.

Clearly label all station wire at each end, and clearly indicate the marking scheme on the worksheet.

Maintain the relationship of pairs and lines at the distribution device, and label the lines clearly if the distribution device does not have a clear marking scheme.

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© Copyright 1995 Leviton Manufacturing Co., Inc.

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