Tài liệu Cabling Standard - TIA 758 - Customer Owned Outside Plant pptx

Aerial service wire Aerial service wire is used when extending from the distribution cable terminal to the entrance facility of a building.. Connecting Hardware Connecting hardware used

ANSI/TIA/EIA 758

Customer Owned Outside Plant

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This section is not part of the original standards documentation The purpose of this document is to provide

an easy to understand, condensed version of the original document A basic level of telecommunications is assumed For further information on terms and definitions see our Glossary of Terms section Whether you are renovating your existing cable plant or installing a new one, Cablingdb.com urges you to investigate a standards based solution This document is not meant to replace the original standards developed by the various standards bodies and we urge you to purchase the original documents through www.tiaonline.com

Pressurization of Air Core Cables

Pathways and Spaces

CABLING INFRASTRUCTURE

General

Outside Plant Definition

Outside plant is defined as those communications pathways, spaces and media which are located outside of the building walls This includes, but is not limited to the cable (copper and fiber), splices, conduit, manholes, handholes, poles and hardware related

to the attachment and support of the various forms of media

History

Prior to the divestiture of the Bell Companies, they were the ones who looked after the OSP infrastructure Now, owners have a choice of who owns, installs and manages the infrastructure One of the main issues is the lack of standardization in

requirements and installation methods It is now up to the owner to take on the burden of the decision making process of what products to use and who to get to install them

Regardless of any of the above issues, the designer has to be aware of:

The designer and installer must also be aware of the safety issues involved in working

in an OSP environment Depending on the route the installer may be working at the top of an aerial truck, or in a manhole or trench It is everyone's responsibility to ensure that proper safety precautions are taken If the route cannot be constructed without compromising the safety of those involved, the route should be altered

In a star topology one of the buildings will act as the MC and feed out the backbone cables to the various buildings In a hierarchical star there may be a building acting as

an MC, and the another group of buildings is served by a building acting as an IC.Other types of topologies that may be used are a bus or tree and branch topology, physical wired star/virtual ring and a ring A ring topology may be a single path ring,

a counter rotating redundant ring or several attached rings

Each type has its disadvantages and advantages depending on the layout of the network, media chosen and applications being run, and as well, the overall goal of the network

A single media may not satisfy all of the requirements of the owner, and therefore several types of media may be required When possible the various media should use the same pathways to keep administration and costs down In making this choice, factors to be considered include:

Bonding and Grounding

Bonding and grounding shall meet the appropriate requirements and practices of applicable authorities and codes Additionally, grounding and bonding within buildings shall conform to ANSI/TIA/EIA-607 requirements, and the National Electrical Safety Code (NESC) between buildings Failure to follow these standards and codes can result in interference, improper operation and possible harm to those operating the system

BUILDING ENTRANCE TERMINALS

General

This portion of the standard covers the requirements for building entrance terminals located at the cabling entrance to building facilities where the transition between inside and outside environments occur Building entrance terminals can be used on the outside of the building or on the inside, with the inside being the primary choice Building entrance terminals are available in sizes such as 2-pair, 4-pair, 6-pair, and multiples of 10- and 25-pair It is desirable that terminal blocks for be of the IDC type, such as 110

communications signals which carry voice and data Enhanced performance, referred

to as Broad Band Outside Plant (BBOSP) cables are intended for the distribution of signals to carry voice, high-speed data, and video Cables used shall:

• consist of 19 AWG, 22 AWG, 24 AWG, or 26 AWG thermoplastic

insulated solid copper conductors in one of the designs listed below

Cable Construction Types

OSP and BBOSP cabling is installed in aerial, duct (underground), and direct-buried applications A filled cable may be used in all applications, whereas an aircore cable is not recommended for direct buried use

Aerial (self-support and lashed)

Aerial cables come in two major classifications, self supporting and non self

supporting Self-supporting cable has a steel support messenger designed into the cable This type of cable is more sometimes referred to as "Figure 8" cable because its cross sectional view looks like an "8" OSP cable intended for aerial use without a support messenger shall be lashed to a support messenger

Direct Buried Cable

Direct buried cables are placed directly into the ground through a variety of methods such as vibratory plough or trenching These cables shall have a moisture barrier compound within the cable to prevent moisture from entering the cable should the outer sheath be penetrated.

Underground Cable

Underground cables are placed in a duct system rather that directly into the ground This helps prevent against rodent and environmental damage Cables placed in a duct system may, or may not contain a moisture barrier compound

Buried Service Wire

Buried service wire is intended for use when extending from the distribution cable to the entrance facility of a building

Aerial service wire

Aerial service wire is used when extending from the distribution cable terminal to the entrance facility of a building The maximum span length shall not exceed 60 m (200 ft)

Screened Cable (internally)

Internally screened OSP cable is for use with pulse code modulation (PCM)

transmission The screens separate cable pairs within the core into compartments (i.e., one containing the transmit pairs, and the other the receive pairs) for improved crosstalk performance over regular OSP cable

Cable Performance

Cable Type Performance Specification

Notes

* The performance requirements of the cable should be verified to ensure

they meet the overall design criteria

** The maximum length of the cable shall not be more than 213 m (700ft)

75 Ohm Coaxial Cabling

General

Coaxial cable used in backbone OSP applications is 75 ohm semi-rigid cable referred

to as trunk, feeder and distribution coaxial cable The cable is available in sizes

ranging from 10 mm to 29 mm (0.412 in to 1.160 in) in diameter In designing a coax system, the designer must understand the relationship between attenuation and the

diameter of the cable Since attenuation is lower with a larger diameter cable, the cable choice will affect the number of amplifiers in the system.

Cable Performance

Performance, mechanical and electrical requirements of coaxial cable are goverened

by the Society of Cable Television Engineers (SCTE) This group is somewhat equal to ANSI/TIA/EIA in that they specify the criteria for proper installation, testing and performance of coaxial systems and products

Mechanical and electrical requirements for 75 ohm trunk, feeder and distribution coaxial cable are found in the Society of Cable Television Engineers (SCTE) document IPS-SP-100

Connecting Hardware

Connecting hardware used with OSP Coaxial Cable is referred to as "N" type

connecting hardware, and it is designed to fit each particular cable size and type Connecting hardware includes connectors, taps and splitters The designer should verify with the cable manufacturer regarding connecting hardware that is compatible with their cable

Installation Requirements

The SCTE document "Recommended Practices for Coaxial Cable Construction and Testing, Issue 1, Section 1" provides the necessary information required for proper installation practices

This section details the requirements of fiber optic cables as they apply to an OSP

are described in more detail in their respective sections

The designer should take into consideration the following:

• route redundancy

Recognized Cables

Both multimode fibers and singlemode fibers or a combination of these fiber types are acceptable When both types of optical fibers are combined, some means of

segregating the fibers by type shall be used

Cable Performance

OSP optical fiber cable shall meet the performance requirements of ANSI/ICEA

S-83-640 and ANSI/TIA/EIA-568-B.3

Cable Construction Types

OSP optical fiber cable shall meet the physical requirements of ANSI/ICEA S-83-640 Optical fiber cables come in several designs with many construction options

Duct Cables

Duct cables are generally non-armored cables All-dielectric versions (no metallic components), which incorporate a nonmetallic central member, are available and are suitable for duct, aerial or conduit placement

Armored Cables

Armored cables have a steel armor layer added under the outer cable jacket The armor is added to improve the rodent resistance capability of a direct-buried cable, and also provides an extra layer of protection against other factors, such as rocky soil

Self-Supporting Cables

These cables are designed to be installed without the need for a pre-installed

messenger (Figure 8) These cables may or may not have metallic components in them An All Dielectric cable contains NO metallic components Self supporting cables require no lashing and may therefore be easier to install than a Figure 8 cable or a lashed cable

There may be load, length and span length limitations on these cables depending on wind and ice conditions in the geographic area the cable is being installed in The designer should check for any special hardware required

Figure 8 Cables

As with copper, these self-supporting cables incorporate a metallic messenger in a common sheath

Indoor/Outdoor Cables

Some cables can be installed in both outdoor and indoor locations This type of cable combines the attributes of an outdoor cable, ie: water blocking and UV resistance, as well as a flame resistant jacket (riser rated)suitable for indoor applications This avoids transitioning to an indoor fiber, thereby reducing costs and system losses due

to splicing and/or connectorization However, the designer should be aware that the cost of this type of fiber is higher than regular outdoor fiber, and that there is a cost point where using the two individual fiber types is more advantageous

Drop Cables

Drop cables are typically small diameter, low fiber count cables with limited

unsupported span distances They are used to feed a small number of fibers from a higher fiber count cable into a single location

Environmental Compatibility

Connecting hardware shall:

• function for continuous use within the temperature range of -40°C to 70°C

• have terminals that are resistant to corrosion from moisture, atmosphere, UV

Materials

Metal components shall:

• be resistant to or protected against general corrosion, stress corrosion cracking and pitting

• not produce significant galvanic corrosion effects on other metals in pedestal terminal closures or aerial cable terminals

Plastic parts shall:

• be compatible with metals and other materials used in the manufacture of

• resist deterioration when exposed to chemical pollutants and UV radiation

Transmission

The transmission requirements of connecting hardware used in the OSP shall comply with connecting hardware requirements of ANSI/TIA/EIA 568-B.2 It should be noted here that ANSI/TIA/EIA-B generally applies to the intra building components

However, these components are the same ones used to terminate and splice OSP cable The testing performed on OSP cable is not subject to the same testing for the permanent link or channel tests of the intra building cable, unless the OSP cable is a category rated cable which is part of the loop being tested An example may be a school having a portable classroom located within the 100 meter channel limitation that uses a category rated OSP cable to go from the main building to the portable

Terminal Block Requirements

General

Terminal blocks provide a means to connect service wire to distribution cable

Terminals are provided with a means for connecting each terminal pair to the

distribution cable, and a means for connecting the service wire to the terminal block OSP terminal blocks should be the insulation displacement contact (IDC) type, the most common being 110, just like the 110 block found in voice and data

communications Terminal blocks may be stubbed to provide conductors between the terminal block and connection point to the cable They are typically housed in an enclosure designed to protect the terminal block from moisture and sun exposure The following requirements apply to connecting hardware used as terminal blocks in OSP

Wire Compatibility, Pair Identification and Mounting

Terminal blocks shall:

• be compatible with the service wire used for an application

• have the recommended wire gauges for each block indicated by the

• shall meet electrical requirements for the smallest designated gauge conductor

for high density applications In a cross connect scenario the incoming feeder lines pairs are each terminated on a feeder cross connect block, following the appropriate color codes The distribution cable for the building is also terminated on a distribution cross connect block following the proper color codes These two blocks are then connected, pair by pair using cross connect or jumper wire

cross-connect blocks for OSP cable pairs should be the IDC type, the most common being the 110 style Cross-connect blocks are typically available in multiples of 10- or 25-pair

Cross-connect blocks in the outside environment are subject to:

• applied chemicals such as insecticides, herbicides, cleaners, and other

Wire Compatibility, Identification and Termination

Cross-connect blocks shall:

• have the recommended cable and wire gauges for each block indicated by the

• meet electrical requirements for the smallest designated gauge conductor after

• locate tip on the left and ring on the right for horizontal spacing, or tip above

• provide a means for identifying individual terminal pairs either on the block or

• have removable red markers available for attachment to a pair termination to

• have markers withstand all environmental exposure required for the block

• be designed to eliminate the possibility of electrical shorts between any two

Optical Fiber Connectors

Optical fiber connectors shall meet the requirements of ANSI/TIA/EIA-568-B.3 The two most often used connectors are the SC or 568SC duplex, or the ST connector The SC is recognized for all new installations, and the ST is grandfathered for existing applications Most fiber optic connectors are located within a building or

environmentally controlled structure

Optical Fiber Patch Cords and Cross-Connect Jumpers

In environmentally conditioned spaces, patch cords and jumpers shall meet the

requirements of ANSI/TIA/EIA-568-B.3 Additionally, if the devices are located in an environmentally unconditioned OSP spaces, patch cords and jumpers shall meet environmental test requirements of Bellcore GR-326

Optical Fiber Cable Installation Requirements

The location and protection of the optical fiber cable shall comply with 590-A All metallic components of the cable, except for metallic transmission media, shall be bonded to each other and to ground

ANSI/TIA/EIA-The minimum bend radius for OSP optical fiber cable during installation shall not be less than 20 times the cable diameter, and after installation shall not be less than 15 times the cable diameter

Optical Fiber Cable Testing

Testing of OSP optical fiber cabling shall be conducted according to 568-B.1.11

or two pairs, and generally involves restoring the integrity of the cable sheath, armor and shield

Splicing begins with the joining of the conductors with a single splice In copper splicing one of the types of splices used is the 3M Scotchlok Once all of the

conductors have been spliced they will be inserted into the splice enclosure which is selected by the location of the splice enclosure In a fiber optic splice, the fibers are joined by a mechanical or fusion splice and then inserted into a splice tray

For the purpose of this Standard, the term splice closure shall include bonding

hardware, sealing materials and the closure housing

COPPER SPLICING

General

Copper splice connectors:

• generally use IDC technology

Splicing connectors for OSP:

Due to the variety of connectors, manufacturers shall provide all of the necessary tooling required to terminate their connectors

Materials

Metal components shall:

• not produce significant galvanic corrosion effects on other metals likely to be

Insulating materials:

• shall be resistant to fungi, heat, and cable cleaning solvents

• must be compatible with metals and other materials such as conductor

Plastic materials shall:

Connector filling compounds shall:

• conform to safety and toxicology requirements at the time of manufacture

Transmission Performance Markings

If the manufacturer so desires it may mark its splicing hardware with its level of transmission performance and these markings shall be visible during installation It is suggested that the markings consist of:

· "Cat 3" for category 3 components

· "Cat 4" for category 4 components

· "Cat 5" for category 5 components

Tensile Strength

The tensile strength of a splice is the force required to pull the wire in the opposite direction of entry to the splice The pull out strength is expressed as a percentage of

the strength required to break an unspliced wire The minimum breaking strength for

a 19 AWG wire is 60% of 19 AWG wire breaking strength The breaking strength for smaller gauge splices is 75% of the wire breaking strength

Insulation Resistance

Splicing connectors that are to be used in severe service conditions shall be tested for moisture resistance This test involves immersing the moisture filled or resistant connector tap water for a period of one week The insulation resistance shall then be measured between each conductor and the water bath with 250 Vdc applied No more

corrosion, the unit shall be deemed to have failed the test It should be noted that this is a criteria for the manufacturer to follow and not the installation contractor

Salt Fog Exposure

Terminated (or spliced) filled samples shall be exposed to salt fog per ASTM B 117 for

a period of 48 hours The resistance though each splice shall not increase by more than 2 milli-ohms as a result of this exposure

OSP Twisted-Pair Cross-Connect Jumpers

Cross-connect jumper wire shall be wire of the same or higher transmission category

as the cross-connect block so as to maintain the overall performance of the system The twist shall be maintained to within 13 mm (0.5 in) of the entry into the cross-connect block

INSTALLATION REQUIREMENTS

Cable Splices for BBOSP

There are two type of splices, the butt splice (preferred) and the inline splice An line splice method can also be used if the conductors are spaced close together, i.e.,

in-no open loops The amount of untwisting of the conductor pairs shall be kept at 13

mm (0.5 in) maximum Pair splices should be staggered within the splice closure to help maximize performance

Bridge-Taps

Bridge taps may be used for low-frequency analog circuits, but are not recommended for OSP circuits or high frequency digital circuits

Binder group integrity

25-pair binder groups should not be split between termination points

Cable Bend Radius

Cable Type Minimum Bend Radius

During Installation Minimum Bending Radius After Installation

Exceeding the above bend radii may affect the performance of the system.

OSP Twisted-Pair Testing

OSP twisted pair cables are not subject to the same tests as horizontal UTP cables are The primary field test parameters for OSP twisted-pair cabling are:

• not produce significant galvanic corrosion effects on other metals used in

Non-metallic components shall:

• be compatible with metals and other materials used in the manufacture of

• resist deterioration when exposed to chemical pollutants and sunlight

COPPER TWISTED-PAIR COPPER ENCLOSURES

General

Outdoor closures may be installed:

• in maintenance and man holes

The splice enclosures are should be expected to operate at temperatures between 40ºC and 65ºC (-40ºF and 150ºF) without degradation in performance The enclosure

-is also expected to function normally if subjected to other forms of environmental factors such as ice, submersion in water and heat sources

A splice closure is used restore integrity of the cable sheath's electrical and

mechanical properties following a sheath opening to:

• close initial gaps between sheaths at splice points

Aerial Copper Closures/Terminals

• provide access to terminated cable pairs for the purpose of connecting service

Strand Mount

There are a variety of design configurations available for strand mounted enclosures, depending on the application Regardless of the overall design, strand mount devices:

• are designed for in-line installation

• may include a terminal block with a fusible-link stub cable for splicing to

• may have a separate chamber for the terminal blocks where service drop wires

• are supported by the suspension strand

• shall have all metal supporting members and all electrical shields and ground wires electrically bonded to provide a current carrying capacity at least

Some terminals designed for strand mounting may also be pole mounted, eg: at a dead end, or where a transition from aerial to buried cable is required

Special Testing

Special tests for aerial copper closures/terminals can be found in Bellcore document TR-NWT-00014

Buried Service Wire Closures

• shall be compatible with the wires

Application

Buried service wire closures:

• shall provide adequate moisture protection without the use of secondary

Splice Type Opening Provisions

Closure Housing

The closure housing shall be compatible with all materials used in the construction of cable, filling compounds, bonding and grounding devices, chemicals, and sealants which the closure would contact under normal use Secondary corrosion protection should not be required

Installation Requirements

The closure:

• minimize on-site assembly or disassembly of the closure

• should be re-enterable without destroying the housing unless it is more

• re-useable components should be immediately reusable, without factory or

• avoid using specialized tools or equipment not normally at craftsperson's

• should be usable on 254 mm to 533 mm (10 in to 21 in) sheath openings (but

• should have splice cavity diameters from 25 mm to 228 mm (1 in to 9 in) (or