Link and Channel TestingTwo methods are used when testing: the channel test and the link test.. The channel test measures all of the cable and patch cords, including the line cord from t
Trang 1Link and Channel Testing
Two methods are used when testing: the channel test and the link test The channel test
goes truly end-to-end from the workstation or telephone to the device in the
telecom-munications room (TR) The channel test measures all of the cable and patch cords,
including the line cord from the jack to the user equipment and the patch cord from
the patch panel to the communications equipment Alternatively, the link test tests
only the cable from the wall back to the patch panel There are two types of link tests,
the basic link test and the permanent link test The basic link test allows no
connec-tors, but the point of measurement starts near the field tester and ends near the field
tester remote unit at the other end of the link The permanent link test excludes the
cable portions of the field test units, but includes the mated connection where the cable
is connected to the adapter cable at each end (see Figure A-48)
Figure A-48 Permanent Link Test
The permanent link test also allows for a consolidation point, which is desirable for
open-office cabling installations and is therefore more practical
The only accepted test is the permanent link test The channel test officially has been
eliminated by TIA/EIA-568-B.1
Certification Tips
How test results are interpreted is just as important as detecting problems The best
way to learn how to interpret test results is to use test equipment on known good wires
and circuits This will give the installer a knowledge base of how to properly use test
equipment and how the test results should appear when the circuits are functioning
properly
To gain experience with troubleshooting and problem identification, create cables with
specific problems Observe how testers react to these problems Practice identifying
these problems based on the results of testers by randomly choosing cables It will be
worth spending the time now to be efficient because the installer will want to be able
to quickly determine what is wrong and fix it
Consolidation Point
Trang 2950 Appendix A: Structured Cabling
Professional Certification Documentation
Many cable certification tools include the capability to export results in a database for-mat This can be used in a personal computer to produce high-quality documents (see Figure A-49)
Figure A-49 Cable Certification Documentation
Installation software, generally provided with sophisticated certification testers, enable the contractor to present the test result to the customer in an orderly and presentable manner The software eliminates the need for entering the results by hand into a spreadsheet Software packages store test results as either pass or fail When deficiencies are found and corrected, items are retested and presented to the customer Customers generally want both an electronic copy of the test results, as well as a paper copy Documentation must be accessible to be useful Electronic delivery ensures that the results are always available to those who might need them In addition, a paper set of both the as-built documents and the certification results should be provided to the cus-tomer, as well as retained in the installer’s permanent records
When a cabling system undergoes certification testing, the test results should be collected
to create the as-built documents Certification documentation can become important
to an installer if there is a question about the quality or accuracy of the wiring job It shows that on a certain date, the wires existed in a particular order and could carry signals at a particular quality Changes over time that affect the cable’s capability to move signals can be illustrated by comparing current tests to previous ones
Because of unexpected obstacles, change orders, and last-minute equipment upgrades, there is a possibility that the network wiring system documentation that was used to construct a facility wiring system is not representative of the system that actually was constructed Anytime someone is asked to make a modification to the wiring system, it
Worst Pair 36-45 36-45 36-45 12-45 ACR (dB) 18.2 71.7 15.2 16.5 Freq (MHz) 214.5 3.5 250.0 248.0 Limit (dB) 8.2 61.8 4.8 4.8 Worst Pair 45 36 45 36 PSACR (dB) 16.0 13.2 13.0 13.2 Freq (MHz) 250.0 240.0 248.5 250.0 Limit (dB) 5.7 2.0 2.2 2.0
Worst Pair 45 12 45 45
RL (dB) 17.4 26.0 17.4 20.2 Freq (MHz) 244.0 7.3 244.0 174.0 Limit (dB) 10.1 21.0 10.1 11.5 Compliant Network Standards:
10BASE-T 100BASE-TX 100BASE-T4 1000BASE-T ATM-25 ATM-51 ATM-155 100VG-AnyLan TR-4 TR-16 Active TR-16 Passive
ACR
Frequency (MHz)
dB 100 80 60 40 20 0
350
ACR & Remote
Frequency (MHz)
dB 100 80 60 40 20 0
350
RL
Frequency (MHz)
dB 60 50 40 30 20 10
350 1
RL & Remote
Frequency (MHz)
dB 60 50 40 30 20 10
350 1
Trang 3is imperative to know what really is going on in the system Otherwise, making changes
could have unpredictable effects As-built documents can help avoid this kind of trouble
Always create change documents before actually making any changes
Cutting Over
Cutting over is the term used when transferring existing services to a new cable system
or when installing new equipment on a newly installed cable system
Cutover Guidelines
Good cutovers require careful planning, organization, and meticulous attention to
detail When cutting over, follow these guidelines to ensure success:
■ Keep detailed records of the installation Such records will verify that all cables
have been installed and that they were installed in the correct location
■ Test every cable that is installed
■ Develop accurate cut sheets, charts of circuits and the cable or circuit on which
they operate The installation supervisor normally develops cut sheets with infor-mation received by the customer
■ Schedule the cutover when it inconveniences the customer the least Because
cutovers usually require taking some systems offline, they often are scheduled late at night or on weekends
Removing Abandoned Cable
When the National Electrical Code, edition 2002, is used, all abandoned cables must
be removed when certain criteria defined within the code is met Currently, this is a
decision that is made by the customer and the cable installation contractor regarding
whether the cost involved in removing cables is justified The customer and the
con-tractor must be sure to adhere to local code Always check with the local authority and
discuss the details with the customer before beginning the retrofit
Before removing any abandoned cable, verify that no live circuits are on the cable This
is accomplished by checking with the customer and then verifying with either a
multi-meter or a telephone test set Care must be taken not to damage ceiling tiles or dropped
ceiling-support members when removing abandoned cable
Trang 4952 Appendix A: Structured Cabling
The Cabling Business
The cabling business requires its share of attention, as does the business side of any other enterprise Before cables can be installed, there must be a bid Before there can be
a bid, there must be a request for a proposal and walkthroughs to determine the pre-cise scope of the work Documentation both to describe the project and to show how it was actually built might be required Licenses might be required to perform the work,
as well as perhaps union membership All projects must be performed in a timely manner, with minimal waste of time or materials This is usually a job for project planning, using program-management applications
Topics or particular importance in the cabling business filed are these:
■ Site survey
■ Labor situations
■ Contract revision and signing
■ Project planning
■ Final documentation
As with most jobs, a cable installer’s appearance and demeanor can have an affect on how he is perceived by customers, bosses, and fellow employees The choices that a cable installer makes on the job can affect whether he is promoted or even terminated
As an employee of a company, the cable installer represents that company on a job His appearance and conduct reflects on the company Therefore, you should always maintain a professional appearance and demeanor
When working on a job, follow these guidelines:
■ Respect the job site Be careful not to cause damage or discard trash Clean up all messes immediately if they affect another person, or clean them up at the end of the day
■ Come to the job site wearing clean, neat work clothes
■ Show up to a job at the agreed upon time Punctuality is important
■ Be considerate of noise If working on a retrofit project where business still is being conducted, avoid playing music, whistling, singing, or shouting
■ Treat customers, building occupants, co-workers, and bosses with respect
Site Survey
The site survey, or project walk-through, is one of the most important events before preparing a cost estimate for the project It gives the contractor the opportunity to see any issues that might impact the installation Drawings and specifications supplied by the customer might not indicate problems or complications
Trang 5It is advisable to create a sketch of the project while conducting the walk-through The
sketch will be useful for identifying problem areas when it becomes time to actually
perform the estimate
A number of key questions should be asked on a site survey:
■ Are there plenum ceiling areas?
■ Is there a staging and storage area for materials?
■ Are special work hours required?
■ Are there special safety requirements? (This is particularly relevant in factory
environments.)
■ Which walls are firewalls?
■ Is there asbestos in the building?
■ Will the customer supply spare ceiling tiles in the event of breakage?
■ Are there special labor issues to be considered?
Requirements Documents
determining the length of cable runs (see Figure A-50) Blueprints also should show
service outlet locations and TRs They will not always show available paths or routing
information Routing information generally is gathered through the site survey Most
structured wiring systems define a minimum of two four-pair cables per location, while
many customers specify more This information should be duplicated in the
specifica-tions for the project
Figure A-50 Typical Building Blueprints
CER B1 Serving Zone B1
Legacy Thicknet Serving Zone CER D1 Serving Zone D1
Serving Zone A1 Building Demarc CER A1
Serving Zone C1 CER C1
Trang 6954 Appendix A: Structured Cabling
Counting outlet locations and measuring cable distances on a blueprint are referred to
as doing take-offs Doing take-offs requires a great degree of accuracy because this gives the material requirements for the bid Automated measuring devices are available
to help minimize the chance for error
Installation Icons and Symbols
Standard icons and symbols are used on blueprints and schematics to identify cable runs, different types of raceways, and information about outlets and jacks (see Figure A-51) They provide a uniform method of graphically identifying requirements on a blueprint
Figure A-51 Cabling Installation Icons
Drawing Types
Construction blueprints follow a standardized format Drawings are grouped accord-ing to category Drawaccord-ings are labeled with a prefix that associates the drawaccord-ings with the category For example, all drawings that have to do with the electrical system are
grouped together and have the prefix E for electrical Architectural sections begin with A, plumbing begins with P, and so on Telephone and data usually are grouped together and are represented on the T drawings, as follows:
■ T0—Campus or site plans: exterior pathways and interbuilding backbones
■ T1—Layout of complete building per floor: serving zone boundaries, backbone,
and horizontal pathways
Wall Outlet
Floor Outlet Ceiling Drop Pole Coiling Outlet Two Wall Outlets Home Run to
TR Outlet Boxes Tied Together Wall Outlet with Conduit Stub Up
Conduit in Slab
Header Duct Access Unit Duplex Receptical Outlet
Wall Switch Incandesent Fixture
Continuous Row Flourescent Fixture Flourescent Fixture Ladder Rack
DVC
Trang 7■ T2—Serving zone drawings: drop locations and cable labels
■ T3—Communication equipment rooms: plan views of racks and elevations of walls
■ T4—Typical detail drawings: faceplate labeling, fire-stops, and safety features
■ T5—Schedules (cabling and equipment spreadsheets) for cutovers
There may be additional drawings, such as furniture plans Furniture plans are found
in either the A drawings or in a miscellaneous category
Drawings that the estimator will require include the following:
■ A site plan, to get an overview of the project
■ Floor plans
■ T drawings (telephone)
■ E drawings (electrical), for reference
■ Furniture plans to help determine outlet placement
■ A drawings (architectural), for assistance with available pathways
Design documents provide a narrative describing the project This might include a
description of the functionality of the cabling system to be installed It might include a
statement such as “the system must support 1000BASE-T (Gigabit Ethernet on twisted
pair).”
Design documents also usually include trade jargon and acronyms unique to an
indus-try or the system to be installed The estimator should have a good understanding of
all terms in the design document Glossaries of terms and acronyms are available The
Building Industry Consultants Service International (BICSI) website includes a glossary
of such terms and acronyms
Design documents specify the requirements of the system and the types of materials to
be used Information on the number of cables required per information outlet or jack
is supplied in the design document Design documents also describe testing
specifica-tions and labeling specificaspecifica-tions and formats
Schematic Diagrams
Schematic drawings are not to scale They are used to depict connectivity—that is, the
way things are connected A typical schematic shows the main TR or main cross-connect
(MC) and the intermediate cross-connect (IC) It shows the type and size of cables
between these points It generally does not detail the actual terminations at these
locations, and it does not show individual cable runs to information outlets or jacks
It shows cable runs to specific pieces of equipment, such as servers or other major
components that are used in the project
Trang 8956 Appendix A: Structured Cabling
Labor Situations
Every cable-installation company must deal with labor issues Some of these issues can cause problems with unions The installation company must be aware of the rules and regulations that cover things such as unions and licensing
Unions
Some projects require the use of union labor Unions are organizations that represent workers Although the use of union labor is more common on new-construction projects,
it is not limited to new construction The use of union labor might be part of the con-tract If the customer clearly states that union labor must be used, the contractor must use union labor
Other labor situations dictate the job classification and the work that is allowed In a union environment, supervisors normally are not allowed to perform installation work
of any kind Likewise, cable installers are not allowed to install raceway Sometimes, cable installers can install raceway up to a certain size or a certain length; an electrician must install anything beyond that These rules are defined by a union agreement and often are determined by an agreement between unions of different trades
Contractor’s Licenses
Not all countries or even all states require contractors to be licensed In the United States, contractor license rules vary from state to state Some states require the con-tractor show that he is licensed by displaying the license number on all advertising, business cards, and letterhead Contractors that operate without a license in a place where a license is required can be fined for doing so They also can lose certain rights, such as the right to file a lien if the customer does not pay for services rendered The requirements for a contractor to become licensed include technical knowledge, business knowledge, and knowledge of the labor laws of the state It is the contractor’s responsibility to know whether he must be licensed in a particular state or country
Contract Revision and Signing
When all the negotiations are complete, the contract must be revised to reflect the changes that both parties agreed to Both parties still must review the contract in detail Contract negotiation is a verbal event in which both parties must ensure that their intentions accurately are represented in the written document Changes to the contract that occur as the project progresses often are addressed in amendments to the contract Amendments are agreed to by both parties and signed by both parties
Trang 9Responsible and authorized parties from the customer’s organization and the contractor’s
organization must sign the contract before it is a valid agreement When both parties
have signed the contract, the commitment is made No materials should be ordered
and no work should commence before the contract is signed
Common documents such as change orders can be created in advance as a template
and simply filled in with the correct information These templates can be taken along
to the project site and filled out during the initial meeting or at the different walkthroughs
Any changes to a project after it has been started should be made by written change
order only No changes to the original plan should be started by verbal instructions
only; the contractor should have change order forms The project manager should
have these forms on the job site Change orders that result in extra work should include
the cost of the extra labor and materials, whenever possible If this is not possible, the
change order should include a statement that the customer agrees to pay for extra work
Project Planning
The planning phase of a project actually begins after a project is awarded and before
a formal contract is signed Bidding and estimating information is assembled, special
requirements are noted, resource allocations are made, and a final review of the RFP
takes place to make sure that all the components will be addressed
The following are all steps that should be taken in this planning phase:
Step 1 The first step in planning a cabling project is selecting the project
manager or supervisor
Step 2 Crews must be selected based on the size of the project, number of hours
for completion, skills required, and time allowed for completion
Step 3 Subcontractors must be identified and scheduled
Step 4 Material delivery schedules must be made
Step 5 Provisions for waste disposal must be made
Suppliers
The estimator normally selects suppliers on the basis of cost, delivery, and service The
estimator uses the following questions to determine the total cost of material:
■ Does the supplier’s pricing include shipping?
■ Does the supplier have a history of delivering goods at the time promised?
■ What is the supplier’s policy on returned goods?
■ Can the supplier provide cut sheets and engineering drawings in a timely manner?
■ Can the supplier provide technical advice and support?
Trang 10958 Appendix A: Structured Cabling
Ordering Materials
After the contract is signed, written purchase orders should be used to order materials from suppliers Purchase orders should include the description of the material, the manufacturer’s part number, quantity, price, delivery date, and delivery location Generally, the lowest-cost supplier that can provide the specified cable and equipment
in the quantities that are required is the supplier to select Shipping costs must be con-sidered when evaluating the lowest cost Supplier pricing should include a guarantee that the pricing will be firm for a specified period of time Generally, suppliers guarantee pricing for at least 30 days The supervisor or lead contractor must take care that no unapproved substitutions are made in an effort to reduce cost
Final Documentation
Providing as-built drawings to the customer is one of the most important parts of completing a cabling project The drawings show cable routes, termination points, and cable types as they actually were installed In most cases, some cables are not installed as originally planned because obstructions or problems were encountered Typical changes include adding or deleting cable runs or outlets, or routing cables by
a different path The as-built drawings give the customer a diagram of the work that actually was performed (see Figure A-52)
Figure A-52 As-Built Drawings
Building A West
1cm = 10ft 1in = 10m
Legend Notes
Wall outlets receive 2 four pair cables Ceiling outlets receive one four pair cable Floor outlets receive one four pair cable
Special Systems Floor Plan
Sunset Key Map
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