Countdown to a Smooth Installation

This installation information reprinted from Greenlee Textron's "Countdown to a Smooth Installation" booklet, written by RCDD/LAN Specialist Steve Cowles, in no way enables someone to perform these types of installations. Proper training and preparation are essential before installing.

1) Check All Materials Upon Arrival, well before starting the job. This will help avoid delays due to defective, incorrect or missing products. Especially double check to make sure that the wiring configuration of the jacks matches that of the patch panels (example: both are 568B or both 568A). One of the most common problems is finding out after terminating your jacks and panels that you installed panels of one configuration and jacks of another. Even if you've only terminated 20 stations, it can be very frustrating and costly to purchase new materials and re-terminate.

2) Verify Wiring Configuration. A common misconception is that because the existing installation is TIA/EIA-568A compliant, the wiring configuration is, therefore, 568A. However, you could have a TIA/EIA-568A compliant installation with 568A or 568B wiring since either is acceptable. When adding to the current infrastructure, it would be a mistake to wire to 568B when the current configuration is 568A, or visa versa. For new installations, verify user requirements and be consistent for the entire installation.

3) Communicate with the Customer to ensure that all parties involved are clear on what is to be done. It is not unusual for a customer to change their mind on where they want a particular wall outlet, the total number of stations, the color of wall plates or other particulars in the middle of the job. A pre-installation walk through with the customer, going over placement of jacks, wall plate color, panel locations in the wiring closet and so on can help avoid problems down the road.

4) Map Out All Cable Pathways before pulling any cable. In a typical drop-ceiling installation, start at the wall outlet and work your way back to the closet moving ceiling tiles, checking to be sure that you have a clear path for the cable. Once the path has been determined, install support hardware necessary (e.g. J-hooks or bridle rings). Now, you are ready to fish and/or place your pull string and begin pulling cable. This step may seem obvious, but much time can be wasted due to improper planning for the cable pull.

5) Group Station Cables coming from the patch panel in bundles that correspond to the port grouping on the panel. This will better facilitate troubleshooting and changes. For instance, jacks are organized in groups of six on the panel. Therefore, bundle station cables accordingly such that cables 1-6 constitute your first bundle, cables 7-12, your second bundle and so on.

6) When Punching Down on a 110 Block DO NOT untwist the pair to place the conductors in the slots. Instead, spread the pair apart just enough to allow it to be pushed over the colored dividing post on the block. This technique will leave the pair twisted above and below the point of termination, holding the pair in place while you use the punchdown tool. It will also maintain the pair twist as close as possible to the point of termination. ANSI/TIA/EIA-568A states that for Category 5 cables the amount of untwisting in a pair as a result of termination to connecting hardware shall be no greater than 13 mm (0.5 ").

7) Do Not Use Stranded Category 5 Cable for Horizontal Cabling Runs. Stranded Category 5 is intended for use in patch cables and will not pass the required testing when used for horizontal runs, which are longer than patch cables. ANSI/TIA/EIA 568A only allows for 10 meters total of patch cables including the workstation cables and equipment/patching cables in the closet.

8) Do Not Use more than 25 lbs. of Pulling Tension on Category 5 Cable. The recommended maximum pulling tension for four pair Category 5 cable is 25 lbs. Greater tension can deform the cable, stretch the pairs and change the performance characteristics of the cable, possibly causing it to fail the required tests. Use a 25 lb. breakaway swivel or a 25 lb. fishing line attached between the pull rope and the cable.

9) Verify that You Have the Correct Plug Wire for the wire you are using when crimping modular plugs. Solid and stranded wire use different plugs. While some solid wire plugs may work on stranded cable, you cab generally be sure that stranded wire plugs will not be compatible with solid wire. The difference is in the way the IDC (insulation displacement connector) pins make contact with the conductor. The plug for stranded wire typically pierces into the insulation going between the strands. The plug for wires has fingers that straddle the solid connector, penetrating the insulation on both sides and making contact with the conductor.

10) Beware of the Cut Sides of a Punchdown Tool. When using the cutting side of a punchdown blade, make sure that the tool is oriented such that you cut the excess and not the conductor. Most punchdown tools are marked "CUT" on one side to help to remind you which side will cut. Seems simple but many experienced installers make this mistake.

11) When Running Cable in a Non-insulated Wall, your best tool is a fish tape. Alternately, tie a fisherman's sinker, heavy bolt or heavy nut to a piece of string and lower from above , lined up with the intended opening in the wall.

12) Identify the Cables. Labeling all cables at both ends during installation helps to avoid sorting through the mess after everything is pulled. Use numbering labels to mark the individual cables to be pulled. Using a marking pen, write the corresponding number on the box or spool of cable. After each pull is completed, use the labels to again mark each cable Before You Cut, marking each according to the number you have written on the boxes or spools. When preparing to pull the next group of cables, simply cross out the previous number(s) on the boxes or spools and repeat the procedure. All cables will now be labeled at both ends.

13) Common Causes of Category 5 Test Failures
* Cable tie cinched too tight - this will crush the cable, deforming the pair twists and changing the performance characteristics of the cable.
* Too tight of a bend radius on cable (min four times diameter for 4-pair Cat 5) - tight bends will deform the pair twists and change the performance characteristics of the cable.
* Not punched down properly, pairs or conductors reversed - pair reversal or improper termination will cause pairs to be routed to incorrect pins on modular jacks. You may lose end-to-end continuity.
* Pair untwisted too much at termination point (must be no more than 1/2" untwisted) - attenuation and crosstalk performance of cable is impacted greatly.
* Too much pulling tension used on cable during installation (do not exceed 25 lbs.) - pair twists become stretched or otherwise deformed, changing the performance characteristics of the cable.
* Configuration mismatch between jack and panel - pairs are routed to different pins on each end of the horizontal run and end-to-end continuity is altered such that a straight-through connection is not achieved.
* Sub-Category 5 cable, panel and jack used - Sub-Category 5 cable and/or connecting hardware may not pass the required testing.
* Horizontal cable run exceeds maximum (90 meters) - besides being non-compliant with the standards, this could have an adverse impact on LAN (Local Area Network) performance.
* Stranded Category 5 used for horizontal run - stranded cable is designed for use in shorter runs from the wall outlet to the workstation or between panels and/or equipment in the closet. They may not pass the required testing when used for longer runs.


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Glossary

ANSI/TIA/EIA-568A
Commercial Building Telecommunications Cabling Standard produced by the TIA (Telecommunications Industry Association).

Attenuation
The decrease in magnitude of voltage (power), or of a signal in transmission between points. Measured in decibels (dB), it expresses the total losses on a transmission line based on a ratio of output power to input power. Attenuation in data transmissions is most greatly affected by cable length and the frequency of transmission.

Crosstalk
Signal induced into a cable by another transmitting pair. The simplest example is one telephone conversation heard "bleeding" over into another.

Jack
Female modular connector mounted in a wall plate or patch panel.

Horizontal Cabling
The portion of the cabling system that runs between and including the patch panel (a.k.a. crossconnect) and the jack in the workstation outlet (wall plate).

Modular Plug
Small, usually clear plastic, connector used on the end of patch cables. The connector uses insulation displacement to make contact with the conductors in the wire. It is crimped on the end of the cable which has had the jacket removed, but the insulation on the conductor is intact. The modular plug can come in several varieties from 4-position handset to 10-position. The plug used for residential phones is the 6-position, 4 or 6 conductor (RJ11). The plug used for Category 5 patch cables is the 8-position, 8 conductor (RJ45).

Patch Panel
Rack mount panel used in telecommunications closest as a point of crossconnect. Typically, patch panels have 110 style IDC (insulation displacement) connections on the back of the panel and the modular jacks on the front.

Pinout
(See Wiring Configuration below)

Port Grouping
Modular jacks on the front of the patch panels are normally found in groupings of 4, 6 or 8 on the panel. A 24 port panel may have one row of jacks consisting of 6 groups of 4 jacks, 4 groups of 6 jacks or 3 groups of 8 jacks, depending on the manufacturer's design.

Station Cables
Also known as the Horizontal Cabling. The individual cables that run from the workstation outlets (wall plates) back to the horizontal crossconnect (patch panel) in the telecommunications closet.

Wiring Configuration (Pinout)
Specific Conductors on the cable are assigned to specific pins on the modular jack, 110 connectors and TELCO connectors.


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