Cat 6 cable (listed in the standard as Category 6) is a standardized cable for 1000GBASE-T (Gigabit Ethernet) that is backward compatible with Category 5/5E and Category 3. It is also suitable for 10GBASE-T (10-Gigabit Ethernet), 10BASE-T, and 100 BASE-TX (Fast Ethernet). New installations often specify Cat 6 cable. It is important for professional installers to understand the requirements of the newer standard and know how to create a standard cat 6 patch cable.
Differences With Cat 5 Cable
Whereas Cat5E cable is only characterized up to 350 MHz, Cat 6 allows up to 550 MHz operation. The greatest performance improvement for Category 6 cable is its increased immunity to alien crosstalk. This type of crosstalk is coupling between nearby connections. In some cases, users can hear other people’s conversations on their line, thus the term crosstalk. The biggest foil to crosstalk is that the 8 cable wires are matched in sets of 4 twisted pairs. Each pair is fed differentially, and common-mode signals (signals which are the same on both wires, such as crosstalk coupling) are rejected. A second technique for reducing crosstalk is to use digital signals, which are inherently resistant.
It is easy to differentiate Category 6 cable by the printing on the side of the sheath. Connectors use either TIA standard T568A or T568B pin assignments. Some technicians get away with alternate configurations. This works as long as both ends of the cable are connected the same way. However, it is not a recommended practice in case another technician comes in to repair one end of the cable later.
Although Cat 6 connectors have the same 8P8C look as Cat 5E and other earlier versions, it is important to use cat 6 rated jacks, connectors, and cables, or the improved Category 6 performance will be degraded.
In order to meet Cat 6 specs, installation is everything. Make sure not to kink the cable. This can happen if the bend radius is less than four times the cable diameter. A common installation mistake is to strip the insulation back more than 0.5 in (12.7 mm). Another common problem is allowing the twisted pairs to unravel past the skin point, creating a crosstalk vulnerability point at the connector.
High EMI (electromagnetic interference) environments require special handling. This type of environment may occur when cabling is within a few feet of a power plant, a high power electric motor, high power switches, or other heavy EMI generators. Cable shielding preserves the Category 6 specs and is enhanced by connecting to a drain wire. This wire runs through the actual cable alongside the groups of twisted pairs.
According to Cat 6 directives, the cable shielding is connected to true ground at each cable end through jacks. Unfortunately, this violates the rule of only grounding one side of a shield in order to avoid creating a ground loop. Installers must be careful to place each cable to avoid having a voltage differential from one end of the cable to the other. If this happens, extraneous currents may be generated in the cable, increasing system noise.
How to Make a Patch Cable
Start by assembling the proper tools:
• Category 6 cutter/stripper
• Plugs – these are different for stranded or solid connectors. They are nearly impossible to differentiate visually, so be sure to keep them separate after you make the purchase.
• Boots (optional)
Now complete the following steps:
• Cut the cable to length and strip to 0.5”. Use the boots facing outwards, if desired.
• Carefully untwist the cable pairs – do not go further than the strip.
• Bend the center spine away from the conductor wires and cut at the strip.
• Bring the wires together and cut at a sharp angle.
• Bring the wires together and insert them into the loadbar. Use a 568B wiring diagram. (For a crossover cable, follow the 568A wiring diagram at one end only.)
• Check the wire order one more time, and then make a perfectly straight cut 0.25” past the loadbar.
• Place the connector onto the loadbar assembly. Make sure the copper connectors are up and the locking clip is facing down.
• Make the crimp, squeezing all the way down.
• Repeat the procedure at the other end.
Test the Assembly
Be sure to perform a continuity check religiously with each cable assembly. Consider using a high-quality four-pair tester. If the cable fails, try giving another crimp at each end. If necessary, check the wires by color for the proper positioning. Make sure each wire extends to the connector end and that the pins are pushed down fully. If it still does not work, clip off one connector and try again. If there is still a problem, repeat the examination, focusing in on the end with the original connector. Finally, high-performance 10GBASE-T will need to be tested in situ for alien crosstalk.
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