Category 5 cable
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Category 5 cable is a twisted pair high signal integrity cable type often referred to as Cat5 or Cat-5. Most cables are unshielded, relying on the twisted pair design for noise rejection, and some are shielded. Category 5 has been superseded by the Category 5e specification structured cabling for computer networks such as Ethernet, and is also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances).
Usage and wiring methods
Category 5
The specification for Category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specified performance characteristics and test requirements for frequencies of up to 100 MHz.
Category 5 cable includes twisted pairs in a single cable jacket. This use of balanced lines helps preserve a high signal-to-noise ratio despite interference from both external sources and other pairs (this latter form of interference is called crosstalk). It is most commonly used for 100 Mbit/s networks, such as 100BASE-TX Ethernet, although IEEE 802.3ab defines standards for 1000BASE-T – Gigabit Ethernet over category 5 cable. Cat 5 cable typically has three twists per inch of each twisted pair of 24 gauge (AWG) copper wires within the cables.
Manufacture of Solid Core Cable
Copper Rod Breakdown The first step in low voltage cable production is copper rod breakdown. Copper is sent to the factory in 5,000 lb coils. These copper coils are continuously drawn through diamond dies that drastically reduce the diameter of the copper to 10 or 12 gauge. Lubrication is used during this process to reduce the amount of friction and heat on the copper cable. Once completed, the copper is stacked in vertical coils, called Stem Packs. These stem packs are then transferred to another drawing operation that further reduces the gauge of the copper. During this stage, the copper is also charged with an electrical current. This anneals the copper, which is a softening process. Once annealed and cooled off, the copper runs through a laser measurement system, to verify it is within manufacturing specifications.
Copper Insulation Process
The copper insulation process is continually monitored and controlled up to +/- .0001". Once the copper is insulated, it runs through a water cooling trough, allowing the wire jacket to properly harden.
Copper Twisting
Twisting helps reduce crosstalk between the individual pairs of wire. Some Cat6 premise cables include a center spline, or wire separator, to further reduce crosstalk and increase performance. Copper twisting is accomplished by running each individual wire through multiple faceplates. This helps control pair position. Once twisted, we have what's called a Cable Unit.
Jacketing
The cable unit then goes through the jacketing process. This step varies, depending on the type of cable being manufactured. OSP cable typically uses a black polyethylene or UV rated Polyvinyl chloride (PVC). For Cat3, Cat5e and Cat6 Premise cable, varying grades of PVC are used, depending on flame safety rating requirements. This step begins with molten plastic being extruded at high pressure and formed around the moving cable core. Shielding, ripcords, armoring and water blocking compound may also be applied at this step. Cables that require dual shielding or double armor will need to repeat this process. Once completed, the cable passed through a long cooling bath, then through a laser micrometer to verify the final diameter.
Printing
Printing is done just before the cable is put in its final packaging. For OSP cable, a hot foil printing process is used, that leaves an indented print in the cable jacket. For Premise cable, a high speed ink jet printer is used. Some cable manufacturers print footage marking from 1000–0 ft, making it very easy to determine how much cable is left in the box, or for measuring out cable runs. Other manufacturers use a six digit footage mark, making the process a little harder.
Coiling
The completed cable is then wound onto a reel or coil. The coiling process requires very precise tension controls to ensure the cable won't tangle when being pulled out of the box.
Final Testing
Once the cable is printed and coiled, it goes through one last set of tests. The manufacturer will test it against a large set of mechanical and electrical performance specifications. Once tested, the cable is ready for shipment.
Solid core Cable vs Stranded Cable
Solid core cable is supposed to be used for long permanently installed runs. It is less flexible than stranded and more prone to failure if repeatedly flexed. Stranded cable is used for fly leads at patch panel and for connections from wall-ports to end devices, as it resists cracking of the conductors. Stranded core is generally more expensive than solid core.
Connectors need to be designed differently for solid core than for stranded. Use of a connector with the wrong cable type is likely to lead to unreliable cabling. Plugs designed for solid and stranded core are readily available, and some vendors even offer plugs designed for use with both types. The punch-down blocks on patch-panel and wall port jacks are designed for use with solid core cable.
The maximum specified distance for Cat5 cable is 100m. This allows for 10m of stranded cable at either end. Solid core has less attenuation than stranded cable, so a switch-to-switch link of solid cable, where the only connections are cable-plug-switch at either end can be significantly longer than 100m in practice. Experiments show that the practical limit is around 200m for 100 Mb/s. 1000Mb/s is intermittent at 200 m. These distances depend a little on the individual switches.
Copper-clad aluminium
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The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page.
The American market had also been flooded with copper clad cable imported mostly from China and falsely presented in the market as being a 100% copper Cat 5e cable. With less copper involved in the manufacturing process, the cost to the consumer is lower, yet the consumer is not getting a true 100% copper Cat 5e cable.
Installation of copper clad aluminium Cat 5e wire has also been proven — by low-voltage contractors in the Southern California market, where this cable first arrived — to have poor test results and often not passing the Category 5e transmission standard. Since copper conducts electricity better than aluminium, signal strength has also been proven to be very weak over long runs using this substandard cable.
Additionally, some manufacturers have also falsely represented their Cat 5e cable conductors as being 24 AWG. In actuality, a 26 AWG conductor is being sold and is hard to detect unless further examination beneath the sheath of the conductor is performed. A 26 AWG Cat 5e cable will not make proper contact on Cat 5e jack modules as most jack modules require 22 or 24 AWG per the specification and qualified connectors.
The United States Federal Government will not accept bids from China for Cat 5e cable due to China being absent from the Trade Agreements Act of 1979. In general, a product is only "TAA compliant" if it is made in the United States or a "Designated Country".
The Cat 5e “350 MHz” debacle
The 350 MHz term started a couple of years before the arrival of Category 6 cable by the Belden Electronics Division and promised better performance. Although the performance of this new 350 MHz cable was slightly better it was an easy way to sell the consumer on future proofing their needs while charging around 15% more and leading to a higher margin on the 350 MHz cable than the standard 5e cable. Soon after many other manufactures also offered a 350 MHz cable and followed the trend of an easy way to add to a higher margin. Some low-end cable manufacturers have the term “tested to 350 MHz” printed on the jacket as a way to appear to the consumer that they are receiving a better quality of 5e cable, but the cable was only “tested to 350 MHz” and no promise of a performance guarantee is ever mentioned.
As the 350 cable and term gained momentum, many manufacturers began offering a 400 MHz 5e cable, a 550 MHz 5e cable, and so on. This led to the consumer and communications contractor assuming and leaving them confused that the higher a MHz rating meant for a better performing cable. The arrival of the Category 6 cable standard which specified a delivered performance at 250 MHz left many people confused.
EIA Electronic Industries Alliance / TIA Telecommunications Industry Association only recognize the Category 5e standard TIA/EIA-568-B.2-2001 as guaranteeing performance of attenuation, NEXT, Power-sum NEXT, ACR, power-sum ACR, ELFEXT, power-sum ELFEXT, return loss, propagation delay and delay skew at 100 MHz. No standard is issued for 350 MHz cable and review of manufacturer spec sheets such as General Cable, Superior Essex, and Berktek show us different performance numbers for 350 MHz. With no standard for 350 MHz cable, promised performance, if any, will vary from manufacturer to manufacturer and leave the consumer and contractor to continue to be confused.
Connectors and other information
The cable exists in both stranded and solid conductor forms. The stranded form is more flexible and withstands more bending without breaking and is suited for reliable connections with insulation piercing connectors, but makes unreliable connections in insulation-displacement connectors. The solid form is less expensive and makes reliable connections into insulation displacement connectors, but makes unreliable connections in insulation piercing connectors. Taking these things into account, building wiring (for example, the wiring inside the wall that connects a wall socket to a central patch panel) is solid core, while patch cables (for example, the movable cable that plugs into the wall socket on one end and a computer on the other) are stranded. Outer insulation is typically PVC or LSOH.
Cable types, connector types and cabling topologies are defined by TIA/EIA-568-B. Nearly always, 8P8C modular connectors, often incorrectly referred to as "RJ-45", are used for connecting category 5 cable. The specific category of cable in use can be identified by the printing on the side of the cable.
The cable is terminated in either the T568A scheme or the T568B scheme. Canada uses the T568A standard, and the United States commonly uses T568B scheme. It really doesn't make any difference which is used as long as you use only one of the standards so all connections are the same at your location to avoid confusion and potential problems. Mixed cable types should not be connected in series as the impedance per pair differs slightly and may cause signal degradation. The article Ethernet over twisted pair describes how the cable is used for Ethernet, including special "cross over" cables.
Conductors required
10BASE-T (IEEE) and 100BASE-TX (IEEE) Ethernet connections require two cable pairs. 1000BASE-T (IEEE) and 1000BASE-TX (TIA/EIA-854, requiring category 6 cabling, unimplemented) Ethernet connections require four cable pairs. Four pair cable is by far most commonly available type.
Bending radius
Most Cat.5 cables can be bent at a radius approximately 4 times the diameter of the cable.
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