Network Cable Central
Get informed about Cat5 & Cat5e.
Since the most popular category of computer network cable is cat5e, I’d like to address some of the most common misconceptions about it. I’d also like to shed some light on the “tricks” many retailers of cat5e cable will use to confuse the buyer.
Category 5 Cable (Cat5) consists of four twisted pair cables for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video. The cable is commonly connected using punch down blocks and modular connectors. Category 5 (Cat5) has been superseded by the Category 5e (Cat5e) specification (these categories are handed down by the American National Standards Institute or “ANSI”). Cat5e will support Ethernet, Fast Ethernet, and Gigabit Ethernet (10/1000). “e” is completely backwards compatible. Cat5e is normally what is used in most applications as of 2011.
If someone knew they had special needs, then they would probably know which category of network cable is required. If they don’t specify, then it’s a safe bet they are OK with Cat5e cable.
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For the record, cat5e is superior to regular cat5 by less cross talk (electrical interference), a thicker PVC or PE protective jacket, and increased bandwidth (the amount of information it can carry). The differences are significant and even an un-technical user would notice a difference in performance. It’s hard to go wrong with cat5e network cable.
Shielded (STP) vs. Unshielded (UTP)
Unshielded Twisted Pairs (UTP) is the most common cable used in computer networking. When you go to the store a buy a 25ft Ethernet cable it’s most likely a UTP cat5e patch cable (“patch” means it’s used to connect one device to another and has the plastic caps on the end all ready to go). Shielded Twisted Pairs (STP) means the cable is constructed in such a way that it prevents electromagnetic interference. The STP cable will have a grounding wire or “drain” wire inside so the metal shielding foil will work. Retailers really start to confuse buyers when they start talking about STP cable. When you do a Google search for “STP cat5e cable” you are likely to see a lot of cable advertised as STP. Please read the specifications carefully because in the US many people use STP as a generic term. There are different types of shielding, some more expensive than others. Sewell Direct, for example, will advertise as STP but will ALWAYS specify the type of shielding used in the cable.
The two common types of STP shielding are “BRAIDED SHIELDING” and “FOIL SHIELDING”. Braided shielding has a tinned copped braid shield wrapped around the entire group of twisted pairs. It is usually described as “65% Braided Coverage” or however much surface area the braid physically covers. The more coverage, the more electromagnetic interference is blocked. Foil shielding is an aluminum-mylar foil shield that is wrapped around the group of twisted pairs. In Asia, for example, foil shielded cable is referred to as FTP and braided shield cable is referred to as STP. For whatever reason, most people in the US will use the term STP very liberally and often mistakenly. No matter what, just make sure you have a clear description of the cable. *Note: You can also get cable that has foil shielding around each set of twisted pairs. It is not as common, but it is available if needed.
Below is a chart showing commonly used terms for cat5e cable. The “new name” is the approved abbreviation consistent with the international ISO standard 11801. This doesn’t mean everyone uniformly uses it, however.
|Old Name||New Name||Cable Screening||Pair Shielding|
The code before the slash designates the shielding for the cable itself, while the code after the slash determines the shielding for the individual pairs:
Bulk Cat5e cable available through Sewell Direct: (click to follow)
Pure Copper vs. CCA (Copper Clad Aluminum)
If you search around the internet, you’ll see people trashing CCA cat5e Ethernet cable. Copper clad aluminum consists of an aluminum wire that is coated or “clad” in copper. A pure copper wire is definitely the top of the line (assuming the copper is a good quality), however in these tough economic times many people are sensitive to the high prices of copper cables. Critics will tell you that CCA lacks significant performance measures. The truth is there are different grades of CCA cable. Some bad manufacturers will build a CCA cable that is only 5% copper content by volume. This is generally unacceptable in most applications and unreliable to provide typical cat5e performance. I have found that minimum 25% copper content by volume is acceptable for 95% of the applications. For the most part, only a very technical user with high performance demands would even notice a difference. A good CCA cat5e cable will easily match the cat5e performance standards. Some critics of CCA will say that pure copper will last longer, and while that may be true it will likely never be a factor since by the time it corrodes or falls apart you’ll probably have a new technology wired in your walls anyway. Make sure you ask your retailer what the copper content by volume of their CCA cat5e is, and if they do not know don’t buy it. CCA can cost 50% of the typical pure copper cable, so weigh the risks accordingly.
Cat5e network cable must meet or exceed the ANSI standard of 100 MHz with regard to bandwidth (or the size of the “pipe” in which information can flow). It is very common for pure copper cat5e to go up to 350 MHz. For most applications, the user will not see much difference in day-to-day usage whether their cable is rated exactly at 100 MHz or 350 MHz. Retailers should specify if the cable will operate at 350 MHz, if not then you can assume it still meets the standard 100 MHz for cat5e network cable.
Solid vs Stranded
Cat5e cable can be described as either SOLID or STRANDED. This term refers to how the conductor (whether pure copper or CCA) is constructed. When you buy a patch cable from the store, you are most likely buying a stranded cable. Stranded cable is generally regarded as more flexible, since the conductor is “stranded” together in smaller pieces. Stranded cable is also a little less expensive to manufacture. Solid cat5e conductors are typically used for longer runs such as running from room to room, etc. All things being equal, you will see a little better performance from solid cable as opposed to stranded, especially over long runs of hundreds of feet. Unless you plan on tying your cable in knots, any solid cat5e conductor cable should be sufficient.
PE Jacket vs. PVC Jacket
The outer protective covering that you see is called the cable “JACKET”. It is commonly made out of PVC (Polyvinyl Chloride) or PE (Polyethylene) material. For most common in-wall applications PVC is the most traditional, but PE is about the same cost yet can offer a little better protection against temperature extremes and durability. There are obviously different types of applications and environments in which a cable can be installed. Underwriter Laboratories (UL) provides some uniformity in the classes of jacket types. Typical in-wall rating is referred to a CM or CMG class (Communications General). Low smoke insulation PVC jackets that are rated for RISER use are called CMR. A higher class of smoke and flame resistant PVC jacket is rated PLENUM and is classified as CMP. Another common rating is applied to ULTRAVIOLET coating in the jacket called CMX. This is for outdoor applications.
Bulk Cat5e cable available through Sewell Direct: (click to follow)