Saturday, October 29, 2011

Why Pick Copper Cabling?

Copper cabling has been around and in use since electricity was invented. And the quality of copper wire has continued to improve. Over the past 100 years, copper manufacturers have developed the refining and drawing processes so that copper is even more high quality than when it was first used for communication cabling.
High-speed technologies (such as 155Mbps ATM and 10 Gigabit Ethernet) that experts said would never run over copper wire are running over copper wiring today.
Network managers pick copper cabling for a variety of reasons: Copper cable (especially UTP cable) is as inexpensive as optical fiber and easy to install, the installation methods are well understood, and the components (patch panels, wall-plate outlets, connecting blocks, etc.) are inexpensive. Further, UTP-based equipment (PBX systems, Ethernet routers, etc.) that uses the copper cabling is much more affordable than comparable fiber equipment.
The main downsides to using copper cable are that copper cable can be susceptible to outside interference (EMI), copper cable provides less bandwidth than optical fiber, and the data on copper wire is not as secure as data traveling through an optical fiber. This is not an issue for the typical installation.
Table 1 lists some of the common technologies that currently use unshielded twisted-pair Ethernet. With the advances in networking technology and twisted-pair cable, it makes you wonder what applications you will see on UTP cables in the future.
Table 1: Applications That Use Unshielded Twisted-Pair Cables 
Data Rate
Encoding Scheme[*]
Pairs Required
10Base-T Ethernet
100Base-TX Ethernet
100Base-T4 Ethernet
1000Base-T Gigabit Ethernet
10GBase-T Gigabit Ethernet
100Base-VG AnyLAN
4Mbps Token Ring
16Mbps Token Ring
TP-PMD (FDDI over copper)
[*]Encoding is a technology that allows more than one bit to be passed through a wire during a single cycle (hertz).

Wednesday, October 26, 2011

Picking the Right Patch Cables

Although not really part of a discussion on picking cable types for horizontal cable, the subject of patch cords should be addressed. Patch cables (or patch cords) are the cables that are used to connect 110-type connecting blocks, patch-panel ports, or telecommunication outlets (wall-plate outlets) to network equipment or telephones.
We've mentioned this before but it deserves repeating: you should purchase factory-made patch cables. Patch cables are a critical part of the link between a network device (such as a PC) and the network equipment (such as a hub). Determining appropriate transmission requirements and testing methodology for patch cords was one of the holdups in completing the ANSI/TIA/EIA-B.2-1 Category 6 specification. Low-quality, poorly made, and damaged patch cables very frequently contribute to network problems. Often the patch cable is considered the weakest link in the structured cabling system. Poorly made patch cables will contribute to attenuation loss and increased crosstalk.
Factory-made patch cables are constructed using exacting and controlled circumstances to assure reliable and consistent transmission-performance parameters. These patch cables are tested and guaranteed to perform correctly.
Patch cables are made of stranded-conductor cable to give them additional flexibility. However, stranded cable has up to 20 percent higher attenuation values than solid-conductor cable, so lengths should be kept to a minimum. The ANSI/TIA-568-C standard allows for a 5-meter (16) maximum-length patch cable in the wiring closet and a 5-meter (16) maximum-length patch cable at the workstation area.
Here are some suggestions to consider when purchasing patch cables:
  • Don't make them yourself. Many problems result from bad patch cables.
  • Choose the correct category for the performance level you want to achieve.
  • Make sure the patch cables you purchase use stranded conductors for increased flexibility.
  • Purchase a variety of lengths and make sure you have a few extra of each length.
  • Consider purchasing patch cords from the same manufacturer that makes the cable and connecting hardware, or from manufacturers who have teamed up to provide compatible cable, patch cords, and connecting hardware. Many manufacturers are a part of such alliances.
  • Consider color-coding your patch cords in the telecommunication closet. Here's an example:
    • Blue cords for workstations
    • Gray cords for voice
    • Red cords for servers
    • Green cords for hub-to-hub connections
    • Yellow for other types of connections

Sunday, October 23, 2011

Types of Copper Cabling

Pick up any larger cabling catalog, and you will find myriad types of copper cables. However, many of these cables are unsuitable for data and voice communications. Often, cable is manufactured with specific purposes in mind, such as audio, doorbell, remote equipment control, or other low-speed, low-voltage applications. Cable used for data communications must support high-bandwidth applications over a wide frequency range. Even for digital telephones, the cable must be chosen correctly.
Many types of cable are used for data and telecommunications. The application you are using must be taken into consideration when choosing the type of cable you will install.Table 1 lists some of the historic and current copper cables and common applications run on them. With the UTP cabling types found in Table 1, applications that run on lower-grade cable will also run on higher grades of cable (for example, digital telephones can be used with Category 3, 4, 5, 5e, 6, or 6A cabling). Category 1, 2, 4, and 5 are no longer recognized by ANSI/TIA-568-C and should be avoided, but they are described below for historical purposes.

Table 1: Common Types of Copper Cabling and the Applications That Run on Them 
Cable Type
Common Applications
UTP Category 1 (not supported by ANSI/TIA-568-C)
Signaling, doorbells, alarm systems
UTP Category 2 (not supported by ANSI/TIA-568-C)
Digital phone systems, Apple LocalTalk
UTP Category 3
10Base-T, 4Mbps Token Ring
UTP Category 4 (not supported by ANSI/TIA-568-C)
16Mbps Token Ring
UTP Category 5 (not supported by ANSI/TIA-568-C)
100Base-TX, 1000Base-T
UTP Category 5e
100Base-TX, 1000Base-T
UTP Category 6
100Base-TX, 1000Base-T
UTP Category 6A
100Base-TX, 1000Base-T, 10 Gigabit Ethernet
Multi-pair UTP Category 3 cable
Analog and digital voice applications; 10Base-T
25 pair UTP Category 5e cable
10Base-T, 100Base-T, 1000Base-T
Shielded twisted-pair (STP or U/FTP)
4Mbps and 16Mbps Token Ring
Screened twisted-pair (ScTP or F/UTP)
100Base-TX, 1000Base-T, 10 Gigabit Ethernet
Coaxial RG-8
Thick Ethernet (10Base-5), video
Coaxial RG-58
Thin Ethernet (10Base-2)
Coaxial RG-59
CATV (community antenna television, or cable TV)
Coaxial RG-6/U
CATV, CCTV (Closed Circuit TV), satellite, HDTV, cable modem
Coaxial RG-6/U Quad Shield
Same as RG-6 with extra shielding
Coaxial RG-62
ARCnet, video, IBM 3270

Wednesday, October 19, 2011

Tools That a Smart Data Cable Technician Carries

Up to this point, all the tools we've described are specific to the wire-and-cable installation industry. But you'll also need everyday tools in the course of the average install. Even if you don't carry all of these (you'd clank like a knight in armor and your tool belt would hang around your knees if you did), you should at least have them handy in your arsenal of tools:
  • A flat blade screwdriver and number 1 and number 2 Phillips screwdrivers. Power screwdrivers are great time-and-effort savers, but you'll still occasionally need the hand types.
  • A hammer.
  • Nut drivers.
  • Wrenches.
  • A flashlight (a no-hands or headband model is especially handy).
  • A drill and bits up to 1.5.
  • A saw that can be used to cut rectangular holes in drywall for electrical boxes.
  • A good pocket knife, electrician's knife, or utility knife.
  • Electrician's scissors.
  • A tape measure.
  • Face masks to keep your lungs from getting filled with dust when working in dusty areas.
  • A stud finder to locate wooden or steel studs in the walls.
  • A simple continuity tester or multitester.
  • A comfortable pair of work gloves.
  • A sturdy stepladder, preferably one made of nonconductive materials.
  • A tool belt with appropriate loops and pouches for the tools you use most.
  • Two-way radios or walkie-talkies. They are indispensable for pulling or testing over even moderate distances or between floors. Invest in the hands-free models that have a headset, and you'll be glad you did.
  • Extra batteries (or recharging stands) for your flashlights, radios, and cable testers.
Here's an installation tip: Wall-outlet boxes are often placed one hammer length from the floor, especially in residences (this is based on a standard hammer, not the heavier and longer framing hammers). It's a real time-saver, but check the boxes installed by the electricians before you use this quick measuring technique for installing the data communications boxes so that they'll all be the same height.
A multipurpose tool is also very handy. One popular choice is a Leatherman model with a coax crimper opening in the jaws of the pliers. It's just the thing for those times when you're on the ladder looking down at the exact tool you need lying on the floor where you just dropped it.
One of the neatest ideas for carrying tools is something that IDEAL DataComm calls the Bucket Bag (pictured in Figure 1). This bag sits over a five-gallon bucket and allows you to easily organize your tools.

Figure 2: IDEAL DataComm's Bucket Bag

Sunday, October 16, 2011

Cable-Marking Supplies

One of the worst legacies of installed cabling systems (and those yet to be installed) is a profound lack of documentation. If you observe a professional data cable installer in action, you will notice that the cabling system is well documented. Though some professionals will even use color coding on cables, the best start for cable documentation is assigning each cable a number. ANSI/TIA-606-B provides specifications about how to document and label cables.

Cable-Marking Labels

The easiest way to number cables is to use a simple numbering system consisting of strips of numbers. These strips are numbered 0 through 9 and come in a variety of colors. Colors include black, white, gray, brown, red, orange, yellow, green, blue, and violet. You can use these strips to create your own numbering system. The cable is labeled at each end (the patch panel and the wall plate), and the cable number is recorded in whatever type of documentation is being used.
The numbered strips are often made of Tyvek, a material invented by DuPont that is well suited for making strong, durable products of high-density polyethylene fibers. Tyvek is nontoxic and chemically inert, so it will not adversely affect cables that it is applied to.
These wire-marking labels are available in two flavors: rolls and sheets. The rolls can be used without dispensers. Figure 1 shows a 3M dispenser that holds rolls of wire markers; the dispenser also provides a tear-off cutting blade.

Figure 1: A 3M dispenser for rolls of wire-marking strips
Figure 2 shows a booklet of wire-marker sheets that allow you to pull off individual numbers.
Figure 2: A booklet of wire-marker sheets

Wall-Plate Marking Supplies

Some wall-plate and patch-panel systems provide their own documentation tools, but others don't. A well-documented system includes identifying labels on the wall plates. Figure 3 shows self-adhesive letters, numbers, and icons that can be used with wall plates and patch panels. Check with the manufacturer of your wall plates and patch panels to see if these are part of the system you are using; if they are not, you should use some such labeling system.

Figure 3: Letters, numbers, and icons on self-adhesive strips

Thursday, October 13, 2011

Wire-Pulling Lubricant

Wire- or cable-pulling lubricant is a slippery, viscous liquid goop that you apply to the cable jacket to allow it to slide more easily over surfaces encountered during the cable pull. Wire lubricant (see Figure 1) is available in a variety of quantities, from less than a gallon to five-gallon buckets.

Figure 1: Wire-pulling lubricant
The vast majority of cable jackets for premises cables in the United States are made out of some form of PVC. One characteristic of PVC is that, depending on the specific compound, it has a relatively high coefficient of friction. This means that at the microscopic level, the material is rough, and the rough surface results in drag resistance when the cable jacket passes over another surface. Where two PVC-jacketed cables are in contact, or where PVC conduit is used, the problem is made worse. Imagine two sandpaper blocks rubbing against each other.
In many cases, the use of pulling lubricant is not necessary. However, for long runs through conduit or in crowded cable trays or raceways, you may find either that you cannot complete the pull or that you will exceed the cable's maximum allowable pulling tension unless a lubricant is used.
The lubricant is applied either by continuously pouring it over the jacket near the start of the run, or by wiping it on by hand as the cable is pulled. Where conduit is used, the lubricant can be poured in the conduit as the cable is pulled.
Lubricant has some drawbacks. Obviously, it can be messy; some types also congeal or harden over time, which makes adjustment or removal of cables difficult because they are effectively glued in place. Lubricant can also create a blockage in conduit and raceways that prevents new cables from being installed in the future.
Make sure the lubricant you are using is compatible with the insulation and jacket material of which the cables are made (hint: don't use 10W30 motor oil). The last thing you need is a call back because the pulling lubricant you used dissolved or otherwise degraded the plastics in the cable, leaving a bunch of bare conductors or fibers. Also check with the manufacturer of the cable, as the use of certain lubricants may void the warranty of the cable.

Monday, October 10, 2011

Cabling Supplies and Tools

When you think of cabling supplies, you probably envision boxes of cables, wall plates, modular connectors, and patch panels. True, those are all necessary parts of a cabling installation, but you should have other key consumable items in your cabling tool kit that will make your life a little easier.
Some of the consumable items you may carry are fairly generic. A well-equipped cabling technician carries a number of miscellaneous items essential to a cabling install, including the following:
  • Electrician's tape—multiple colors are often desirable
  • Duct tape
  • Plastic cable ties (tie-wraps) for permanent bundling and tie-offs
  • Hook and loop cable ties for temporarily segregating and bundling cables
  • Adhesive labels or a specialized cable-labeling system
  • Sharpies or other type of permanent markers
  • Wire nuts or crimp-type wire connectors
An item that most cable installers use all the time is the tie-wrap. Tie-wraps help to make the cable installation neater and more organized. However, most tie-wraps are permanent; you have to cut them to release them. Hook-and-loop (Velcro-type) cable wraps (shown in Figure 1) give you the ability to quickly wrap a bundle of cable together (or attach it to something else) and then to remove it just as easily. The hook-and-loop variety also has the advantage of not over-cinching or pinching the cable, which could cause failure in both optical fiber and copper category cables. Hook-and-loop cable wraps come in a variety of colors and sizes and can be ordered from most cable equipment and wire management suppliers.

Figure 1: Reusable cable wraps

Thursday, October 6, 2011

Optical Fiber Testers

Optical fiber requires a unique class of cable testers. Just like copper-cable testers, optical fiber testers are specialized. Figure 1 shows a simple continuity tester that verifies light transmission through the cable.

Figure 1: An optical fiber continuity tester
Another type of optical fiber test device is the power meter (also known as an attenuation tester), such as the one shown in Figure 2. Like the continuity tester, the power meter tests whether light is making its way through the cable, but it also tests how much of the light signal is being lost. Anyone installing fiber-optic cable should have a power meter. Most problems with optical fiber cables can be detected with this tool. Good optical fiber power meters can be purchased for less than $1,000.

Figure 2: An optical fiber power meter
An attenuation tester checks for how much signal is lost on the cable, whereas a continuity tester only measures whether light is passing through the cable.
Many high-end cable testers, such as those available from Hewlett-Packard, Microtest, and others, can test both optical fiber and copper cables (provided you have purchased the correct add-on modules). You need to know a few points when you purchase any type of optical fiber tester:
  • The tester should include the correct fiber connectors (ST, SC, FC, LC, MT-RJ, etc.) for the types of connectors you will be using.
  • The tester should support the type of fiber-optic cable you need to test (single-mode or multimode).
  • A power meter should test the wavelength at which you require the cable to be used (usually 850 or 1,300nm).
Professional fiber-optic cable installers usually carry tools such as an OTDR that perform more advanced tests on optical fiber cable. OTDRs are not for everyone, as they can easily cost in excess of $30,000. However, they are an excellent tool for locating faults.