Typically, crimp-on connectors are for stranded cable, and one of the biggest mistakes people make is using the wrong crimp-on end. If you look very closely, you will see a row of ‘teeth’ on the underside of the exposed pins. These teeth pierce the insulation of the cable to make electrical contact with the copper wire. Using a crimp-on connector designed for a solid cable on a stranded cable can result in an unreliable connection (and vice-versa).
Home Cabling Pt IV
Typically, crimp-on connectors are for stranded cable, and one of the biggest mistakes people make is using the wrong crimp-on end. If you look very closely, you will see a row of teeth on the underside of the exposed pins. These teeth pierce the insulation of the cable to make electrical contact with the copper wire. Using a crimp-on connector designed for a solid cable on a stranded cable can result in an unreliable connection (and vice-versa).
Brian Karas is a Senior Network Support Engineer for the leading Frame Relay equipment provider by day, and a Home Automation and DataComm consultant and installer 'the rest of the time'.
Were nearing the end of our series on planning and installing an open-standards residential wiring system. As promised, this article is intended to address the issues of terminating your cables properly, and also some tips on mounting wiring closet components for a neat appearance.
Pictured here is a typical faceplate found in a common residential cabling system. It houses 2 Cat5 cables, and 2 RG-6 cables. It provides a neat appearance and easy connection of devices to the cabling system.
Here is the same faceplate, pictured from the back. Notice that the Cat5 cables terminate directly into their RJ-45 outlets, while the RG-6 cable terminates in a standard fashion, and then connects to an F feedthru connector.
The RG-6 cables are fairly easy to handle. RG-6 is what is known as a coaxial cable, this means that there are 2 or more conductors that share a common axis or center point. In the case of a standard RG-6 the center conductor carries the signal, while the outer conductor provides a shield. While it is not difficult to terminate RG-6 cable once you know the proper procedures, it is important that you pay close attention to your work. If a stray wire from the shield makes contact with the center conductor you will experience extreme signal degradations. You must also be careful not to cut or nick the center conductor.
Before the connector can be applied the RG-6 cable must be properly stripped back. While this can be accomplished with a utility knife, a more reliable and consistent strip can be achieved with the proper tool, shown here.
The coaxial cable stripper has 2 razor blades whose heights can be independantly adjusted. The stripper is rotated around the cable to cut the outer jacket back to the proper depth. As you can see here, a properly stripped RG-6 cable actually has 3 distinct levels when stripped. The center conductor is exposed, with the shield on the next level, and then the outer jacket left on the thrid layer.
After the cable has been stripped make sure that no loose strands from the braided shield are contacting the center conductor, or hanging over the end of the 2nd layer. Once the cable is inspected, you are ready to put the connector in place, and secure it with the proper tool. There are several different styles of RG-6 connectors, some requiring different tools. They are all based on the same general idea, that the center conductor is left untouched, and the connector itself makes an electrical connection with the shield, and a mechanical connection with the cable itself to secure it in place. Two tools are pictured here:
The tool on the left is used for crimp-on connectors that can be found in most electrical stores, and home improvement type stores. The tool on the right is a Snap-N-Seal® Tool. The Snap-N-Seal® system forms a superior bond (in my opinion), resulting in a connector that is less likely to become separated from the cable. Both tool variants (and all other outlets, tools, etc) are available from http://www.futurestandard.com
After the connector is firmly seated on the cable it is secured by the proper tool, usually one good squeeze is all it takes.
The result should be a firmly seated connector, with the center conductor protruding approximately ¼" past the threaded portion of the connector.
After the RG-6 cable has been terminated, it can be attached to the appropriate feed-thru connector. Pictured here are various connectors, from left to right: A F-F feedthru for standard CATV type applications, an F-RCA feedthru for audio, video, or similar low-level signals.
The termination of Cat5 cables is an entirely different system. You begin by removing approximately 2-3" of the outer jacket. This can be accomplished by peeling the jacket back, and cutting the excess off, or by the use of a general purpose round cable jacket stripper.
As you can see in the picture above, the Cat5 cable on the right has a neater appearance due to the use of the stripper pictured.
Once the Cat5 jacket has been removed, the individual pairs need to be aligned accordingly. In many cases the color arrangement may not follow the 568A or 568B standards. This is due to the fact that most Cat5 outlets employ a design to minimize crosstalk, and thus have internal crosses that carry the wires to the proper pin. You do not however have to strip any wire from the individual wires. Cat5 connectors use an IDC, or Isulation Displacement Connector. The insulation is removed when the wire is punched-down into the connector. There are a few different styles of IDC connectors, but the two most common types are 110 and 66 style. You may hear of Bix or Krone, but these are generally only found in commercial installations, and even there they are the minority by far. 66 style connectors are generally only found on 66 blocks, shown below.
A standard Cat5 outlet will have a 110 style connector scheme. Most connectors will have the color codes on the cable to make placing the wires easier.
Place the appropriate wire in each slot, using a thumbnail or small screwdriver to seat it just so the it doesnt fall out. After all the wires are in place the connector can be punched down with an impact tool and 110 blade. As you can see, the 110 blade has two distinct sides, one will both punch the cable, and cut the excess, the other will only punch, leaving the excess cable.
Typically, you will use the cutting side of the blade. Before you punch the wires, be positive that the cutting side is facing the proper direction. As it has been noted in previous articles in this series, Cat5 cable is what is known as a twisted-pair cable. The wires are arranged in pairs that are twisted together, this twisting is a large portion of what gives Cat5 cable its performance characteristics. When aligning the wires into the outlet, be sure to try and keep the pairs as even in length as possible, and do not untwist more than ½" of cable.
Cat5 Patch panels will also typically have 110-style connectors. They are also color coded, but typically arrange the wires by pairs, as seen here.
The same general idea is applied here. Its best to terminate cables in
order, starting from Outlet #1. If your patch panel is mounted on a hinged wall rack, be
sure to route the cables so that there is enough additional cable to allow the rack to
pivot without stretching the cable, or placing any unnecessary stress on the cables. Most
patch panels will have loops for you to tie-down the cable bundles to keep the
punched-down portions from moving or flexing.
66 Blocks are common in large PBX installations, but really have no place in a residential system. They are terminated as follows:
Align the wires into the individual connectors as shown above. After the wires are aligned and dressed (routed) they are punched down with an impact tool and 66 blade, shown below. Like a 110 blade, the 66 blade will have a cut and non-cut side.
Punchdown connections are really pretty easy, once you have the proper tools, and know where the wires go. People often have problems however with RJ-45 crimp-on connections. If you design your system properly, you really shouldnt need to even own an RJ-45 crimper, but sometimes special circumstances arise that make it necessary to require an RJ-45 or RJ-11 crimp-on end.
Typically, crimp-on connectors are for stranded cable, and one of the biggest mistakes people make is using the wrong crimp-on end. If you look very closely, you will see a row of teeth on the underside of the exposed pins. These teeth pierce the insulation of the cable to make electrical contact with the copper wire. Using a crimp-on connector designed for a solid cable on a stranded cable can result in an unreliable connection (and vice-versa). Your supplier should be able to provide the proper crimp-ons for your cable type. Solid cable is difficult for a novice to crimp, stranded cable is even more difficult. The same procedures are followed in either case (save for the selection of the crimp-on end) so well use solid cable to demonstrate.
First, remove about 2" of the cable jacket, as shown here. This is where the round cable stripper mentioned earlier helps to do a neat and quick job.
Next, separate the wire pairs by fanning them out slightly.
Now, align the wire pairs into the color-coding scheme you are using in your system. Again, you want to keep the untwisted portion of the wire as short as possible, no more than ½", and preferably much less.
After the wires are aligned properly, straighten them out for easy insertion into the connector, and snip the ends of straight.
Insert the cable into the connector, paying close attention to ensure the wires fall into the appropriate slots on the connector. The ends of the wires should reach to the end of the plug.
After visually inspecting the cable, insert it into your crimper and squeeze down to finish the crimp.
Pull slightly on the connector to ensure that it is properly seated and has a good mechanical bond.
This covers the most common connector types found in residential cabling installations. If youd like to see a particular connector illustrated, send an e-mail to: firstname.lastname@example.org and Ill illustrate it in another article.
Before you can complete your residential cabling system, we also need to discuss cable routing and management techniques in the wiring closet.
Depending on the size of the system, the cables may be broken out into individual racks by type, or they may all reside on the same rack. In either case, I like to separate the cables into similar groups after they enter the wiring closet. This makes for a neater appearance for the finished project.
You can use a long screw to guide the cable bundles around a curve, and also alongside the bundle to provide a convenient zip-tie point. The cables should actually be routed up to the patch panels before any termination is done. This will ensure that they maintain a uniform length and appearance.
The RG-6 cables are organized using a modular system (available at http://www.futurestandard.com). The modular patch panel consists of a blank panel, with the appropriate inserts to configure the panel for the cable type(s). In smaller installation the modular system can save you money by only buying as many inserts as you need, and allowing you to mix Cat5 and RG-6 on the same panel.
The cable management bracket allows you to keep your patch cords neat and tidy. Velcro zip-ties are also handy for the occasional Move/Add/Change work that goes on.
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