The Wired Home: Part 10 of 12

The Wired Home: Part 10 of 12

You've put in the time and effort to carefully route your cabling behind the wall. Don't screw it up with a shoddy finishing job It may be true that you can't judge a book by its cover, but when it comes to the physical appearance of the visible portions of a structured wiring system, aesthetics can be a deciding factor in how the installation is perceived. You may have paid close attention to routing

You've put in the time and effort to carefully route your cabling behind the wall. Don't screw it up with a shoddy finishing job

It may be true that you can't judge a book by its cover, but when it comes to the physical appearance of the visible portions of a structured wiring system, aesthetics can be a deciding factor in how the installation is perceived. You may have paid close attention to routing the cabling in the wall cavity — which, it should be noted, the homeowner will never see — but a sloppy finishing job on things like terminations and faceplates will be the only tangible representation of your work. The proper trim-out, organization, and connection of the associated cables and terminations will not only help the system run smoothly but also give it the professional appearance desired by homeowners.

This 10th installment in a 12-part series of articles meant to prepare electrical contractors to take the test to be certified as home technology integrators (HTI), will address the trim-out phase of the project, which includes all the different ways the medium should be terminated, before exploring how to connect the subsystems to the structured media center after all the terminations have been completed.

Trim cables and install outlets.

The trim-out phase of a structured media installation includes termination of cables, connection of subsystems in the distribution panel, and testing to ensure connectivity. The tools and equipment you'll need to complete this phase of the job include the following:

  • Labels for the cabling

  • Wire snips or wire cutters

  • Cat. 5 UTP stripper

  • Impact/punchdown tool with 110-bit and blade

  • RG-6 quad-shield coax stripper

  • RG-6 quad-shield coax F-connector/crimper

  • Six- and eight-position telephone and Cat. 5 plug crimp tool

  • Multimeter or volt-ohm meter

  • Cat. 5 tester

  • Modular plug breakout adapter

  • Tone test set

  • Inductive probe

When terminating twisted-pair cables, take care to minimize the amount of untwist on the wires; it's essential that you have no more than 0.5 in. of untwist on the individual pairs. In fact, less is better. You can follow either the T568A or T568B wiring patterns, but only the former complies with the ANSI/TIA/EIA-570-A standard. If two jacks are installed in a single faceplate, each jack should be supplied by its own four-pair cable. If it's an RJ-45 jack, you must ensure that the outer jacket of the cable is captured by the small strain relief tab that's located inside the plug.

When terminating Cat. 5 cable, you should follow the recommendations outlined in the EIA/TIA-568-A standard. This standard defines line configuration when terminating cable and determines the order in which the wires should be placed in the connectors. Strip only as much cable jacket as required and take care to not untwist the wires or accidentally nick the insulation. Removing the cable jacket properly and terminating it securely ensures that every wire connection is made with full contact between the wire end and its termination point.

A wire punchdown/termination tool will press wire conductors into place and trim the wire in insulation displacement connectors (IDCs) and in QuickPort modular snap-in jacks. Push the tool's handle to engage one of its five interchangeable blades, which will terminate 22-, 24-, or 26-gauge solid wire into 110-style IDC punchdown blocks.

EIA/TIA-570 standards recommend that you use eight-conductor jacks only with a T568A/B wiring pattern on the outlet end.

Each twisted-pair of conductors within a Cat. 5 cable is color-coded to correspond with the color-coding on the termination jack and the distribution module. And each pair is twisted at a different twist rate than the other pairs in the cable or bundle to give the cable greater immunity to interference.

Terminate each twisted-pair on its own color-coded location on the eight positions of a Cat. 5 jack. The color combination identifies the pair number (1 through 4) as well as the tip and ring wire within the pair. The Table (right) shows the wiring color codes standard for Cat. 5 cable.

You should terminate Cat. 5 cable in a Cat. 5 jack with 110 IDC connectors per the T568A wiring pattern. Use the same care as with the punch down process mentioned earlier. EIA/TIA-570 recommends the use of eight-conductor Cat. 5-compliant jacks only. Using the specialized tools discussed earlier, strip and punch down the jack. Adhere to the T568A/B wiring pattern and follow the color code as shown on the jack.

Follow this six-step procedure when attaching the RJ-45 connectors to a Cat. 5 cable.

  • Strip back 2 in. of sheathing from the cable.

  • Untwist the pairs and flatten and arrange them in the proper color-code order.

  • Trim the wires to 0.5 in. from the sheathing.

  • Insert the wires into the RJ-45 connector.

  • Make sure that each wire slides under the crimping ”teeth” in the connector and is far enough inside the connector to be crimped.

  • Crimp the connector using an RJ-45 ratchet-style crimper. Use a punchdown tool for all receptacles.

It's highly recommended that you perform Cat. 5 certification testing, also known as compliance testing, to verify your cable installation has been installed properly. Test all wiring for continuity, attenuation, crosstalk, and cable quality.

Audio cables.

Audio cables are specified and selected based on their size, or wire gauge. They're usually two-stranded conductors, 16-gauge or larger, and they aren't uniformly color-coded. Because one conductor in an audio cable can typically be distinguished from the other by markings or raised ridges on the insulation, special attention should be paid to polarity. In some instances, the conductor itself may have a different color. For instance, one may have a copper color, whereas the other has a silver color. You may even find the insulation on the conductors to be colored differently.

Audio cables are most commonly terminated on screw terminals or binding posts. First, split the insulation of the audio cable about 1 in. from its end. Then strip 0.5 in. of insulation from each individual strand of wire. Next, wrap the exposed wire around the screw terminal or binding post in a clockwise direction and tighten the set screw. Never wrap the wire more than 180∞ around the screw, as you may break the strands as you tighten the screw.

Coaxial cables.

Kinks and tight bends can change the impedance or introduce loss into a coaxial cable. Therefore, you must handle it with care. Use a special stripping tool to prepare coaxial cable for termination. The tool is equipped with two blades — one slits the outer jacket only, while the other slits the inner jacket, the braid, and a portion of the center dielectric insulation. Note that single-braid and quad-shield cables require different connectors.

The recommended terminations for video wiring are compression lock or threaded male F-type connector. First, use a high-quality stripping tool to strip back about 0.75 in. of the cables outer jacket, 0.5 in. of the center conductor, and approximately 0.25 in. of the braiding and foil. Next, separate the outer braid from the white dielectric insulation and raise it so it will fit within the outer channel of the F connector. Slide the F connector over the cable so the dielectric fits within the center channel of the connector and flush with the back of the F connector. The outer braid should fit within the outer channel of the connector. The center conductor should protrude 0.25 in. from the F connector. Then, crimp the connector in place. Trim the center conductor at a 45° angle so it protrudes between 0.0625 in. and 0.25 in. from the end of the connector.

During the rough-in stage of the project, you ran speaker wire to the appropriate locations in the home. Now it's time to connect the source devices to these cable runs. First, connect the audio devices to the control amplifier and the system receiver. Then connect the audio output interfaces to a connecting block. Finally, terminate all speaker wire runs to the connecting block.

Follow the same general process when connecting the video components of the system. First, connect source devices to the modulator. Then connect the modulator to the coaxial wall jack that sends the video signals to the distribution panel. Finish by connecting the television to the coaxial wall jack.

Making connections at the structured media center.

All RG-6-type cables that enter the structured media center (SMC) should reach about halfway down the distribution panel box. All Cat. 5 cables should come close to touching the bottom of the distribution panel box. Cables that enter the distribution panel should be grouped together by type with Velcro. The configuration of the SMC should provide openings for each of the groupings of cables, such as Cat. 5 and coax.

The modules installed in the SMC are dependant upon the requirements of the home network and may include a computer module, entertainment module, telephone module, or home automation control module. These modules simply need to be installed in the preset spaces provided. Use divider plates, tray guides, and cable combs as necessary to ensure an orderly installation. Items that require power, such as hubs, switches, gateways, amplifiers, and modulators, should be given special consideration.

In many applications, 110-style IDC termination hardware is used. These terminations should follow the standard color code (white/blue, white/orange, white/green, and white/brown) of the T568A wiring scheme mentioned earlier. Most 110-type terminations for home networking use are fabricated on printed circuit boards. The printed circuit board creates the T568A wiring scheme for the different services provided through the termination panel.

The cables are typically routed through the middle pathway of the 110 blocks from either the bottom or the top, and fanned into the wireway from alternate sides. Contact is assured by punching down over the frame. The type of application determines the connecting block pair.

In the SMC, a patch panel or punchdown block allows organized phone wiring terminations. The patch panel can reside in the main distribution panel or it can be wall-mounted. It's typically designed to facilitate future changes to the home phone network.

A typical home networking design generally calls for the security system to be connected to other systems, like the phone and automation control systems (Figure). For instance, the phone system is used to notify the security-monitoring service that the alarm, smoke detector, or carbon monoxide detector has detected an emergency situation in the home. For this reason, you must run the phone line through the security unit in the distribution panel.

Terminating the cable for a home automation control system is similar to terminating the wires for a light switch. X-10, the standard for home automation control (HAC), can limit what a device can do based on its termination. For instance, incandescent light fixtures can be controlled in an X-10 system because the filament in the light bulb provides a path for X-10 signals to flow. Unfortunately, low-voltage and fluorescent lamps can't take advantage of X-10 control.

The last step for the cable installation is to run cross-connects or patch cords. The patch cord delivers the actual services to the user outlets. It's common for voice outlets to use silver satin patch cords, whereas data patch cords will be constructed of Cat. 5 or Cat. 5e type cable. It's much easier to manage the installation of the distribution device if you use different color or style patch cords to differentiate between voice and data systems.

The patch panel constitutes the central wiring node of the home data network or LAN. For the computer network, use Cat. 5-rated patch panels at a minimum to ensure high-speed data transmission. When the cables terminate on one side of the patch panel, use cross-connects to connect the terminated cables to a series of RJ-45 connectors on the other side of the patch panel.

Like any piece of electrical equipment, the AC power module should be installed per all appropriate electrical codes. The SMC should be wired to a dedicated 15A circuit using 14/2 or 12/2 Romex. Don't use a power strip in place of the power module because it will void the UL Listing of the distribution panel.

Install the power supply to the left of the junction box on the bottom ledge of the enclosure so the AC power cord comes out from the right of the power supply and the DC power cord comes out from the left. Use the clamps provided with the SMC to route the DC power cord for the power supply behind each tray you install. Maintain at least a 0.25-in. space from any other cables. Connect the incoming power cable to the surge suppressor receptacles. An appropriate ground wire should be secured between the grounding lug and an earth grounding point.

After putting days' worth of work into neatly and properly installing components of a system that the end-user will never see, it seems almost criminal to take short cuts on the few portions that they will see. Putting forth the extra effort to do it the right way will yield a system that not only the user will appreciate but that you can be proud of.

Dusthimer is publisher of Cisco Learning Institute, York, Pa.

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