Wiring residences for work and play

Q: I am building our home in Florida and want the builder to do all the prewiring in a way that will get both the cable company and the dish TV signals. I'll have a cable TV connection right away and am not setting up a dish immediately (just for future use), but want the prewiring now so that the dish contractor won't have to drill holes through my walls later. Also, I have asked for a cable surge-protection system, which may sit at the entry point and would prevent surges from cable and satellite TV signals. I would really appreciate it if you'd let me know how all the above could be done during the home construction process.

A: Congratulations on building your new home. Your concern seems focused only on receiving entertainment video. So, I will address that first.

Cabling for broadband

Seventy-five-ohm (Ω) coaxial cabling is used for satellite, community antenna television (CATV), and closed-circuit television (CCTV) systems. But not all 75-½ coaxial cabling is the same. As with most things, better quality will cost more. In this case, however, not significantly more.

For broadband video systems (satellite and CATV), use Series 6 with aluminum foil and aluminum braid shields to properly shield the broadband signals, a copper-clad steel center conductor or bare copper center conductor surrounded by expanded foam for outlet cables, and Series 6, 11, or hard-line trunk for backbone cable (depending on the length of the run).

You should require that the CATV system outlet cables meet SCTE IPS-SP-001 June 13, 1996, Flexible RF Coaxial Drop Cable specified up to 1,000 MHz, and that the satellite system outlet cables meet SCTE IPS-SP-001 specified up to 2,200 MHz.

Baseband video systems (CCTV) commonly use coaxial cables with a 95% copper braid to properly shield the baseband signal and a bare copper center conductor typically surrounded by an expanded foam dielectric. Regardless of what the builder's subcontractor tries to tell you, Series 59 cable should only be used for baseband CCTV systems or for patch and equipment cords.

But requiring excellent cable is useless if the installer overbends, overpulls, and stretches or deforms the cable when installing it. So, how much is too much?

The minimum bend radius should not exceed 20 times the cable diameter during the pulling, and 10 times the cable diameter once the cable is placed and terminated. The maximum pulling tension of coaxial is dependent on the size and material of the center conductor. For Series 6, the pulling tension should not exceed 40 lbf (178 N).

While perfectly spaced cable clips look "neat and tidy," we are not looking for tidy inside the wall studs. To avoid degrading structural return loss (SRL) performance, have the installer vary the distance between the cable clips. Also have the installer leave at least eight inches of slack at the outlet for future testing and retermination.

Now that we have addressed your specific question, there are some additional systems for you to consider that can also require cabling:

• Security;
• Video monitoring (e.g., nanny cameras);
• Intercom systems (at exterior doors, gates, and room-to-room);
• Telephone;
• Home office networking;
• Home theater;
• Whole-house audio distribution;
• Lighting control;
• Home automation.

My, how times have changed

For many years, wiring homes changed very little. The typical setup included wiring for 120-volt convenience outlets, with a telephone jack or two and a twin-lead from the rooftop antenna or a coaxial cable from the cable-company box outside to the television.

How times have changed. Today, we are seeing homes that tend to have all the same systems as commercial buildings but without the usual wireways, cable trays, and suspended ceilings used to support the cabling in a commercial environment. This is why it is very important to prewire new homes to not only meet current needs but also provide future flexibility and expandability.

I strongly believe that houses should be constructed with pathways within the walls to allow for upgrading the low-voltage cabling. The cabling will have to be changed to accommodate new technologies, but the pathway will last for the life of the structure.

The tricky part will be making certain that you place outlets where you will need them in the future. Most home-appliance manufacturers are touting Internet-capable kitchen appliances. I have seen, and played with, several prototypes at trade shows. An outlet box with a flexible conduit back to your "network operations center" may some day contain the cabling that connects your refrigerator to "recipe central" for a report of what you can make for dinner based on the items currently in the freezer. But you would not have to gamble today on which cable to install. You could even wait until after you purchase the "smart fridge" and install the cable recommended by the manufacturer.

Don't want to see a bunch of blank outlet covers? I suggest you take pictures after the pathway is placed and before the gypsum board is hung. It is a good idea to show a measuring tape in the picture extending from either a corner or door opening. The gypsum board is hung over the box. When needed, measure over and up to locate and cut-in the outlet. This is similar to an after-set floor monument in a commercial floor distribution system.

The ANSI/TIA/EIA-570B Residential Telecommunications Infrastructure Standard addresses two grades of residential cabling, but zero grades of residential pathways. But Carlon (www.carlon.com), a manufacturer of thermoplastic enclosures, fittings, and wire- and cable-management products, has done an excellent job in a publication entitled Carlon Structured Cable Management Systems.

The company presents a sort of good-better-best scenario for residential pathways. At a minimum, install an empty vertical chase consisting of one or more two-inch flexible conduits from the distribution-box area into the attic. For moderate coverage, add one flexible conduit run to every outlet where you think you may want to upgrade your cable in the future to the vertical chase. For maximum coverage, add one flexible conduit run to every outlet to the vertical chase.

Remember, there is little worse than having to pothole through fresh paint, expensive wallpaper, and gypsum board to run just one more cable. So, why not lighten up on the contents (cables) and concentrate on the container?

While not everyone is looking for a $100,000 home-theater or motorized drapes in every room, you should at least consider the following:

• Hinge-switches on pantry and closet doors. Open the door and the light comes on.
• A distributed audio system with cabling for speakers, here, there, and everywhere. The speakers can be added over time as it suddenly occurs to you, "Wouldn't it be great to have some music in here?" My house has speakers in every room, even the laundry room and garage.
• A control system that integrates HVAC, security, and lighting controls in one system. This allows "scenes" to be programmed. Imagine one touch of the "goodnight" button arms the alarm system, turns off the lights in the house, and sets the bathroom light at 7% as a night light.
• Add telephone and/or Web access to the control system and there is no need to wonder if you armed the security system or closed the garage door.

And for additional thought-provoking ideas, I suggest you read: Residential Network Cabling-2002, written by BICSI and published by McGraw-Hill, and ANSI/TIA/EIA-570-B-2003 Residential Telecommunications Infrastructure Standard. Also, visit Custom Electronic Design & Installation Association (CEDIA; www.cedia.net) and click on "homeowner."