Wired Wires
There are a few options for cabling to transmit smart-home signals and data. Given the possibility of merging the data network with "dumb" components, such as a home stereo, choosing the right cabling is important. This is an especially crucial decision during new home construction and extensive remodeling. Remember: It takes a fat pipe to stream DVD.
The first option is to transmit data via traditional power lines using the X-10 protocol. Every appliance requires power lines, and you can send X-10 signals across these lines if the appliances are X-10-aware. Bidirectional communication between X-10 devices is possible but very slow. Data rates of power lines vary depending on protocol, line quality and whom you ask. X-10 runs at 60 bps. Another specification, the HomePlug 1.0 standard, claims to support up to 14 Mbps. Of course, the actual rate depends on the line quality. Many household power lines aren't very clean, and interference from devices such as dishwashers can degrade performance severely.
Another option is coaxial cable, traditionally used for video signals and some data transfer -- remember thin-net and 10Base-2? Coax is simple to tap, extend and terminate. However, like power lines, coax does not have a very high bandwidth -- 10Base-2 runs at only 10 Mbps.
A third option is telephone lines. More than a decade ago, Macintosh users networked their computers with phone cables and Phonenet receivers. These simple networks may have been some of the earliest implementations of a converged data and voice network in the home. Phonenet did not work in houses with two phone numbers, however, because it ran on the unused pairs in a single-line house; newer technologies have circumvented this limitation. Using phone lines is a simple option, offering sufficient speed for limited in-house networking. However, as any Phonenet user will tell you, phone-line networking is painfully slow, especially for file transfers. The Home Phoneline Networking Alliance 1.0 standard ran at 1 Mbps, and the current 2.0 standard is at 10 Mbps.
A fourth option is to use Category 5E cable, which can provide transmissions up to gigabit speeds -- more than sufficient for video and data. Linksys recently has come out with an eight-port gigabit switch for only $189. Full-motion video uses a lot of bandwidth because, while dropouts and high compression are acceptable in Web video and videoconferences, such disturbances are not acceptable while watching a DVD, especially during action scenes that involve explosions. DV (digital video) streams, such as those from a consumer DV camcorder, run at 25 Mbps without audio; audio and time-code data raise this to approximately 36 Mbps. A 50-Mbps DV format that yields higher quality also is available. Current DVD players support a maximum bit rate of 9.8 Mbps for just the video and have limited room left for audio, which may push DVD standards to require more bandwidth.
Another high-bandwidth application, HDTV, is still quite complex for consumers -- and for broadcasters. Figuring out HDTV, which has 36 video formats, is about as difficult as building a functional space station from Lego parts. HDTV needs approximately 18 Mbps under compression for action and sports events. An uncompressed HDTV stream uses a whopping 1.2 Gbps.
In the digital space, less compression yields better quality, and in the coming years consumers may demand even sharper images, higher resolutions and more sound channels (such as 7.1 audio as opposed to 5.1 or traditional stereo). As with any network, it's important to future-proof your design and make sure enough bandwidth will be available for unforeseen applications.
Cat 5E cabling is available in plenum and nonplenum forms. Plenum cabling has a special coating designed to release fewer fumes when melting; in fact, some local fire codes may require plenum cabling. There are no real data-performance differences, but plenum cabling costs much more than nonplenum per foot -- as much as three times the cost in some cases. And some have found plenum more difficult to work with and install because it is less flexible.
Currently, the last wired option is fiber. However, most vendors we consulted said fiber wasn't necessary for the home. Fiber is more expensive than the other cable options, harder to pull and more complex to terminate. The price for 1,000 feet of bulk Cat 5E (PVC) from Data Comm Warehouse is $99.99; plenum, $279.99; two-wire PVC fiber, $329.99; and two-wire plenum fiber, $349.99.
Of course, there also are wireless options, but the bandwidth just isn't there yet for high-quality video using the 802.11b wireless standard. Wireless should be sufficient for audio and some file transfers. Remember that DVD requires more than 9.8 Mbps, and 802.11b has a theoretical maximum transmission rate of 11 Mbps. Although it may be the mode of delivery in the future, wireless is struggling to get 54 Mbps using 802.11a. In comparison, Cat 5E transmits at gigabit speeds. Wireless also has interference problems, and security issues as passersby can pick up broadcasts.
Our choice? Cat 5E for a high-speed data-based network. You can run low power levels over Cat 5E, too, so devices like corded telephones, thermostats and VoIP phones don't require an additional power outlet. Automation and other very low-bandwidth applications are easy and inexpensive to implement over power lines. Some theorize that copper and wireless will co-exist eventually (rather than being mutually exclusive), but the fact is that high-bandwidth applications, such as video and fast file sharing, are best run over copper, at least for the next few years.
Home Director (which was spun off from IBM) and other vendors selling structured-wiring systems are targeting new constructions, rather than older house retrofits. Cat 5E cable is very simple to install during home construction. All connections should homerun to a central location. Home Director estimates that in California this could cost about $1,400 for four outlets. Although this estimate seems a little high to us, the cost depends greatly on the house style, length of runs, construction location and contractor.
If you're building a new home, consider installing Cat 5E cable for telephone lines instead of traditional Cat 1 through Cat 3. It'll be easier to upgrade from voice to a data or VoIP network if Cat 5E cable is in place.
A wonderful idea for new installations is to install conduit tubing, as is often done in office buildings. Conduit and pull lines let you easily add new lines or replace cabling later on. In a few years, you may want to replace the Cat 5E with fiber or wire a previously unwired room. In-place conduit tubing eliminates the expense and headache of the "blindly fishing wires through the wall" method of remodeling. The cost of conduit can vary depending on type (PVC versus metal), local codes, contractors and size of runs. It is not unreasonable to expect conduit to add $5,000 to the cost of a project. Do-it-yourselfers take note: The wiring is pulled through the conduit after the drywall is put up.
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