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Home Automation Consultant "In the absence of wiring guidelines, some homeowners started installing ad hoc networks. One the first applications was do-it-yourself cable TV extensions. Typically, homeowners purchased the cheapest cable and connectors sold. Likewise, telephone extensions were installed with poor quality wires." |
Dr.
Kenneth Wacks provides management and engineering consulting in home and building
automation to utilities and manufacturers world-wide. He offers impartial and practical
advice on business opportunities, network alternatives, and product development. The EIA
(Electronic Industries Alliance) has appointed him chair of the committee establishing
international home and building automation standards. He is the author of "Home
Automation and Utility Customer Services," published by Cutter
Information Corp. For further information, please contact Ken at: |
The Wiring Chaos
Home owners and installers seeking information about wiring networks to support home theater, home office, and home automation are confused because there are no guidelines or standards. Builders follow local, state, or provincial codes that mandate safe installation of 120 and 240-volt electrical wiring. In the United States, telephone wiring is the responsibility of the Federal Communications Commission (FCC). However, the FCC depended on the Bell System to standardize telephone wiring. Since divestiture of the AT&T operating companies in 1984, there have been no commonly established wiring practices.Many new homes are wired barely adequately for telephone services. For example, some homeowners are finding no spare wires for extra phone lines. Much of the phone wire is poor quality, resulting in cross-talk between voice and data signals on adjacent lines.
The buzz in the home automation industry this year has been home networks. This reflects the recognition by the personal computer (PC) industry that there are business opportunities in linking home PCs. This makes home PCs targets for sales of network cards and network software. Some PC companies would like to expand such networks to serve appliances, thus becoming home automation networks. Ultimately, there is likely to be competition between PC companies and consumer electronics companies for a stake in the home appliance market.
Home Wiring Options
In the absence of wiring guidelines, some homeowners started installing ad hoc networks. One the first applications was do-it-yourself cable TV extensions. Typically, homeowners purchased the cheapest cable and connectors sold. Likewise, telephone extensions were installed with poor quality wires.
In the past few years, suppliers of wiring products have started to introduce wiring packages that address the home market. The top-of-the-line packages include:
- Two quad-shielded RG-6 coaxial cables
- Four or eight twisted-pair wires, category 5
Poor-quality coaxial cable has a single foil shield or a dual shield of foil and some braiding (densely packed wire strands). Most coaxial cable that is homeowner-installed is RG-59. This has a smaller diameter than RG-6, and hence large losses per foot of cable.
It is important to understand that high quality wiring requires high quality connectors and outlets all along the signal path. Poorly grounded coaxial cable connectors can cause noise and ghosts on TVs. The challenge with coax distribution of TV signals is to maintain signal strength and fidelity while keeping out unwanted broadcast signals.
The latter is called ingress in the cable industry. Signal leakage from a
cable, or egress, not only may result in a snowy picture, but might interfere with
aircraft navigation. The FCC has the authority to order cable companies to disconnect
customers with wiring that radiates, especially in the VHF aircraft band (about 108-135
MHz).
The August issue of HTINews included
a comprehensive survey of structured cabling manufacturers. Most offer a package of
coaxial cables, twisted-pair wires, distribution panels, and outlets. 
The typical twisted-pair wires are category 5, as designated by the
Telecommunications Industry Association (a sector of the EIA, the Electronic Industries
Alliance, based in Washington, D.C.). Category 5 wires can carry a bandwidth of up to 100
MHz, as contrasted with POTS wires (Plain Old Telephone System), which support 3 kHz.
(Category 2 is rated at 1 MHz, category 3 is 16 MHz, and category 4 supports 20 MHz.)
Wiring Standards
There are no standards yet. However, the
Telecommunications Industries Association (TIA) is in the final stages of writing a U.S.
standard for residential wiring (TIA-570-A). 
The specification has been balloted and comments submitted with the votes are
being resolved, as is common practice in standards development. A similar wiring standard,
T525, is under development by the Canadian Standards Association.
The preliminary version of TIA-570-A introduces a grading system based on the services expected to be supported in a house or apartment. Grade 1 provides a generic cabling system that meets the minimum requirements for telecommunications services. As an example, this grade provides for telephone, satellite, cable TV, and data services. Grade 1 is roughly equivalent to existing telecommunications cabling in many residences, but includes the evolution to twisted-pair cable and the placement of the cable in a star topology. To meet the proposed TIA standard, Grade 1 twisted-pair wiring must be category 3 or better. However, category 5 is recommended. One coaxial cable network is also required.
Grade 2 provides a generic cabling system that meets the requirements for basic, advanced, and multimedia telecommunications services. This grade provides for both current and developing telecommunications services. Grade 2 twisted-pair wiring stipulates category 5 quality and one or two coaxial cables. Fiber optic cabling to each location is optional.
A joint committee of the ISO/IEC (International Organization for
Standardization and the International Electrotechnical Commission) is working on a
comprehensive world wiring standard for homes, buildings, and SOHO (small office, home
office) to support all services beyond power. 
This work is a collaborative effort of two working
groups: Home Electronic System, which I chair, and Customer Premises Cabling,
which deals with building wiring. (The Home Electronic System standard was
described in the April issue of HTINews.) The international wiring standard is
being edited for committee review and ballot by the member nations next year.
The international standard under development will include requirements similar to the TIA. The wiring systems in the international standard will specify a command and control network for home and building automation, cabling for information technology communications, and wiring for home electronics.
Promoting Structured Wiring
The Home Automation Association (HAA) is
launching a campaign called Wire Americas' Homes to promote the use of structured wiring. 
As the logo indicates, the HAA
intends to influence wiring practices throughout the western hemisphere. The campaign is
directed toward builders and homeowners. The recommended complement of wiring includes
four twisted pairs of category 5 wire plus two quad-shielded coaxial cables.
Standards and recommended practices are voluntary in the U.S. Hopefully, builders and installers will adopt wiring standards and practices because they benefit homeowners. Furthermore, properties should become more valuable when marketing them as equipped with home networks that comply with national and international standards.
© Copyright 1998, Kenneth P. Wacks
