An electrical outlet powers the broadband connection at the Manassas architect's firm.

"The greatest advantage is that we only need to have an outlet to use it," Mr. Porter said.

Manassas is the second city in the nation where broadband service over power lines became commercially available. City officials there began marketing the service in February.

Today, only about 300 U.S. consumers pay for high-speed Internet access over power lines, but this new method of delivering Web content could jolt the market for Internet service.

Allentown, Pa., and Cincinnati are the only other U.S. cities where residents are paying for the new high-speed Internet service, but electric companies from North Carolina to Hawaii are testing the service or plan to begin a pilot project. Federal regulators hope broadband access over power lines becomes widely available, especially in rural areas.

In Manassas, 60 homeowners and a handful of businesses have Internet access through power lines. Another 1,200 homeowners have asked to be hooked up. That's nearly 10 percent of the city's 12,500 homes.

By the end of the year, broadband over power lines could be available to all Manassas residents. It would be the first U.S. city where the technology is available to all residents.

Internet access from power lines began to get attention last year, when the Federal Communications Commission (FCC) promoted it as a way to offer high-speed Internet services for people in rural areas. The FCC also saw broadband access from power lines as an alternative to high-speed access from phone, cable and satellite companies that could lower consumer prices.

Because the power grid is ubiquitous, broadband over power lines could be available to nearly every U.S. home.

"Having another major player - the power companies - has to help bridge the digital divide. The power companies have the infrastructure to make broadband available nationally," said Ed Thomas, chief of the FCC's Office of Engineering and Technology.

The FCC in February proposed rules to govern broadband over power lines. The rules aren't final, but a handful of cities, utilities and technology companies are pushing forward.

Current Communications Group in Germantown, Md., is working with Ohio utility Cinergy Corp. to market broadband service over power lines in Cincinnati.

Current Communications also has a pilot project with Pepco in Potomac to test the new Internet service.

"There are a lot of utilities out there that really, really want to do this," said Jay Birnbaum, vice president of Current Communications, a privately held firm founded four years ago.

Main.net Powerline Communications in Reston is working with Manassas, which owns its electric plant, to deliver Internet content over the power lines.

Main.net and Current Communications are two of the primary companies in a small cluster of firms that market technology to send Internet data over power lines and make the modems that subscribers plug into wall sockets.

Experts long have known power lines could accommodate Internet data. Electricity travels at a lower frequency than an Internet signal, so the two can share a power line.

Public works department employees in Manassas hook up new Internet subscribers nearly every day.

"They're beating down our doors," said John Hewa, assistant director of the city's electric utility.

That's because few people there have high-speed Internet access, Mr. Hewa said.

"A lot of people are telling us they can't get high-speed services where they live. There are a lot of areas where it's not available, and they're using dial-up service," he said.

The FCC found in June 2003 that there were no high-speed Internet subscribers in 9 percent of U.S. zip codes, where about 1 percent of residents live. In another 16 percent of U.S. zip codes, there was just one broadband provider.

The American Public Power Association, which represents utilities, says 75 percent of its members serve communities with fewer than 10,000 people, many of whom don't have high-speed Internet access.

About 24 million people subscribe to broadband service, according to Washington research firm Precursor Group.

But spokesmen for Verizon Communications Corp. and Comcast Corp. both say they are equipped to deliver high-speed service in Manassas.

The new broadband service in Manassas also might be popular because the city charges $26.95 a month, less than digital subscriber lines (DSL) or cable Internet providers. Current Communications charges a basic rate of $29.95 a month in Cincinnati. Customers typically pay $30 to $40 a month for DSL service and $40 to $50 a month for Internet access over cable.

Although the FCC is hopeful that broadband over power lines helps lower prices and provides access to underserved areas, Precursor Group analyst Pat Brogan isn't so sure the service will take off because DSL and cable Internet services have been around for years. Broadband over power lines simply might be too late to catch up, he said.

But electric companies want to make money off their power lines, and consumers who have been relegated to using low-speed dial-up services are interested in subscribing to broadband access over power lines, said Joseph Marsilii, president and chief executive of Main.net.

"I firmly believe there is a huge market for this," he said. "I think we're on the cusp."