Some Manhattan residents may soon be able to get high-speed Internet access from everyday electrical sockets. The Federal Communications Commission approved new rules last week allowing increased use of the power line technology. Consolidated Edison plans to begin testing the technology in a high-rise apartment building on the Upper West Side in the next several months. The utility decided to expand its use of the technology after a successful pilot program in Westchester County that began in July 2002 and cost $480,000, Con Ed officials said. While the technology is several years from being ready for widespread use, experts and regulators say it has potential.