SAN DIEGO, July 20 -- A Sempra Communications, a unit of Sempra Energy, said it has developed technology to connect thousands of miles of underused high-speed fiber optic cable to buildings across the US by inserting the cable directly into existing natural gas pipelines. Sempra said using its utility's gas lines -- which hook up to buildings in cities throughout central and southern California -- could tackle the telecommunications industry's problem connecting end users to outlying fiber optic cable networks without tearing up city streets. Sempra Communications' technology encases fiber optic cable in a protective polyethylene conduit before inserting it through the same pipelines that carry gas to utility customers, saving time and leaving neighborhood streets intact.