Florida Power & Light Co. filed a proposal with state regulators Tuesday to build a 300-mile natural gas pipeline in eastern Florida.

The pipeline, dubbed the Florida EnergySecure Line, would extend from Palm Beach County in southern Florida to Bradford County in the northern part of the state. The pipeline could enter service as early as 2014, Florida Power & Light said.

Florida Power & Light is the utility subsidiary of Juno Beach, Fla.-based FPL Group (FPL).

The Florida EnergySecure Line would be the third major natural gas pipeline in the state. Natural gas supplies to the other two, the Florida Gas Transmission Co. and Gulfstream Natural Gas pipeline systems, were increased significantly in 2008 with the construction of the Southeast Supply Header pipeline.

That pipeline, a joint venture between Spectra Energy (SE) and Centerpoint Energy Inc. (CNP), extends 270 miles from the Perryville Hub in northern Louisiana to interconnections with the two Florida pipelines in southern Alabama.

The Florida EnergySecure line would use existing rights-of-way associated with utilities, roads or railroads for about 90% of its length, Florida Power & Light said.

Florida Power & Light, the largest electric utility in Florida, serves 4.5 million customer accounts in the state.

-By Christine Buurma, Dow Jones Newswires; 201-938-2061; christine.buurma@dowjones.com