RALEIGH— Duke Energy and Progress Energy said Monday they’ll spend $110 million to build new power transmission lines or enhance existing ones in a third bid to get approval from federal regulators for a merger creating the largest U.S. electric utility.

The Federal Energy Regulatory Commission twice last year said the companies did not do enough to protect competition in their North Carolina and South Carolina home markets.

Duke Energy and Progress Energy last month told North Carolina regulators they’re willing to spend up to $150 million to reduce competition concerns. The utilities now say they will launch seven projects to increase the electricity that can flow into the states from outside suppliers.

“We’re essentially expanding the ability to bring in energy from outside resources such that wholesale customers within this region can have access to the outside resources,” Progress Energy spokesman Mike Hughes said.

If approved, the combined company would serve 7.1 million customers in North Carolina, South Carolina, Florida, Indiana, Ohio and Kentucky.

• Emery P. Delasio, Associated Press