Charlotte, N.C. — Duke Energy on Monday filed a request with the North Carolina Utilities Commission to increase electric rates by an average of 9.7 percent, or about $446 million.

Residential rates would go up 11.8 percent under the proposal, which would raise the monthly bill for a customer who uses 1,000 kilowatt-hours from $102.72 to $116.99.

The request calls for commercial rates to increase by 9.6 percent and industrial rates by 5.3 percent.

"Even with the proposed increase, Duke Energy Carolinas' rates would remain well below the national average," Paul Newton, who oversees Duke's North Carolina operations, said in a statement.

Newton said capital spending is driving the request, noting that Duke has spent almost $2.2 billion to build or modernize power generation plants in the Carolinas.

"As part of our ongoing fleet-modernization plan, we have recently built and put into service two new state-of-the art power plants that will provide cleaner air and serve our customers reliably for decades to come," he said.

North Carolina Attorney General Roy Cooper is fighting a 7.2 percent rate increase that the Utilities Commission awarded to Duke a year ago, saying that the agency should have placed more weight on the recession's impact on consumers in reaching its decision. The state Supreme Court hasn't yet ruled on Cooper's challenge.

Progress Energy, which Duke acquired in July, has asked the Utilities Commission for an average rate increase of 12 percent.