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Construction was called off last year on an expansion of the V.C. Summer nuclear power plant north of Columbia. File/Provided/High Flyer

South Carolina Electric & Gas says it will fight a decision that allowed state lawmakers to slash its electricity rates, sending the fight over its failed nuclear project to an appeals court in Virginia.

SCE&G announced its plans to challenge the rate reduction on Tuesday, the same day it went into effect. A day earlier, U.S. District Judge Michelle Childs decided that the power company didn't have a strong enough case to keep its rates from falling.

The legal tussle began in June, when the state Legislature voted to cut SCE&G's power rates by about 15 percent, or $22 a month for the typical home. The temporary cut, which only lasts through the end of the year, is meant to keep electricity users from paying as much for the failed expansion of the V.C. Summer nuclear power plant.

The unfinished reactors, which were being built north of Columbia, accounted for 18 percent of SCE&G's rates before the Legislature's vote, and it cost the typical home $27 a month. Lawmakers also ordered the utility to refund most of the money ratepayers put into the failed project over the last few months.

If the temporary reduction is allowed to stand, it would cost the utility about $270 million.

SCE&G didn't say what argument it would make to the Fourth Circuit Court of Appeals in Richmond, Va. In federal court in Columbia, the Cayce-based SCANA Corp. subsidiary argued that it was unfair for lawmakers to punish it for the $9 billion failure at V.C. Summer because they were changing the rules governing the project only after it went belly-up.

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Childs rejected that argument and wrote that SCE&G might not be entitled to collect anything for the project since state law only allows it to collect on reactors that are "constructed or being constructed."

Still, the state hasn't made a decision yet on who will ultimately pay for the project. The S.C. Public Service Commission, which regulates utilities, will have the final say later this year.

Reach Thad Moore at 843-937-5703. Follow him on Twitter @thadmoore.