South Carolina Electric & Gas Co. his asking regulators for permission to pull the plug on a billing practice that has confused many of its power customers.

The move follows a recent recommendation from a state consumer advocacy agency that SCE&G discontinue its “Weather Normalization Adjustment” that the company has used since August 2010 to calculate monthly charges.

The S.C. Office of Regulatory Staff said a month ago that the method is overly complicated and unpredictable. It also said that neither it nor SCE&G’s service representatives can explain how the billing system works, triggering complaints from customers.

“Multiple customers have expressed concerns over the lack of transparency and understandability of the WNA and, consequently, a lack of public acceptance,” the ORS said in a report on the issue. The report also noted that there’s “no stability or predictability in the rates.”

The billing method is based on 15-year average temperatures. It was designed to reduce weather-driven volatility in customer bills.

Cayce-based SCE&G said last month it would address the ORS’s recommendations.

On Tuesday, the utility filed petition with the Public Service Commission to discontinue the practice. The ORS, the American Association of Retired People and a residential customer from the Midlands also are named in the filing.

“The intent of implementing the Weather Normalization Adjustment mechanism was to provide relief to customers in periods of extreme fluctuations in weather,” said Keller Kissam, president of SCE&G’s retail operations. “Since that time the ... mechanism has collectively reduced customers’ electric bills. However, in response to the concerns of consumers and the ... Office of Regulatory Staff, we have decided to request an order ... to end the ... program.”

The change would take affect in January if approved.

More than 500,000 residential and commercial customers would be affected.

Contact John McDermott at 937-5572.