A group suing SC Electric & Gas thinks ratepayers may be paying more than 18%.

The Public Service Commission approved the last request for a 2.7% increase Oct. 26, 2016, bringing the charge to 18%.

This led to the highest electric rates in the US.

“How that figure presented by the Office of Regulatory Staff has been calculated has not been demonstrated and is suspect,” said Tom Clements of Friends of the Earth said.

Others have calculated that the nuclear surcharge is higher than 30%.

The documents were obtained through legal discovery by Friends of the Earth and the Sierra Club.

The two charge SCE&G executives were imprudent in allowing unchecked billions in cost overruns.

“SCE&G essentially stonewalled the discovery requests,” Clements said.

Discovery came after Bob Guild, the groups’ lawyer, filed a “motion to compel” compliance with the PSC.