Mississippi Public Service Commission officials have opened an inquiry into how fuel adjustment charges tacked onto electricity bills are calculated by the state’s utilities.

Specifically, the three-member commission will look into “carrying charges” figured into the adjustments added to usage bills that reflect the price of natural gas used at generating plants.

A fourth-quarter fuel adjustment that took effect this month reduced residential bills for Entergy Mississippi customers by $10.50 per 1,000 kilowatt hours, a second decrease of a July adjustment that spiked bills by 28 percent. Natural gas prices on the commodity markets were cited by the company in both instances.

Findings by the PSC since the first increase have shown that, under the current system, utilities are allowed to place the charges on under and over collections, according to a Tuesday release from the commission.

The charges act as interest rates within the fuel adjustment, Central District Commissioner Lynn Posey said.

Currently, the charges equal 12.83 percent for Entergy Mississippi, which serves 45 counties including Warren, and 13.25 percent for Mississippi Power, which serves 23 counties, mainly in south Mississippi.

Later this month, the PSC expects a report to be completed by utility expert Walter Drabinski of Cudjoe Key, Fla.

Drabinski was hired by the commission in July at the outset of its investigation into fuel adjustment clauses.

A hearing is set for Dec. 2 to gather public comment on a proposed move to require utilities to provide live, non-automated customer service on their respective consumer hotlines.

Commissioners include Posey, the panel’s vice-chairman, Southern District Commissioner Chairman Leonard Bentz, the chairman, and Northern District Commissioner Brandon Presley.