Nevada Power Co. of Las Vegas and Sierra Pacific Power Co. of Reno are pressing for changes in a rule that lets them charge competitors for past investments and contracts that have turned into bad deals.
After power industry deregulation, the ''past-cost'' rule would let the utilities charge competitors a surcharge to compensate for the investments. The Public Utilities Commission will determine the amount.
Regulators are focusing on long-term contracts signed by the utilities to get wholesale power from independently owned power plants. Those contracts specify prices that now exceed the cost of wholesale power on the market, and therefore could be designated a past cost.
A 12-member interim legislative body in April asked the PUC to review the rule because of complaints from the electric utilities, saying the utilities need better guidelines.
At a hearing Friday, Anne-Marie Bellard, a PUC staff economist, said the 90 days allowed by the Legislative Commission wasn't long enough to determine the method for calculating past costs.
Commissioner Judy Sheldrew asked about a proposed rule change that would let the utilities retain gains from power plant sales for up to three years - rather than using the gains to reduce past cost surcharges to competitors.
''I guess that's the worst case scenario,'' Bellard said.