According to officials of the utility, the typical Ameren residential customer using 10,000 kilowatt-hours of electricity a year will save about $100, or 8 percent, on the price of electricity.
Ameren officials attributed the reduction to a decline in the wholesale cost of electricity due to reduced demand.
However, officials of the Citizens Utility Board say the drop in electric rates announced by Ameren and previously by ComEd was also due to a new power-purchasing system.
Through the Illinois Power Agency, power generators submit sealed bids to sell power in the state. Through the agency, a price for power is negotiated.