Arizona regulators have launched an inquiry into the rates and profits of the state's largest electric utility following a rate challenge and customer complaints.
The Arizona Republic reports the Arizona Corporation Commission voted unanimously Tuesday to file a new case on Arizona Public Service Co. rates.
The commission approved a rate hike for the utility in 2017, with officials saying the increase averaged about 4.5%, or $6 a month for residential customers.
Customers have disputed those figures, saying their bills increased more.
Rate cases typically take about a year to resolve and proceed like court trials.
The rate cases include expert testimony and a review of the utility's spending.