The Iowa Utilities Board is investigating the way Cedar Rapids-based Alliant Energy purchases electricity. Board spokesman Rob Hillesland says they want to be sure the costs passed along to customers for the purchase of electricity are legal. Hillesland says electric companies can pass some costs on to customers through what’s called the “energy cost adjustment” or E-A-C.Hillesland says the Utilities Board has asked for a complete review of Alliant’s electric purchases in the past year as they ask for an increase in the E-A-C.Hillesland says the board wants to review the information to see if Alliant’s been following the rules under the E-A-C.Alliant has until May 15th to supply the information to the Utilities Board. Alliant serves 380-thousand electricity customers in Iowa.