Section 36.003 - Just And Reasonable Rates(a) The regulatory authority shall ensure that each rate an electric utility or two or more electric utilities jointly make, demand, or receive is just and reasonable.(b) A rate may not be unreasonably preferential, prejudicial, or discriminatory but must be sufficient, equitable, and consistent in application to each class of consumer.(c) An electric utility may not: (1) grant an unreasonable preference or advantage concerning rates to a person in a classification;(2) subject a person in a classification to an unreasonable prejudice or disadvantage concerning rates; or(3) establish or maintain an unreasonable difference concerning rates between localities or between classes of service.(d) In establishing an electric utility's rates, the commission may treat as a single class two or more municipalities that an electric utility serves if the commission considers that treatment to be appropriate.(e) A charge to an individual customer for retail or wholesale electric service that is less than the rate approved by the regulatory authority does not constitute an impermissible difference, preference, or advantage. Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. 9/1/1997.