(a) Until the date on which an electric utility subject to this subchapter is authorized by the commission under Section 39.503(f) to implement retail customer choice, the rates of the utility are subject to regulation under Chapter 36.
(b) Until the date on which an electric utility subject to this subchapter implements customer choice, the provisions of this chapter, other than this subchapter and Sections 39.1516 and 39.905, do not apply to that utility.