(a) This subchapter applies to a municipality located in a county any part of which is located within 57 miles of a major astronomical observatory at the McDonald Observatory.
(b) This subchapter does not apply to:
(1) outdoor lighting in existence or under construction on January 1, 2012; or
(2) the installation, maintenance, repair, or replacement of outdoor lighting owned or operated by an electric utility as defined by Section 31.002, Utilities Code.