You must install:
  (1) Individual electric (plug-in or hardwire) or battery-operated carbon monoxide detectors that meet Underwriters Laboratories Inc. requirements (UL-Listed); or
  (2) An electronic carbon monoxide detection system connected to an electronic alarm/smoke detection system that is UL-Listed.

Source Note: The provisions of this §746.5533 adopted to be effective January 1, 2004, 28 TexReg 11354; transferred effective March 9, 2018, as published in the Texas Register February 16, 2018, 43 TexReg 909