(a) This section does not apply to the retail services of an electing company, as defined by the Public Utility Regulatory Act (PURA) §58.002, or to the retail nonbasic services offered by a transitioning company, as defined by PURA §65.002.
(b) Emergency power requirements.
  (1) Each dominant certificated telecommunications utility's (DCTU) central office not equipped with permanently installed standby generators must contain adequate provisions for emergency power, including four hours of battery reserve without voltage falling below the level required for proper operation of all equipment.
  (2) In central offices without installed emergency power facilities, there must be a mobile power unit available that can be delivered and connected on short notice.
  (3) As applicable, each DCTU must comply with the backup power obligations prescribed by federal law or other applicable regulations, including the requirements of 47 Code of Federal Regulations §9.20.
(c) In exchanges exceeding 5,000 lines, a permanent auxiliary power unit must be installed.

Source Note: The provisions of this §26.52 adopted to be effective May 15, 2000, 25 TexReg 4319; amended to be effective April 7, 2014, 39 TexReg 2499; amended to be effective December 21, 2023, 48 TexReg 7524