Mich. Comp. Laws § 29.5k

Sec. 5k. In addition to the requirements specified in section 5j, each attended terminal at which a tank filled by a pipeline is located shall comply with the following requirements: (a) The high level alarm system at the terminal shall provide an audible sound of sufficient decibels to alert personnel responsible for taking corrective action. (b) The high level alarm system at the terminal shall be electrically self-supervised and equipped with an audible trouble alarm which has a distinctive sound that is not used for any other purpose. The audible trouble alarm shall sound upon the occurrence of any of the following: (i) A loss of the main electrical operating power. (ii) An electrical break or ground fault in the alarm initiating circuit or the signaling device circuit. (iii) The derangement of the high level alarm system control equipment. (iv) The removal of initiating devices. (v) The electrical derangement of the signaling devices.