Utah Code § 54-7-7
The commission, each commissioner and each officer and person employed by the commission shall have the right at any and all times to inspect the accounts, books, papers and documents of any public utility, and the commission, each commissioner and any officer of the commission or any employee authorized to administer oaths shall have power to examine under oath any officer, agent or employee of any public utility in relation to the business and affairs of said public utility; provided, that any person other than a commissioner or an officer of the commission demanding such inspection shall produce under the hand and seal of the commission that person's authority to make such inspection; and provided further, that written record of the testimony or statement so given under oath shall be made and filed with the commission.
Utah Code § 54-7-7