(a) The commission, by order, may require any utility or any officer or agent thereof to produce within the state, at such reasonable time and place as it may designate, any books, records, accounts or documents kept in any office or place without or within the state, or certified copies thereof, whenever the production thereof is reasonably required and pertinent to any matter under investigation before the commission, in order that an examination thereof may be made by the commission, or by any person employed by the commission.

(b) The commission shall examine and inspect, or cause to be examined and inspected, at reasonable times and in a reasonable manner, under its authority, the books, records, accounts, documents, plant, property and facilities of any utility, whether there is any proceeding by or against the utility then pending before the commission or not. Every utility, its officers and agents shall make all its books, records, accounts and documents available at its principal office or place of business in this state, for examination and inspection by the commission or its authorized representatives or employees, whenever the commission may deem it in the public interest that such examination or inspection should be made. Every utility, its officers and agents shall make available all and every part of its plant, property and facilities for examination and inspection by the commission or its authorized representatives or employees, whenever the commission may deem it in the public interest that such examination or inspection should be made; and any person shall produce, when so required, his authority from the commission to make such examination or inspection under the seal of the commission.