The Commission, either upon complaint or on its own motion, may suspend the enforcement of any or all of the proposed rates, tolls, charges, rules or regulations for schedules required to be filed under § 56-236 of any public utility, except an investor-owned electric public utility, for a period not exceeding 150 days, or if the public utility is an investor-owned water utility not subject to Chapter 10.2:1 (§ 56-265.13:1 et seq.) for a period not exceeding 180 days, from the date of filing, and the Commission shall suspend the enforcement of all of the proposed rates, tolls, charges, rules or regulations of an investor-owned electric public utility until the Commission’s final order in the proceeding, during which times the Commission shall investigate the reasonableness or justice of such proposed rates, tolls, charges, rules and regulations and thereupon fix and order substituted therefor such rates, tolls, charges, rules and regulations as shall be just and reasonable. The Commission’s final order in such a proceeding involving an investor-owned electric public utility that is filed after January 1, 2010, shall be entered not more than nine months after the date of filing, at which time the suspension period shall expire, and any revisions in rates or credits so ordered shall take effect not more than 60 days after the date of the order. Notice of the suspension of any such proposed rate, toll, charge, rule or regulation shall be given by the Commission to the public utility, prior to the expiration of the 30 days’ notice to the Commission and the public heretofore provided for. If the proceeding has not been concluded and an order made at the expiration of the suspension period, after notice to the Commission by the public utility making the filing, the proposed rates, tolls, charges, rules or regulations shall go into effect. Where increased rates, tolls or charges are thus made effective, the Commission shall, by order, require the public utility to furnish a bond, to be approved by the Commission, to refund any amounts ordered by the Commission, to keep accurate accounts in detail of all amounts received by reason of such increase, and upon completion of the hearing and decision, to order such public utility to refund, with interest at a rate set by the Commission, the portion of such increased rates, tolls or charges by its decision found not justified. The Commission shall prescribe all necessary rules and regulations to effectuate the purposes of this section on or before September 1, 1980. This section shall not apply to proceedings conducted pursuant to § 56-245 or 56-249.6.