(a) General rule.--Unless the commission otherwise orders, no public utility shall make any change in any existing and duly established rate, except after 60 days notice to the commission, which notice shall plainly state the changes proposed to be made in the rates then in force, and the time when the changed rates will go into effect. The public utility shall also give such notice of the proposed changes to other interested persons as the commission in its discretion may direct. Such notices regarding the proposed changes which are provided to the utility's customers shall be in plain understandable language as the commission shall prescribe. All proposed changes shall be shown by filing new tariffs, or supplements to existing tariffs filed and in force at the time. The commission, for good cause shown, may allow changes in rates, without requiring the 60 days notice, under such conditions as it may prescribe.
(b) Hearing and suspension of rate change.--Whenever there is filed with the commission by any public utility any tariff stating a new rate, the commission may, either upon complaint or upon its own motion, upon reasonable notice, enter upon a hearing concerning the lawfulness of such rate, and pending such hearing and the decision thereon, the commission, upon filing with such tariff and delivering to the public utility affected thereby a statement in writing of its reasons therefor, may, at any time before it becomes effective, suspend the operation of such rate for a period not longer than six months from the time such rate would otherwise become effective, and an additional period of not more than three months pending such decision. The rate in force when the tariff stating the new rate was filed shall continue in force during the period of suspension, unless the commission shall establish a temporary rate as authorized in section 1310 (relating to temporary rates). The commission shall consider the effect of such suspension in finally determining and prescribing the rates to be thereafter charged and collected by such public utility. This subsection shall not apply to any tariff stating a new rate which constitutes a general rate increase as defined in subsection (d).
(c) Determination.--If, after such hearing, the commission finds any such rate to be unjust or unreasonable, or in anywise in violation of law, the commission shall determine the just and reasonable rate to be charged or applied by the public utility for the service in question, and shall fix the same by order to be served upon the public utility and such rate shall thereafter be observed until changed as provided by this part.
(d) General rate increases.--Whenever there is filed with the commission by any public utility described in paragraph (1)(i), (ii), (vi) or (vii) of the definition of "public utility" in section 102 (relating to definitions), and such other public utility as the commission may by rule or regulation direct, any tariff stating a new rate which constitutes a general rate increase, the commission shall promptly enter into an investigation and analysis of said tariff filing and may by order setting forth its reasons therefor, upon complaint or upon its own motion, upon reasonable notice, enter upon a hearing concerning the lawfulness of such rate, and the commission may, at any time by vote of a majority of the members of the commission serving in accordance with law, permit such tariff to become effective, except that absent such order such tariff shall be suspended for a period not to exceed seven months from the time such rate would otherwise become effective. Before the expiration of such seven-month period, a majority of the members of the commission serving in accordance with law, acting unanimously, shall make a final decision and order, setting forth its reasons therefor, granting or denying, in whole or in part, the general rate increase requested. If, however, such an order has not been made at the expiration of such seven-month period, the proposed general rate increase shall go into effect at the end of such period, but the commission may by order require the interested public utility to refund, in accordance with section 1312 (relating to refunds), to the persons in whose behalf such amounts were paid, such portion of such increased rates as by its decision shall be found not justified, plus interest, which shall be the average rate of interest specified for residential mortgage lending by the Secretary of Banking in accordance with the act of January 30, 1974 (P.L.13, No.6), referred to as the Loan Interest and Protection Law, during the period or periods for which the commission orders refunds. The rate in force when the tariff stating such new rate was filed shall continue in force during the period of suspension unless the commission shall grant extraordinary rate relief as prescribed in subsection (e). The commission shall consider the effect of such suspension in finally determining and prescribing the rates to be thereafter charged and collected by such public utility, except that the commission shall have no authority to prescribe, determine or fix, at any time during the pendency of a general rate increase proceeding or prior to a final determination of a general rate increase request, temporary rates as provided in section 1310, which rates may provide retroactive increases through recoupment. As used in this part general rate increase means a tariff filing which affects more than 5% of the customers and amounts to in excess of 3% of the total gross annual intrastate operating revenues of the public utility. If the public utility furnishes two or more types of service, the foregoing percentages shall be determined only on the basis of the customers receiving, and the revenues derived from, the type of service to which the tariff filing pertains.
(d.1) Multiple filings prohibited.--Except as required to implement an order granting extraordinary rate relief, no public utility which has filed a general rate increase request pursuant to this section shall file an additional general rate increase request pursuant to this section for the same type of service until the commission has made a final decision and order on the prior general rate increase request or until the expiration of the maximum period of suspension of the prior general rate increase request pursuant to this section, whichever is earlier.
(e) Extraordinary rate relief.--Upon petition to the commission at the time of filing of a rate request or at any time during the pendency of proceedings on such rate request, any public utility may seek extraordinary rate relief of such portion of the total rate relief requested as can be shown to be immediately necessary for the maintenance of financial stability in order to enable the utility to continue providing normal services to its customers, avoid reductions in its normal maintenance programs, avoid substantially reducing its employment, and which will provide no more than the rate of return on the utility's common equity established by the commission in consideration of the utility's preceding rate filing, except that no utility shall file, either with a request for a general rate increase or at any time during the pendency of such a request, more than one petition under this subsection pertaining to rates for a particular type of service, nor any supplement or amendment thereto, except when permitted to do so by order of the commission. Any public utility requesting extraordinary rate relief shall file with the petition sufficient additional testimony and exhibits which will permit the commission to make appropriate findings on the petition. The public utility shall give notice of the petition in the same manner as its filing upon which this petition is based. The commission shall within 30 days from the date of the filing of a petition for extraordinary rate relief, and after hearing for the purpose of cross-examination of the testimony and exhibits of the public utility, and the presentation of such other evidentiary testimony as the commission may by rule prescribe, by order setting forth its reasons therefor, grant or deny, in whole or in part, the extraordinary relief requested. Absent such order, the petition shall be deemed to have been denied. Rates established pursuant to extraordinary rate relief shall not be deemed to be temporary rates within the meaning of that term as it is used in section 1310.
(f) Limitation on rate increases by certain public utilities.--Whenever there is filed with the commission any tariff stating a new rate based in whole or in part on the cost of constructing an electric generating unit, the commission shall compare the estimated construction cost filed in accordance with section 515(a) (relating to construction cost of electric generating units) with the actual construction cost submitted by the utility in support of that tariff. If the actual construction cost exceeds the estimated construction cost, the rate determined by the commission under this section shall not be based on any part of that excess unless the public utility proves that part of the excess to have been necessary and proper. In making its determination under this subsection, the commission shall consider all relevant and material evidence, including evidence obtained pursuant to section 515. For purposes of this subsection "construction" includes any work performed on an electric generating unit which required, or is expected to require, the affected public utility to incur an aggregate of at least $100,000,000 of expenses which, in accordance with generally accepted accounting principles, are capital expenses and not operating or maintenance expenses.