(a) If the valuation of the property of any utility has become final as provided in this article, or if such valuation becomes final as provided in Section 37-4-18, the commission may, within 90 days after any valuation hereafter made becomes final, proceed for reasons which it shall deem sufficient to make a revaluation of the property of such utility of which a valuation has been made or may be made under the provisions of this chapter, such revaluation being had upon the principles declared in this chapter; and the commission may to this end make such further investigation as provided in this chapter as it may see fit. The commission shall give notice to any utility of its intention to proceed to a revaluation of the property of such utility.

(b) Whenever the commission shall have completed its revaluation, it shall make a report thereof, and before such revaluation shall become final, the commission shall give notice to such utility, and to each municipality in which it renders service as shown by the records of the commission, stating the valuation placed upon the property so revalued, and shall allow 60 days in which such utility, or any person who uses the service of such utility, or any municipality in which such utility operates, may file a protest of the same with the commission. If no protest is filed within 60 days, the valuation fixed in such report of revaluation shall become final, as of the date thereof. If notice of protest is filed by any utility whose property is so revalued, or by any person who uses the service of such utility or any municipality in which such utility operates, the commission shall fix a time for hearing the same and shall proceed as promptly as practicable to hear and consider any matter relative and material thereto which may be presented in support of any such protest so filed. If, after hearing any such protest, the commission shall be of the opinion that the valuation fixed in its report of revaluation should not be made final, it shall make such changes as may be necessary to do justice, and shall issue an order making such valuation as corrected, final as of the date thereof, which order shall be a final order of the commission. If, after hearing any such protest, the commission shall be of the opinion that the valuation fixed in its report of revaluation should be made final, it shall issue an order making such valuation final as of the date thereof, which order shall likewise be a final order of the commission. Any such final order and the commission's report of revaluation upon which the same is based shall be a permanent public record of the commission, and shall be kept on file at its office. If no protest is filed as provided in this article, and the valuation fixed by the commission in its report of revaluation becomes final, as herein provided, then the valuation fixed in such report of revaluation shall for all future rate-making purposes be the permanent basic valuation of the property of such utility. If protest is filed as provided in this article, and after hearing thereof, and order thereon, no appeal is taken to the Circuit Court of Montgomery County, then the valuation fixed by such final order on the commission's report of revaluation shall for all future rate-making purposes be the permanent basic valuation of the property of such utility.

(c) In the case of any revaluation in a proceeding in which the final order of valuation is made, the cost of services of engineers, accountants or other experts employed and used by the commission in such revaluation proceeding shall be borne by the commission where such revaluation is by the commission on its own motion, or upon the application of some person other than the utility whose property is involved.