Whenever an electrical utility desires to put into operation a new rate it shall give not less than thirty days' notice of its intention to file and shall, after the expiration of the notice period, then file with the Commission a schedule setting forth the proposed changes. Copies of the schedule must also be given to other parties as the Commission may direct. Subject to the provisions of subsections (C) and (D) of Section 58-27-870, the proposed changes may not be put into effect in full or in part until approved by the Commission. Nothing contained in this section affects the existing provisions of Act 1293 of 1966.