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All public utilities to which an order of the Commission applies shall make such changes in their schedules on file as may be necessary to make the same conform to said order, and no change shall thereafter be made by any public utility in any such rates, tolls, or charges, or in any joint rate or rates, without the approval of the Commission, except as provided in section 24 of this title. Certified copies of all other orders of the Commission shall be delivered to the public utility affected thereby in like manner, and the same shall take effect within such reasonable time thereafter as the Commission shall prescribe.