Sec. 19. Every public utility shall carry a separate, proper and adequate depreciation account whenever the commission, after investigation, shall determine that such depreciation account reasonably can be required. The commission, from time to time, shall ascertain and determine the proper and adequate rates of depreciation of the several classes of property of each public utility. The rates, tolls and charges shall be such as will provide the amounts required over and above the reasonable and necessary operating expenses, to maintain such property in an operating state of efficiency corresponding to the progress of the industry. Each public utility shall conform its depreciation accounts to such rates, so ascertained and determined by the commission. The commission shall make changes in such rates of depreciation, from time to time, as it may find necessary.
Formerly: Acts 1913, c.76, s.22; Acts 1925, c.64, s.1.