Ind. Code § 8-1-2-22
All money thus provided shall be set aside out of the earnings and carried in a separate depreciation fund. The money in this fund shall be applied first to depreciation expenses. Any balance in the fund, not applied to depreciation expenses, may be invested by the public utility or expended temporarily by it for new construction, extensions or additions to its utility property. This fund shall be used for no other purpose. If invested, the income from the investment shall be carried into and become a part of the depreciation fund. Any balance, not applied to depreciation expenses, shall always remain a part of the depreciation fund. In no event shall moneys, temporarily expended from this fund for new construction, extensions or additions to the property, be carried into or considered a part of the capital account of such public utility. Upon the sale of any public utility property, to continue in operation as such, the balance in the depreciation fund, unexpended for depreciation expenses, shall be transferred to the purchaser and by the purchaser shall be held, administered and used as herein authorized and required.
IC 8-1-2-22