Del. Code tit. 26, § 313

The Commission may, after hearing, by order in writing, require every public utility to carry a reasonable and adequate depreciation account in accordance with such rules, regulations, orders and forms of account as the Commission may prescribe. The Commission may, from time to time, ascertain and determine, and by order fix, the proper and adequate rates of depreciation of the several classes of property of each public utility or class of public utilities. Each public utility shall conform its depreciation accounts to the rates so ascertained, determined and fixed.