(2) The officer shall thereupon ascertain and prescribe as near as can conveniently be done an electric current rate or rates for the ensuing year which will create a fund sufficient to meet all requirements in subsection (1) of this section.
(3) The officer may also include a further amount sufficient to create such fund, as in the judgment of the officer may be desirable or necessary to meet requirements of future contemplated additions, improvements or extensions to the plant or system.