.-(1) [* * *][The Board shall provide each year for depreciation such sum calculated in accordance with such principles as the Central Government may, after consultation with the Authority, by notification in the Official Gazette, lay down from time to time.

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(3)

[ The provisions of this section shall apply to the charging of depreciation of the year in which the Electricity (Supply) Amendment Act, 1978 (23 of 1978), comes into force.] [Substituted by Act 23 of 1978, Section 15, for Section 68 (w.e.f. 3.6.1978). ] [Substituted by Act 23 of 1978, Section 15, for Section 68 (w.e.f. 3.6.1978). ]