The Public Utility Commission or the Commissioner of Public Service, the Directors for Public Advocacy and Regulated Utility Planning, and other employees of the Department authorized by the Commissioner may, during business hours, enter the offices, plants, exchanges, and stations or upon the land or lines of any company subject to supervision by the Department. (Amended 1959, No. 329 (Adj. Sess.), § 39(b), eff. March 1, 1961; 1979, No. 204 (Adj. Sess.), § 15, eff. Feb. 1, 1981.)