A. After August 28, 1969, extensions of electric distribution lines on applicants' owned and leased properties, and in industrial parks, necessary to furnish permanent electric service to new commercial and industrial buildings, and to new multiple-occupancy buildings shall be made underground.
B. These regulations do not apply to extensions of lines of nominal 33,000 volts and higher.
C. The application of these regulations is not mandatory for extensions of lines to provide electric service to customers whose premises are so unesthetic that the construction of underground lines would serve no purpose. Customers of this nature might include gravel pits and other mining operations, junk yards, railroad yards, and steel mills.