If underground construction is necessary to provide utility service within the area affected by any ordinance enacted pursuant to this Article, the supplying utility shall furnish that portion of the conduits, conductors and associated equipment required to be furnished by it under its applicable rules, regulations and tariffs on file with the Public Utilities Commission. Underground construction by the utility shall be accomplished in accordance with the rules and regulations authorized by the Public Utilities Commission, and shall be completed within the time for removal of overhead facilities specified in the ordinance enacted pursuant to this Article.