Any municipality which owns or operates any system, shall have the power and authority through its utilities commission to borrow money and issue its negotiable notes or certificates of indebtedness therefor, in an amount not to exceed ten percent (10%) of the gross revenues of the system in the last preceding fiscal year, in any calendar year, for the purpose of improving, repairing or extending any such system, or of stockpiling fuel for any such system, or systems, without the necessity of calling and holding an election upon such question or otherwise obtaining the consent of the qualified electors of the municipality, or giving any notice thereof. However, the utilities commission shall secure approval of the governing authorities of the municipality. In all cases where money is borrowed under the provisions of this section, the same shall be repaid within three (3) years and at no time shall the amount of money borrowed under this section exceed thirty percent (30%) of the gross revenues of the system for the last preceding fiscal year.