Revenue certificates; terms; price and interest; three-fifths vote of governing body required.

(1) Any municipality which acquires, constructs or extends any of the public utilities authorized by this chapter and desires to raise money for such purpose, may issue mortgage revenue certificates or debentures therefor without regard to the limitations of municipal indebtedness as prescribed by any statute now in effect or hereafter enacted; provided, however, that such mortgage revenue certificates or debentures shall not impose any tax liability upon any real or personal property in such municipality nor constitute a debt against the municipality issuing the same, but shall be a lien only against or upon the property and revenues of such utility, including a franchise setting forth the terms upon which, in the event of foreclosure, the purchaser may operate the same, which said franchise shall in no event extend for a period longer than 30 years from the date of the sale of such utility and franchise under foreclosure proceedings.

(2) Such mortgage revenue certificates or debentures shall be sold for at least 95 percent of par value and shall bear interest not to exceed 7.5 percent per annum.

(3) No mortgage revenue certificates or debentures shall be issued except upon a three-fifths affirmative vote of the city council, or other legislative body of the municipalities by whatever name known; such mortgage revenue certificates or debentures shall provide that out of the revenues and income derived and obtained from the operation of the utility so constructed, such portion thereof as may be deemed sufficient after all operating costs have been paid, shall be set aside annually in a sinking fund for the payment of interest on said certificates or debentures and the principal thereof at the maturity of the same.