The governing body, by a two-thirds vote of the members thereof, or where the utilities are under the control and management of a board of public utilities, said board by a three-fifths vote thereof, may contract for or make repairs, alterations, extensions, reconstructions, enlargements or improvements of any of its municipally owned utilities and issue or cause to be issued revenue bonds in payment of the cost thereof without submitting to a vote of the electors of such municipality the proposal to contract for or to make such repairs, alterations, extensions, reconstructions, enlargements or improvements and to issue such bonds in payment of the cost thereof: Provided, That such repairs, alterations, extensions or improvements will not cause duplication of existing utility service furnished by a private utility: Provided, however, That the governing body or other proper officers of any such municipality shall, before contracting for or making any such repairs, extensions, reconstructions, enlargements or improvements, cause to be published in the official paper of said municipality or, if said municipality has no official paper, then some paper of general circulation in such municipality, a notice of its intention so to do which notice shall describe the nature of the proposed repair, alteration, reconstruction, enlargement or improvement, state the total amount of the cost thereof and the amount of the bonds to be issued for the payment thereof: Provided, however, If, within fifteen days after the publication as aforesaid of such notice, there shall be filed with the clerk of such municipality a written protest against such proposed repairs, alterations, extensions, reconstructions, enlargements or improvements and such bond issue, signed by not less than twenty percent of the qualified electors of such municipality, the governing body of such municipality shall thereupon submit such proposed project and the proposed bond issue to the electors of such municipality at a special election to be called for that purpose upon at least ten days’ notice, to be held not later than sixty days after the filing of such protest or at a regular city election or general election which will occur not sooner than thirty days nor not later than sixty days after the filing of such protest. In the event that a majority of such voters voting on such proposition at such election shall vote in favor thereof, such repairs, alterations, extensions, reconstructions, enlargements or improvements shall be made and such bonds may be issued in payment of the cost thereof.