No bonds shall be issued unless approved by three-fifths of the electors voting thereon at any general or special election; provided that the foregoing shall not apply to bonds issued in anticipation of the collection of taxes actually levied and uncollected or for which an appropriation has been made; special assessment bonds, whether solely an obligation of the special assessment district or both an obligation of the special assessment district and a general obligation of the City; bonds for the City's portion of local improvements; refunding bonds; emergency bonds, as defined in Act No. 279, Public Acts of 1909, as amended; and any other bonds which by law are not required to be approved by the electors.