Subject to the applicable provisions of state law and this charter, the Council, by proper ordinance or resolution, may authorize the borrowing of money for any purpose within the scope of the powers vested in the city or permitted by the present or future Constitution and laws of the state, and the issuance of bonds of the city or other evidences or indebtedness therefor, and may pledge the full faith, credit, and resources of the city for the payment of the obligation created therefor; provided, however that nothing herein shall authorize the Council to issue without an authorizing vote of the electors any bonds which by state law require such a vote. The net bonded indebtedness shall not at any time exceed 10 per cent of the assessed value of real and personal property in the city, provided that in computing such net bonded indebtedness there shall be excluded emergency loans, bonds issued in anticipation of the payment of special assessments even though they are also a general obligation of the city, mortgage bonds secured only by mortgage on the property or franchise of a public utility, other bonds which are not a lien upon the taxing power of the city, and bonds issued to refund money advanced or paid on special assessments for watermain extensions.