The City Administrator shall enforce strictly the provisions of the budget. He shall not authorize any payment or the incurring of any obligation by the City unless an appropriation has been made for the same and there is a sufficient unexpended balance left after deducting the total past expenditures and encumbrances against the appropriation. No officer or employee of the City shall place any order or make any purchase for a purpose not authorized in the budget resolution. Any obligation incurred by any person in the employ of the City for any purpose not authorized in the budget resolution or for any amount exceeding a department appropriation shall be a personal obligation upon the person incurring the obligation unless ratified by the City Council.