Each officer of the City, or of any department or board thereof, whether elected or appointed as a substitute for a regular officer, shall be an elector of the City, except as otherwise expressly provided, and before entering upon his official duties shall tax an oath to support the Constitution of the United States and the Constitution of Ohio, and an oath that he will faithfully, honestly and impartially discharge the duties of his office.  Such provisions as to official oaths shall extend to deputies, but they need not be electors.
(ORC 733.68)