The city commission shall allow the variance where a literal application or enforcement of the applicable code or regulation would result in practical difficulty or unnecessary hardship, and the relief granted would not be contrary to the public interest but would do substantial justice. In granting any variance under this chapter, the city commission may impose any reasonable conditions upon the exercise of the variance, and shall place a time limit upon the variance. In appropriate cases, the time limit may be indefinite or until revoked by the appropriate authority. (Ord. 1413-92 § 2, 1992: Ord. 1097-78 § 4, 1978: prior code § 2-1.16).