Tenn. Code Ann. § 8-30-310

When an emergency occurs, affecting the ability to fill a position in the preferred service under any other provision of this part, an appointing authority, in order to prevent stoppage of public business or loss or serious inconvenience to the public, may appoint any qualified person to such position with the approval of the commissioner. Any such person shall be employed only during such emergency and for a period not exceeding one hundred twenty (120) days. No such appointment shall be renewed.