There shall be exempted from the provisions of NRS 245.213, 245.214 and 245.215:
1. All department heads appointed and elected and the county administrator or county manager of the county.
2. A number of employees in each department excluding the department head as designated by the department head, which shall not exceed 3 percent of the permanently established positions as authorized by the board of county commissioners.
3. All persons holding temporary or provisional appointments, the duration of which does not exceed 6 months.