The provisions of this section shall be applicable to officers of political subdivisions, including, but not limited to, cities, towns, villages, townships and counties, as well as school, fire, power and drainage districts not included in Section 29-3-15. Such officers, subject to such regulations as the executive head of the political subdivision may issue, shall, upon approval of this chapter, designate by title (if feasible) or by named person, emergency interim successors and specify their order of succession. Such executive head shall review and revise, as necessary, designations made pursuant to this chapter to insure their current status. Such executive head shall designate a sufficient number of persons so that there will be three deputies or emergency interim successors or any combination thereof at any time. In the event that any officer of any political subdivision or his deputy provided for pursuant to law is unavailable, the powers of the office shall be exercised and duties shall be discharged by his designated emergency interim successors in the order specified. The emergency interim successors shall exercise the powers and discharge the duties of the office to which designated until such time as a vacancy which may exist shall be filled in accordance with the Constitution or statutes or until the officer or his deputy or a preceding emergency interim successor again becomes available to exercise the powers and discharge the duties of his office.