Tennessee Code Title 5. Counties § 5-17-103

(a) The county-wide fire department shall be headed by an official to be known as the county fire chief, in whom shall be vested all the powers of the agency and the right to delegate those powers to such persons as the fire chief may see fit.

(b) While responding to, operating at, or returning from an emergency site, the fire chief, or any member serving in the capacity of fire officer in charge, shall have all authority granted to municipal fire departments by § 6-21-703.

(c) The county fire chief shall be appointed by the county mayor, subject to confirmation by the county legislative body or other governing body.

(d) In counties governed by a metropolitan government as defined by § 7-1-101, this section shall not be effective, and the management and control of the agency or department shall be vested in the person in whom the charter of the metropolitan government vests the management and control of the agency that has the responsibility for the protection against fire of life and property within the urban services district.

(e) In any county having a population of not less than eight hundred thousand (800,000), according to the 2000 federal census or any subsequent federal census, the county fire chief shall be appointed by the county mayor, subject to confirmation by the county legislative body. The county mayor and legislative body shall ensure that the views and opinions of all participating governmental entities are given full consideration in the selection of the fire chief, with the exact methodology to be determined by local ordinance.