Tenn. Code § 68-102-150
Every person, firm or corporation, or legal entity engaged in the business of installation of electrical wiring, heating, or any electrical devices that require inspection by this chapter and regulations adopted pursuant to this chapter, shall register with the division of fire prevention, and shall pay a fee of twenty-five dollars ($25.00); provided, that such registration and payment shall not be required of persons, firms, corporations or other legal entities engaged in such business in counties with populations of seven hundred thousand (700,000) or more, according to the 1980 federal census or any subsequent federal census, that conduct their own inspections. Application shall be made on forms provided by the commissioner of commerce and insurance, and the commissioner is empowered to adopt any reasonable rules or regulations in order to accomplish the purposes of this section.
T.C.A. § 68-102-150