Tenn. Code Ann. § 2-9-111

The governing body of a city, town or county may adopt voting machines and, upon the adoption and purchase of voting machines, shall provide for payment for the machines in the way it deems for the best interest of the locality and may for that purpose issue bonds, certificates of indebtedness or other obligations which shall be a charge on the city, town or county. Such bonds, certificates or other obligations may be issued with or without interest, payable at such time or times as the authorities may determine, but shall not be issued or sold at less than par. If it is proposed that bonds be issued to finance the purchase of voting machines, such bonds may not be issued unless approved in an election by a majority of the votes cast by the voters of the city, town or county affected.