Neb. Rev. Stat. §§ 14-2153
A metropolitan utilities district shall not sell any gas-burning equipment or appliances, at either retail or wholesale, if the retail price of that item exceeds fifty dollars, except that newly developed gas-burning appliances may be merchandised and sold during the period of time in which any such appliances are being introduced to the public. New models of existing appliances shall not be deemed to be newly developed appliances. A gas-burning appliance shall be considered to be in such introductory period of time until the particular type of appliance is used by twenty-five percent of all the gas customers served by such district, but such period shall in no event exceed seven years from the date of introduction by the manufacturer of the new appliance to the local market.
Neb. Rev. Stat. §§ 14-2153