Nothing in this chapter shall be deemed to apply to the installation, use, maintenance, alteration or repair of gas piping, gas fitting work, gas fitting system, gas appliances and gas venting by any person, who has previously installed natural gas for industrial use and performs its work through its trained regularly employed journeymen, provided that such person shall comply with all laws, rules and regulations in regard to proper gas installation. (Ord. 353, 6-10-1987)