C-1G Pipes and Vents for Gas Contractor

C-1 Plumbing and Heating Contractor

C-1A Boilers

C-1C Pipe and Duct Insulation

C-21G Industrial Piping

C-38 Gas Equipment Contractor

C-21 Refrigeration and Air Conditioning Contractor

C-21A Refrigeration Contractor

C-21B Air Conditioning Contractor

C-21C Sheet Metal Contractor

C-21D Refrigeration and Air Conditioning Maintenance Contractor

C-21F Chilled and Hot Water Systems

C-13 Sheet Metal Contractor

C-1I Chilled-Water Piping

C-1K Industrial Piping

C-1E Sheet Metal

C-1F Heating, Cooling and Circulating Air Contractor

C-2D