Metal fabrication is the creation of metal structures by cutting, bending and assembling processes. It is a value-added process involving the creation of machines, parts, and structures from various raw materials.

Labor or material used in installing, altering, maintaining, or extending an electrical wiring system and the appurtenances, apparatus, or equipment used

plumbing, system of pipes and fixtures installed in a building for the distribution and use of potable (drinkable) water and the removal of waterborne wastes