How Do You Size A PVC Electrical Conduit?
Mike Holt, National Electric Code (NEC) consultant to Electrical Construction & Maintenance (EC&M) Journal, says, “Rigid PVC conduit…provides many of the advantages of rigid metal conduit, while allowing for installation in areas that are wet and corrosive. This type of conduit is commonly used as an underground raceway (conduit) because of its low cost, ease of installation, and resistance to corrosion and decay.” Polyvinyl chloride (PVC) conduit doesn’t require expensive tools like a hydraulic bender and power threader to work with, so it’s the ideal conduit for the home handy person to work with. Calculate the size and number of conductors and their insulation class to be installed in the conduit and whether the PVC conduit is graded as a “Schedule 40” or as a “Schedule 80” conduit. Turn to Annex C of the NEC and select Table C9 or C10 for PVC Schedule 80 and 40 respectively. For this tutorial, assume Schedule 80 conduit with twenty AWG 10 copper conductors with THHN insulation. U
