For three or more wires, the total wire area cannot exceed 40% of the conduit’s internal cross-sectional area.
Beyond simple fill calculations, several factors influence the choice of conduit size: conduit sizes
Multiply the area of one wire by the number of wires you plan to pull. For three or more wires, the total wire
Conduit size is determined by the number and gauge of wires it must contain. This is governed by the National Electrical Code (NEC) Chapter 9. For three or more wires