Conduit Fill Calculator
Add your conductors, pick the raceway, and get the fill percentage and the smallest conduit that fits.
The rule
NEC Chapter 9, Table 1: a single conductor may fill 53% of the raceway, two conductors 31%, and three or more 40%. Areas come from Table 5 (conductors) and Table 4 (conduit). Mixed sizes are summed by area.
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