Conduit Fill Chart
A conduit fill chart compares total conductor area with raceway internal area and the applicable fill limit. The calculator keeps that chart workflow live for mixed conductor sizes.
conduit fill chart conduit fill calculator by wire size and type raceway fill worksheet
Fill formula
fill percent = 100 * total conductor area / conduit internal area
Common screening limits
- One conductor: 53 percent fill limit.
- Two conductors: 31 percent fill limit.
- Three or more: 40 percent fill limit.
Mixed sizes
For mixed conductors, sum each size group separately before dividing by conduit area. The calculator supports up to three groups.
Related pages
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- Conduit fill calculator - raceway fill from conductor count, area and conduit size.
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- Short-circuit current calculator - available fault current from transformer impedance.