
Conduit Fill Useful Remaining SpaceThe calculation to find the unused percent is straight forward.First add up all the contained conductors in square inches.Next, determine the percentage of space that was used by dividing the used area by the total area.Lastly, subtract this percent of used area from the useful area in percent.Note that the useful area could be 40% for a raceway of no longer than 24 inches. The useful area of a nipple is 60% when the raceway is 24 inches or less in length.

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