Conduit Fill Percent

Conduit Fill Percent

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Conduit Fill

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Conduit Fill Percent

Conduit fill percent is always a comparison of the installed conductors to the total space in the raceway. Do not make a percent comparison of the installed conductors to the useful space. This is not correct. But there is more confusion about this comparison than there needs to be.

Again, to determine the conduit fill percent, use the area of the installed conductors divided by the total area of the entire raceway.

Fill percentage can not exceed 60% for a nipple of 24 inches or less in length, and fill can not exceed 40% for a raceway with three or more conductors.

Calculator technique

Find the area of each of the installed conductors in square inches. Add them together.

Find the total area of the raceway from the table in Chapter 9. Divide the conductor area by the area of the raceway. The result will be the percent used by the installed conductors.

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