Box Fill Conductors #6 and Smaller
Box Fill Calculations
Where a box is planned to contain conductors which are sizes #6 and smaller,
then a volume calculation will allow you to determine the correct box size for
the job. Usually this means finding the depth of a device box but it cal also
mean determining the size of a junction box.
So a #14 AWG conductor is calculated at 2 cubic inches
#12 AWG conductor 2.25 cubic inches
#10 AWG conductor 2.5 cubic inches
#8 AWG conductor 3 cubic inches
#6 AWG conductor 5 cubic inches
There are quite a few special considerations found in the NEC article
dealing with box fill. Read article NEC 314 to refresh your memory of these
Note: Remember that pull boxes for conductors sized #4 and larger are
determined based on raceway size, and not cubic inches.
Several box fill worksheets are available for practice on this topic. Click
on a page number. The image will come up on your computer screen. You can press
the print button to make a copy of the page. Click the Audio Support words to
hear a description of the technique of solution.
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