caculating j box size

[SparkyRules]

I want to run 4-4" conduits in one side of a j-box (314.28-(A)(1)=8x largest raceway or 4"x8=32 " minimum. However out the other side I want to attach a 8" duct(Art376). would the 8" duct be considered a raceway if so then I would need 8x8 or a 64" J box? Comments?

 

[kingpb]

I assume the 4" conduits are carrying 4 sets of parallel conductors the duct you mention is actually wireway.

Therefore the MINIMUM distance from the side where the conduits enter to the opposite side with the wireway is the 32" you mention.

However, I think a question arises that the cables can only take up 20% of the cross sectional area of the wireway. Hence, 8" x 8" = 64 sqin; 20% is 12 sqin

If the 4 x 4" conduits are all filled to maximum 40%, then you have 20 sqin of conductors and the 8" x 8" wireway is not sufficient.

Something to consider.

 

[jusme123]

...a wireway is considered a raceway.


what is being pulled through the 4" conduits?

 

[kingpb]

a wireway is considered a raceway

Maybe, but according to 376.22(A) the sum of the conductors cross sectional area cannot exceed 20% of the wireway interior cross-sectional area.