Wireway or junction box classification question

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Tonuch

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First I would like to thank the community for participating in this forum I use it all the time but this is my first tome posting a question. I have an installation with a 42 circuit panel over top of which I have mounted a 24”long by 12” wide by 12” deep trough(wireway or junction box) , coming out of bottom of trough are three 2” conduits that are 22” long and enter the the top of the panel. I have 38 12/2 mc cables coming into top of trough (for a total of 76 ccc) and travel through the trough unbroken into the panel. The ahj is citing a violation, in that if we exceed 30 ccc in a wireway we must derate. My question is “what is the difference between a wireway and a junction box and if there are different requirements for junction boxes as opposed to wireways in regard to derating in a installation like mine”
 
Are there more than 30 CCC's at any one cross section of the wireway?

Welcome to the forum. :)
 
I am a little confused as to what cross section means. Does it mean a group of conductors crossing or coming into contact with another group of conductors? The conductors In This application come In The top in mc cable and pass straight through the trough/junction box and into 2” emt which then enter the panelboarc. Ooh and yes more then 30 ccc
 
The cross-sectional area of an object when viewed from a particular angle is the total area of the orthographic projection of the object from that angle.*

(Wikipedia)

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What version of the NEC are you on? The 2011 NEC does not mention cross sectional area, and derating would be applied if you had over 30 conductors in the wireway. "Cross sectional" was added back into the 2014 and 2017 NEC.
 
For the number of conductors in the cross sectional area of a wireway, you visualize a cut though the wireway perpendicular to the long dimension and count the number of conductors that would be cut.

In your case, I believe you have a pull box and not a wireway. There is not a clear distinction in the code for the difference between a wireway and a pull or junction box, where enclosure is used as it is in this thread.

There is a "loophole" for your issue. Take a look at the exception to 310.15(A)(2). In most applications like this, that exception will permit you to use the conductors at their normal ampacity without having to use the effects of an ampacity adjustment.
310.15(B)(2) ... Exception: Where different ampacities apply to portions of a circuit, the higher ampacity shall be permitted to be used if the total portion(s) of the circuit with lower ampacity does not exceed the lesser of 3.0 m (10 ft) or 10 percent of the total circuit.
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Some inspection authorities do not let you apply that exception because of the language in 376.22(B) that requires adjustment per 310.15(B)(3)(a), however they are not correct. The adjustment factors change the ampacity of the conductors and 310.15(A)(2) Exception applies to the ampacity of the conductors, no matter how that ampacity was arrived at.
 
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