Trough fill calculations

[danray35]

I have inherited someone's headache. The set up so far is 37 separate 12-2 mc home runs. I have to land them in a trough then bring them down thru emt to the panel.

I understand that I am limited to not using more than 20 percent of the raceway cross section. Furthermore I am over the maximum of 30 current carrying conductors so I will have to derate. What is confusing me is the conductor fill. If the wires are spliced, does that mean my count now goes up to 74 current carrying conductors? The trough they purchased is 6x6 by 24 inches. Who am kidding, im confused as to all of it. I wonder now how my derating is going to affect my ampacity. If someone can give me hand here I would appreciate it.
Thanks

 

[infinity]

You'll need to arrange those condcutors so that no cross section of the wireway has more than 30 CCC's. This can be done by installing several conduits to the panel and routing the conductors through them. Better choice would be a junction box where you won't have to deal with the derating issues.