# of conductors in a box
Two coworkers of mine have told me that somewhere in the code book is a maximum number of conductors permitted in any size box. I have failed to find this. Article 314.16 covers box fill and nowhere in it is there a maxim number of conductors allowed no matter how large of a box you install. Article 310.15 (B)(2)(a) lists 41 or more current carrying conductors to be derated at 35%. This is in raceways however, not boxes. Article 100 does not define a raceway as a box. Annex C lists several hundred #12 ccc's in a 3 inch conduit. Again, not a box. However, if you are allowed so many current carrying conductors in conduits, why not boxes? I think this is the reason the inspector has limited the number of wires (specifically #12 thhn wires) per box, because if they were not running enough seperate conduits to the same box in order to keep the derating factor down (no more than 9 ccc's per pipe. because 30 amps X 70%=21 amps ......so a 20 amp breaker can still be used) then they would not be at an allowable ampacity sufficient to install a 20amp ocd on the wire, which article 240.4 D says we have to for a piece of copper 12 awg. Any thoughts? Am I wrong? Is there an article that limits the # of ccc's in a box of any size, no matter how large? They said the number was 30 to 40, they couldn't remember exactly. Heck, we can install 80 circut panels now that sq D makes. No more limit to 42 spaces. Any help here?