Conductor Amapacity of Direct Buried Feeders

[LadyUser]

I am working on the design of a PV power plant. The array layout requires that I route 4 sets (positive, negative) conductors adjacent to one another in a trench. This adjacent run is less than 10% of the entire length of the feeders. Is there a section in the NEC that will allow me to base my amapacity calculations on the 90% (2 set) portion of the run versus the 10% (4 set) portion of the run? I was told that this was acceptable...but I can't find it in the Code Book. help please!!

 

[charlie b]

I don't know if this will answer your question, but I think the words you are remembering are from 310.15(A)(2), Exception (2008 NEC).

 

[LadyUser]

Thanks Charles! This is exactly what I was looking for!