Hi, I am in the process of installing a generator transfer switch. I have two sub panels that are seperated by a concrete slab (25 feet apart).
I have three unused 1 1/4 pvc conduits that are underneath the slab connecting both subpanels. (They are within ten feet of both panels).
I need to pull (2) 12 amp circuits and (2) 14 amp circuits through with thhn and properly box on both sides and continue with romex to isolate the circuits I need for the transfer switch. (I have 6 x 6 x 4 boxes to successfully pigtail the circuits).
I have read the NEC code book and would like to clarify the derating issue. I am staying with dedicated neutrals for each circuit and decided not to run any multi wired circuits. I just want to isolate the circuits for the transfer switch. So I have (8) current carrying conductors in 1 1/4 pipe (I want to keep them in one pipe so I have the other pipes for later use). The NEC states with 90 Degree I should only be worried about derating if the are more than 9 current carrying devices in the pipe.
I am correct with this interpretation or do I have to derate with 70 percent for conductors of 7-9. Do the nuetrals count as a current carrying conductor? Should I run 10 guage and 12 guage wire respectively in the conduit to help with derating? Or am I ok? any help is greatly appreciated.