I have a main panel in my garage and I would like to install a subpanel in my basement. My plan is to run a 60A circuit to the subpanel (using 6/3 NM) as well as 2x 12/3 NM homeruns; one to feed 2 cirucits of lights and a second that would not be connected to my main panel yet, but would be available for convenience if I later wanted to add 2 more circuits in the basement. I was planning to use Schedule 40 PVC (inspector told me this would be fine), and the total run of conduit within the garage to the junction box in the basement will be approx 40' in length.
What size of PVC conduit would I need to satisfy conduit fill requirements? Would I be able to use smaller conduit sizes if I stripped the sheathing from the 14/3 and 12/3 cables?
In my research, I've come across this post (What type of wire for subpanel in attached garage?), and it seems that my cross-sectional areas would be:
6/3 650 mils 0.3316625 12/3 347 mils 0.094521 12/3 347 mils 0.094521
Resulting in a total area of
0.3316625 + 0.094521 + 0.094521 = 0.5207045.
In this post (How do I determine the fill rating of a conduit?), there's a table in NEC 2014 Chapter 9 Table 4 for PVC Schedule 40 indicating Over 2 wires requires 40% fill area; so it seems like 1 1/4" PVC would allow for .581" size, granting enough size for the .521" area that I believe I would have wih those 3 cables. Am I deriving this correctly?
Thanks for the help!