99NEC Ch.9 Notes to Tables “A multiconductor cable of two or more conductors shall be treated as a single conductor for calculating percentage conduit fill area. For cables that have elliptical cross sections, the cross-sectional area calculation shall be based on using the major diameter of the ellipse as a circle diameter.”
Not sure if this would be the case for “Over 2 Wires: 40%” or “1 Wire: 53%” fill.
10/3 NM-B will probably need larger than ½-inch tubing.
