[300.3(B)]. Use bigger raceway. You never "need"
to do this. In fact, it's prohibited. There is an exception in [300.3(B)(1)],
for a very special case.
[300.3(C)(1)]. Yes, but there's a catch: all of
the conductors must have an insulation rating at least that of the
maximum circuit voltage applied to any conductor in a given raceway,
enclosure, or cable. What this means generally is you should follow
the good engineering practice of putting runs of power,
signal, and control wiring in separate raceways and bundles wherever
possible. That way, you'll never violate this requirement.
[300.4]. You'll find the requirements for wood in
subsection A, for metal in subsection B.
[300.4(G)]. Protect the conductors with an
identified fitting that provides a smoothly rounded insulating
surface. You can skip this fitting, if you instead use insulating
material that is firmly fastened in place.
[300.4(H)]. A listed expansion fitting or other
approved means. This subsection is new, with the 2011 NEC.