You really need to go over article 430, it is not that simple.
Here in no particular order are all things that need sizing, #2 is required to be sized from the nameplate rating.
1)Motor Circuit Conductors
2)Motor and Branch-Circuit Overload Protection
3)Motor Branch-Circuit Short-Circuit and Ground-Fault Protection
The circuit breaker will not really have a relationship with the wire size, you may have 14 AWG on a 40 amp breaker.
Article 430 is one the articles listed in 240.4(G) so 240.4(D) does not apply to 10, 12, and 14 AWG.
Construction & Maintenance Electrician