Can we use that section to calculate the demand?
It appears that this section on its face only applies to determining conductor ampacity.
Presumably by "demand" you are actually asking about a load calculation. Those are covered in article 220. It refers you to 630.11 and 630.31. However neither of those sections says much about load calculations only about ampacity of conductors.
So I don't know what that means.
That is similar to determining motor loads. 220.14(C) tells you that the load for a (single) motor should be calculated in accordance with 430.22. 430.22 doesn't really say anything about load calculations, only about ampacity of conductors.