Hey Derek,
we are still talking of the calculation of the (missing in manual and nameplate) maximum input current rating of this VFD and what to tell someone who wants to connect it, what circuit one would need. You have the specs of the three-phase output current it can deliver: 20 A 110 ±20% V 3~.
Anyone can verify by calculation, and especially if you are an electrician, you should be able to simply calculate what total currents are flowing in a three phase current of known current and voltage at any time. And if you have a device that draws this power from one single phase input, nobody can have a doubt on what I explained above. You don’t want to tell that if you know for sure a device is able to draw at least 40 A as maximum input current (and that it’s what should be in the manual and the nameplate), that it is correct to recommend to the people to connect it to a circuit that is too weak for this, just because the input rating is (willingly) not there? Sorry for the question, I only ask to be sure.
I always say, to connect a VFD, you need an electrician – I want to be sure that it is still a correct recommendation 
What do you mean by this? Please could you explain what you mean.