me and my partner have a question regarding VD. our field engineer wants to run #6 thhn for a 40amp 208v circuit @ 320'. we did the calculation and it was way over the allowable %. our engineer says that he did the calculation at 20amps, because that will be the max that is used. this is for a UPS and the breaker feeding this circuit will be a 40amp double pole. will this drop affect the UPS? and do you not have to then use a twenty amp breaker?