I agree with Bob and Charlie. I will just add that the whole voltage drop thing depends on your AHJ. As far as the NEC is concerned, the suggestion to limit the voltage drop to 5% is in a couple of "Fine Print Notes" or "Informational Notes", and is not part of the enforceable language of the Code. However, the City of Los Angeles, for example, enforces it as though it were part of the actual Code language. You can argue with the Building Department all you want, you can show them in the Code book where it says that it's just a suggestion (
not a requirement) you can file appeals, but at the end of the day you will lose.
They're strict about it, too -- less than 5% voltage drop from the service to the last outlet. Doesn't matter how large the building is. (Airport terminal with only one service? That last receptacle on the far side of the terminal had better not have a voltage drop over 5%!) "But can't we just make adjustments to the transformer taps to bring the voltage back up?" Nope. The rule says less than 5% voltage drop from the service to the last outlet. No exceptions.
On the other hand, none of the other jurisdictions I work in even ask for voltage drop calculations. I believe that's set to change next year, though -- last I checked, the new California Title 24 Energy Efficiency Standards make it an official requirement statewide.
SECTION 130.5 ?ELECTRICAL POWER DISTRIBUTION SYSTEMS
(c) Voltage Drop
1. Feeders. Feeder conductors shall be sized for a maximum voltage drop of 2 percent at design load.
2. Branch Circuits. Branch circuit conductors shall be sized for a maximum voltage drop of 3 percent at design load.
I checked your profile and wasn't able to find your location, so I apologize if the above is irrelevant for you.