VD in huge greenhouse 277v

[tortuga]

I have a commercial job that the grow lights are at the longest 300’ away from my contactors which are 100’ feet away from the branch bolt on breakers, which are 200’ away from SES which is 100’ from transformer. I have ran #8 to the contactors from 30 amp breakers (100’) (3” pvc UG), and #10 from contractor to the 1000 watt light (300’ max) (3/4” EMT), each circuit got its own neutral, 277/480Y, 6 lights per circuit @ 6,000w / 277 = 22 amps.
I’m not too worried but my questions are:
- is voltage drop usually calculated from transformer, or SES for 5%?
- is there such a buck boost that could do 277v to say 300 v?
- I can't fit #8 in 3/4” emt so what would you guys do? 4 lights per circuit
- do you find these new ballasts operate at a wide range voltage even when it simply says 277v?

Strombea: I just realized you have several errors in your branch circuit load calcs.
You have made the classic mistake of adding up HPS lamp watts see:

(B) Inductive and LED Lighting Loads. For circuits supplying
lighting units that have ballasts, transformers, autotransformers, or
LED drivers, the calculated load shall be based on the total ampere
ratings of such units and not on the total watts of the lamps.

Use the namplate amps of the ballasts as the basis for your calculation.
Then per 210.19(A) you add 25% to that, as those HID lamps typically run for 3 hours or more.
Voltage drop aside, I doubt you will be able to have 6 HID lights on a circuit and be NEC compliant.