Voltage drop and derating

[mountainscout]

We are installing #10 THHN for 20amp/277V lighting circuits because of the distance - (voltage drop)
We have 10 current caring conductors that we want to put in a single conduit, the derating of a #10 THHN is 20amps at 50% per table 310.15(B)(2)(a).
Is ther any other issues I'm missing because of the voltage drop and derating of the same condutors?
Thanks, Mark

 

[mistermudd]

Since voltage drop is only found in FINE PRINT NOTES and only a recommendation (unless you have local rules), the 10 #10 CCC should be protected at 20 amp max. I don't think you are missing anything else.