[RE-wrenches] Sizing 3 phase OCPD - main

[Rebekah Hren]

Hi wrenches, 

I have a
question about sizing the main OCP breaker for a panel combining the output of
several true three-phase output inverters. To be precise - 10 of the  Refusol 20kW, which connect to  480V/277 Y with a max output of 24.1 amps, each
inverter has a 3 pole breaker, line a, b, c and a neutral, which doesn’t
apparently carry any current. 
 
Recommended
interconnection breaker is 35 Amps. Ok fine, but what should the main breaker and
main panel busbar rating be? 
 
What I’m not
sure about is if this is the right equation for the main breaker in a panel combining all ten inverter outputs: 
10  x 24.1A x √3
x 1.25  = 521.8 A
 
or is this the
right equation:
10 x 24.1A x
1.25 = 301.25 A
 
The busbar
rating should be easy, once I get the main disco OCPD figured out. 
Main OCPD + (10
x 35)  ≤ 120% busbar rating


Thanks for the help!
Rebekah Hren
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