the motor is a 1/2 HP, not sure actual nameplate since its in the well case already. so 430-148 fla is 4.9, is that the number to plug into the Volt Drop formula for the "I"?

VD=2*K*I*L/CSA
VD=2*12.9*4.9*410/10,380
VD=51,832.2/10,380
VD=4.99

i thought "I" was always the breaker size it was connected to.?