In regards to NEC 2014 250.122(B). Assume calculations show that a 370 wire sizing ampacity is required for a feeder, and #500 KCMI copper conductor is selected to feed this load from a 400 amp circuit breaker prior to upsizing for any reason with a #3 copper equipment grounding conductor (EGC). If, due to voltage drop, this feeder is changed to (2) parallel #250 KCMIL copper, to what size is the EGC to be increased to in this situation (as ratio of conductor sizes equals 1).
First we need to know if the revised installation is talking about conductors being installed in parallel, in multiple raceways.
"...this feeder is changed to (2) parallel #250 KCMIL copper"
How many raceways?