My question has to do with ampacity of feeder conductors in parallel.
Parallel feeds must follow 310.10(H), last time I checked.
310.10(H) states that it's only allowed if one follows 310.10(H)(2) through 310.10(H)(6)
310.10(H)(4) requires an ampacity adjustment per 310.15(B)(3)(a)
ASSUME NEUTRAL IS A CONDUCTOR
310.15(B)(3)(a) states that for four (4) conductors, the ampacity is reduced to 80%
I have someone trying to install an 800-amp parallel feed (800-amp CB) using 2 sets of 500MCM.
To me, 500MCM is good for 380-amps (assume 75-degree C rated terminations on equipment)
760 x 80% = 608 amps
Next size larger breaker permitted per 240.4(B) = 700-amps
If the load calculation is greater than 608-amps, they will need larger wire.
If the load is less than 608-amps, they can stay with the 500MCM provided that they use a 700-amp breaker.
Would you agree? Am I right? I think I'm right.