5' in what? ...raceway, wireway, enclosure, etc.??? If raceway, how long is it?Does this look correct or did I miss it::?
450 amp 3 pole breaker
if we run 3 conductors per phase 5'
we need to de rate by 30% per TABLE 310.15(B)(2)(a)
do we use 60c column of table 310.16
450+30% = 585 /3 =195 amp.
4/0 copper
May depend on the load too. Ampacity of the conductor(s) could be as low as 401A and still permitted to be protected by a 450A breaker. And there are even specific cases, such as motor circuits, which the ampacity of the conductor(s) could be even lower yet.Also your math is incorrect. You do not add your derating factor of 30% to the 450 amp load. The minimum ampacity would be 450 * (1/.7)= 643 amps
May depend on the load too. Ampacity of the conductor(s) could be as low as 401A and still permitted to be protected by a 450A breaker. And there are even specific cases, such as motor circuits, which the ampacity of the conductor(s) could be even lower yet.
Derate from 90?C column.daul rated THHN/THWN-2
I'm assuming this is a 3? 4-wire wye installation. As long as the neutral doesn't qualify as a current-carrying conductor, you wouldn't have to derate for number of conductors in each raceway. You will have to run a full-sized EGC in each raceway, though.Thank you
so if I run paralleled 4/0 THHN/THWN-2
in 2 conduits I wont have to derate
Thank you
so if I run paralleled 4/0 THHN/THWN-2
in 2 conduits I wont have to derate
3? 4-wire delta installation 120/240