Now I understand why Engineers go to school for 6 years, so they can learn how to make the electrician correct their work... I have a new 400A commercial service, engineer calculated out the load at 154A (the 400A is by request of owner) So, the smart one designed this: 400A (320 continuous) meter can, behind that within 3' are 2 - 200A MB panels fed from double lugs on the meter can (2/0 cu). The meter can is fed 125' of 2/0 copper underground to the power company handhole. The smart one says that he only has to feed to the connected load, (which would only be 1/0 anyway) And that the 2 - 200A mains have nothing to do with the wire sizing...
Ok, I say, the 2/0 service wire is protected by 400A disconnect (equivelent) and that he must size for 400A, which means he can spec parallel runs of 250 KCmil AL. The 2/0 Cu at the meter cans is sufficient to feed each panel.
Now, I asked my inspector, before I went nose to nose with the smart one, and my inspector says I can actually go with parallel 4/0 AL, something about next standard size and Art 240... I really want to build this right, tell the engineer why and be smart enough to defend my position. Mostly because the owner will eat the additional cost and he is trying to save money... The 400A is necessary because they will utilize it in the future with a Deli/resturant added (although plans do not specify this).
So, any words of wisdom? Thanks.
Ok, I say, the 2/0 service wire is protected by 400A disconnect (equivelent) and that he must size for 400A, which means he can spec parallel runs of 250 KCmil AL. The 2/0 Cu at the meter cans is sufficient to feed each panel.
Now, I asked my inspector, before I went nose to nose with the smart one, and my inspector says I can actually go with parallel 4/0 AL, something about next standard size and Art 240... I really want to build this right, tell the engineer why and be smart enough to defend my position. Mostly because the owner will eat the additional cost and he is trying to save money... The 400A is necessary because they will utilize it in the future with a Deli/resturant added (although plans do not specify this).
So, any words of wisdom? Thanks.