Size wire for 350 amp service

[bth0mas20]

When installing service above ground for a 350 amp (one 200 amp and one 150 amp main breaker panels) what size wire is allowed. This is a commercial location...not a dwelling. I will be
using copper conductors.

The reason I ask is because the standard around here with inspectors for 400 amp is to use 500
kcmil which is rated for 380 amps at 75 deg c. So if thats the case is 350 kcmil good for 350
amp as a service.

The inspectors Are you back home so I can stop by and look at the ac breaker? care about load
calcs on the service. They make that very clear. They only care that their is 350 amps between the two main breakers.

 

[tortuga]

If they are existing commercial meters I usually call the power co and get the peak demand then do a load calc based on that.
Goes like Peak demand for the lasst 18 mo's * 125% + new loads. Otherwise 400kcmil

EDIT: see 2011 NEC 220.87

 

[bth0mas20]

disregaurd the "Are you back home so I can stop by and look at the ac breaker?" That was not supposed to be in the post. Multi tasking and not proof reading got me.

 

[ceb58]

What is the load calculation on the building? Just because you have a 200 amp panel and a 150 amp doesn't mean you need a 350 amp service.

 

[texie]

disregaurd the "Are you back home so I can stop by and look at the ac breaker?" That was not supposed to be in the post. Multi tasking and not proof reading got me.

No harm, no foul. Kind of like email......there should be a 5 minute "changed my mind rule"

But as ceb58 said, just because you have a 150 and a 200 disco, that in and of itself does not require a 350 amp service.