wire size 350 mcm for one large condo

[ponytl]

I hope you guys can at least put my mind at ease... I'm the contractor developer of a warehouse loft project...very hands on and being an old building alot has to be DOS (design on site) one unit of this project is aprox 10,000 sf (yes a 10,000sf condo/apartment) this unit is 3ph and has a 600amp service it's a 120ft run from the disconnect to the panel in the unit... on the material list it's calling for 350 mcm to feed this panel... I'm just wanting someone to put me at ease before i order $4000 worth of wire for this unit...
from reading this forum for awhile I know this is pretty mild compared to most i read... but thanks in advance for any opinions

pony

 

[iwire]

Re: wire size 350 mcm for one large condo

this unit is 3ph and has a 600amp service it's a 120ft run from the disconnect to the panel in the unit... on the material list it's calling for 350 mcm to feed this panel...

You have not given much info but I will take a run at this.

First as you say its 3 phase the 'easier' table Table 310.15(B)(6) can not be used.

You did not tell us the calculated load of this overachievers condo so I will have to assume that you need the full 600 amps of capacity.

OK, in general and based on limited info 350 aluminum is rated 250 amps and 350 copper is rated at 310 amps.

That said I can only guess that the plan calls for two sets of 350 copper per phase. for a total ampacity of 620 amps assuming the conductors are run in separate raceways or cables. If they are run in the same raceway the total ampacity would likely be 560 amps which may be fine assuming the calculated load is below 560.

You said its 120' of run.

That means you would be buying 960' of 350 copper.

Keep in mind I did a lot of assuming and guessing here. :shock:

 

[bdarnell]

If you are paying 4 grand for the wire, you'd BETTER be getting at least 960'.