# 800 amp service



## HARRY304E (Sep 15, 2010)

sky6714 said:


> I am looking at a new 800amp meter stack for a multi unit commercial building.
> There currently is a ground mounted transformer for this with 2 - 4" pvc. conduits from the xfmr. to the 800amp switch.
> Instead of using 2 sets of 500mcm cu. I wanted to go with compact aluminum conductors, but was not 100% sure on size. 750's ?
> Thanks for your help !
> :001_unsure:


Look at Table 310.15(B)(16) 2011 NEC.



Welcome to the forum.:thumbup:


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## Dennis Alwon (May 9, 2009)

It depends if you have one run of conduit or two. If you have one you must derate. 750 al is good for 386 amps so two runs = 770. If the calculated is 770 or less then you can use 800 amp breaker per 240.4(B)


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## Cletis (Aug 20, 2010)

*3*

Pull 3 x 500's better


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## hardworkingstiff (Jan 22, 2007)

Cletis said:


> Pull 3 x 500's better


This doesn't make sense. 

2, 4" conduits and 3 sets of 500?


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## Cletis (Aug 20, 2010)

*Catch*

Good Catch! Someone is paying attention


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## McClary’s Electrical (Feb 21, 2009)

HARRY304E said:


> Look at Table 310.15(B)(16) 2011 NEC.
> 
> 
> 
> Welcome to the forum.:thumbup:


 
He can't use that table for parallel harry


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## Cletis (Aug 20, 2010)

*extra*

Don't you all have to run an extra empty one anyway?


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## McClary’s Electrical (Feb 21, 2009)

Cletis said:


> Don't you all have to run an extra empty one anyway?


 
Does anybody?


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## Cletis (Aug 20, 2010)

*oh*

Oh Yeah. Around here you "have to" run an extra conduit for future needs. they won't pass you if you don't


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## sbrn33 (Mar 15, 2007)

Cletis said:


> Oh Yeah. Around here you "have to" run an extra conduit for future needs. they won't pass you if you don't


Are you sure your not thinking of the primary side? It would be pretty rare if any AHJ "made you run an extra conduit" just because.

Or are you just fishing


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## Cletis (Aug 20, 2010)

*extra*

It must be a local thing then. We have to have it on the secondary side. Quite serious. they even make us run a stinkin 4" conduit for future fiber optic ??


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## Dennis Alwon (May 9, 2009)

mcclary's electrical said:


> He can't use that table for parallel harry


That is the same Table as 310.16 in the 2008 code. It is not (B)(6) but (B)(16). I think Harry gave the correct Table for 2011 as he stated.


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