# 4/0 Al for 200amp service



## dogleg (Dec 22, 2008)

240.4b,240.6


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## frenchelectrican (Mar 15, 2007)

Sparky229 said:


> I met with the power company an the engineer said he is bringing 4/0 aluminum to my main . It will be 3phase 277/480 200 amp. In 2014 code book 75degree column 4/0 rated-180amps. Is this sufficient if I use the same?





dogleg said:


> 240.4b,240.6


Here the thing .,,

anything before POA ( point of attachment ) on POCO side they have different requirement for the service drop conductor sizeing ., ( they go by different codes )

Dogleg ., I am aware of that number but I am assuming the OP mention the POCO bringing the overhead drop so they are on it own gameset on conductor sizing .,,

to OP from the POA to the meter and from meter to the first OCPD you have to sized per NEC code side plus load caluation how big the conductor you can hit but becarefull some local codes may ask not to use common 4/0 al in commercial location they may will ask you to run 250 KCM al conductors which I do it often.


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## telsa (May 22, 2015)

The Poco Service Drop is in FREE AIR.

Your Riser will be a raceway. It collects heat all by itself, too.

You'd better figure on 250kCMIL x 4... that's 205A @ 75C.


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## frenchelectrican (Mar 15, 2007)

telsa said:


> The Poco Service Drop is in FREE AIR.
> 
> Your Riser will be a raceway. It collects heat all by itself, too.
> 
> You'd better figure on 250kCMIL x 4... that's 205A @ 75C.


That basied on Alum conductors ?


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## Going_Commando (Oct 1, 2011)

Sparky229 said:


> I met with the power company an the engineer said he is bringing 4/0 aluminum to my main . It will be 3phase 277/480 200 amp. In 2014 code book 75degree column 4/0 rated-180amps. Is this sufficient if I use the same?


If your load calc is less than 180A, then yes. If it is more than that, then no.


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## telsa (May 22, 2015)

Marc, XHHW aluminum, yes.

In COMMERCIAL practice, the expectation is that the load will eventually grow and grow.

It always does. So, today's load calc doesn't hold much meaning.

Hence, standards are more conservative.

Absolutely no-one wants to rip out 4/0 in a few years because they're undersized -- and roasting in the toasty riser every Summer.


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## frenchelectrican (Mar 15, 2007)

telsa said:


> Marc, XHHW aluminum, yes.
> 
> In COMMERCIAL practice, the expectation is that the load will eventually grow and grow.
> 
> ...


Thanks telsa for clear the details up that what I was looking for that part.

My sop typically run either 250 or 350 Kcm XHHW alum if the lugs have room for it . 

It is super rare for me to run 4/0 Alum conductors on 200 amp service unless it show less than 150 amp loads.,


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## backstay (Feb 3, 2011)

4/0 is residential only, commercial is always 250 and up for 200 amp. We also install at least 250 when feeding a heat only service(off peak). They are 160 amp continuous loads.


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## AK_sparky (Aug 13, 2013)

I just did my service with 250MCM. When I asked about 4/0, it would have actually cost more. The nuances of living on an island with a sparse population, where prices are highly driven by supply and demand. There is no demand here for 4/0 so it is special order!

I know that doesn't answer any questions, but I thought you'd find it interesting.


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