# 350 aluminum feeding three 200 amp panels + 100 amp panel.



## dcarpe004730 (Nov 2, 2011)

So I have a commercial building that is fed with 350 aluminum underground for a 240v single phase system. Three 200 amp panels and one 100 panel is tied in inside the building. The owner would prefer not to have to dig for another service due to all the concrete that would have to be repaired. So the main question is; Can I avoid digging by using a step up transformer to 480v then use another transformer to step it down to 240v single phase? Is the existing 350 aluminum wire large enough for a plan like that?


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## backstay (Feb 3, 2011)

What is the total load? Is this already functioning or are you adding load? If you are adding, how much?


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## MotoGP1199 (Aug 11, 2014)

None of us can help you without actual load numbers. The panel sizes are almost useless at this point. It's like counting breaker handle amperage markings and saying you have exceeded 200 amps.


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## dcarpe004730 (Nov 2, 2011)

Not sure on load calculations yet. Regardless it will have atleast an 800 amp service.


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## dcarpe004730 (Nov 2, 2011)

I'll get back to you when I have those numbers.


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## backstay (Feb 3, 2011)

dcarpe004730 said:


> Not sure on load calculations yet. Regardless it will have atleast an 800 amp service.


800 amp service at 12/240? 350 mcm is going to be about 250 amp. Using 480 volts only doubles that to 500 amp once you step back down to 240.


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## dcarpe004730 (Nov 2, 2011)

backstay said:


> 800 amp service at 12/240? 350 mcm is going to be about 250 amp. Using 480 volts only doubles that to 500 amp once you step back down to 240.


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## dcarpe004730 (Nov 2, 2011)

Thanks


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## oldsparky52 (Feb 25, 2020)

You might be able to step it up to 600V instead of 480V and get more power to the building. The transformers I believe will be harder to get, and in this supply environment who knows how long it might take.


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## Almost Retired (Sep 14, 2021)

what if you dont transform at the poco pole at all
replace the feeder wires with HiV wire
and set a 240V/13800 padmount near the service entrance to the building


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## matt1124 (Aug 23, 2011)

Almost Retired said:


> what if you dont transform at the poco pole at all
> replace the feeder wires with HiV wire
> and set a 240V/13800 padmount near the service entrance to the building


This. Talk to a distribution engineer. If you’ve got the pipe in place already and it’s under concrete, this sounds like a great solution.


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## micromind (Aug 11, 2007)

If 350 isn't enough at 480 or 600 volts and you can re-pull 5KV wires, you can install a 120/240 - 2400 or 4160 volt transformer at each end. It's done on a regular basis at airports, the ones I've worked with are usually 10 to 25 KVA.

A 167 KVA single phase transformer will give 696 amps at 120/240 and 70 at 2400, 40 at 4160. The next standard size up is 250 KVA, this will deliver 1,042 amps at 120/240, 104 at 2400 or 60 at 4160.


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## micromind (Aug 11, 2007)

Almost Retired said:


> what if you dont transform at the poco pole at all
> replace the feeder wires with HiV wire
> and set a 240V/13800 padmount near the service entrance to the building


In this case, depending on the local PUCO, you might need to primary meter, this can get expensive. 

If they'd allow their transformer inside the building and they are willing to use the existing pipe for the primary, then it'd be the least expensive way to go.


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## dcarpe004730 (Nov 2, 2011)

S


micromind said:


> In this case, depending on the local PUCO, you might need to primary meter, this can get expensive.
> 
> If they'd allow their transformer inside the building and they are willing to use the existing pipe for the primary, then it'd be the least expensive way to go.


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## dcarpe004730 (Nov 2, 2011)

Good point this is in Lake Charles after hurricane Laura... they are bending the rules a little.


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## Almost Retired (Sep 14, 2021)

dcarpe004730 said:


> Good point this is in Lake Charles after hurricane Laura... they are bending the rules a little.


I am in Louisiana just south of I-20 on US167.... I also have *Entergy*
around here over 400amp is CT metered

If they secondary meter, you will need the meter outside of the building, regardless of where the CT can is placed
If they choose to primary meter, they will most likely do it all since you are not allowed to work on their equipment

Entergy has a website where they show all of the services they support and all of the requirements for each one.
it shows padmount requirements as well






Builder Services and Standards







www.entergy-louisiana.com





that website says to consult the company over 400amp
which means you will have to get an appointment with an engineer and do what ever they say.

running their primary inside your building probably wont fly because of the outside disconnect for fireman safety

I have gotten permission from the field engineer to call the district engineer about large services and what he will approve

_you definitely need to work with Entergy directly on this size service, do not bother starting any work until they approve a plan_


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## dcarpe004730 (Nov 2, 2011)

Almost Retired said:


> I am in Louisiana just south of I-20 on US167.... I also have *Entergy*
> around here over 400amp is CT metered
> 
> If they secondary meter, you will need the meter outside of the building, regardless of where the CT can is placed
> ...


Absolutely thanks


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## Southeast Power (Jan 18, 2009)

dcarpe004730 said:


> So I have a commercial building that is fed with 350 aluminum underground for a 240v single phase system. Three 200 amp panels and one 100 panel is tied in inside the building. The owner would prefer not to have to dig for another service due to all the concrete that would have to be repaired. So the main question is; Can I avoid digging by using a step up transformer to 480v then use another transformer to step it down to 240v single phase? Is the existing 350 aluminum wire large enough for a plan like that?


You can possibly avoid all of the hassles by performing a load calculation on the building to determine what the customer actually requires.
The building might have all of its lighting on several circuits or, it might have non-consequential loads, it could have dozens of receptacle circuits or abandoned circuits for removed equipment.


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## Almost Retired (Sep 14, 2021)

Southeast Power said:


> You can possibly avoid all of the hassles by performing a load calculation on the building to determine what the customer actually requires.
> The building might have all of its lighting on several circuits or, it might have non-consequential loads, it could have dozens of receptacle circuits or abandoned circuits for removed equipment.


I agree completely !!!!
Entergy will want some sort of reason to do what you are asking and a load calc will be what they want the most


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