# 120/208V and 120/240V service



## brian john (Mar 11, 2007)

Yes it is sometimes possible.

OR 
Set 3 smaller transformers.

Or depending on the loads you could go the buck boost route.

Set 3 or more boost XMFR's for 240 VAC loads.

and feed all 120 VAC loads from the 208/120 VAC panel.


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## wattsup20 (Oct 22, 2010)

What do you mean "set 3 smaller transformers"? 

Do you have any idea what the cheapest of those options would be?


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## HARRY304E (Sep 15, 2010)

wattsup20 said:


> To this point I've mainly dealt with branch circuits and I'm still pretty new to that, so I don't know much about service entry.
> 
> I'm working on a building that has both 120/208V and 120/240V load requirements and I'm not really sure how to address this issue.
> 
> ...



if you have 120/208 then you probebly have 480/277 volts avaliable so you can buy a tran that is 240/120 single phase:thumbsup: Welcome to the forum:thumbup:


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## brian john (Mar 11, 2007)

HARRY304E said:


> if you have 120/208 then you probebly have 480/277 volts avaliable so you can buy a tran that is 240/120 single phase:thumbsup: Welcome to the forum:thumbup:


Still would have the issue of unbalanced loads assuming he has 480/277 just because he has 2018/120 is like assuming he has a motorcycle because he owns a car.

Buck bost would be cheapest.

Your 900 amp load is 187 kva or a single 200 kva transformer, buy 3-75 kva transformers 208 to 120/240 VAC or buck boost with 3-30 kva buck boost, which would be hard to find so go with 6-15 kva buck boost. An inexpensive alternative.

Depending on the number of 240 VAC panels you need would determine the number of buck boost, this could simplify the job. I only say this as smaller buck boost are easier to find as they should be stock


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## jwjrw (Jan 14, 2010)

The nec allows more than one service on a building for different voltages or by special permission. We use buck boost transformers for this on a lot of jobs to boost the voltage to 240. It is usually the cheapest route for small loads. I agree with BrianJ


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## wattsup20 (Oct 22, 2010)

Awesome. Thanks a lot guys!


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