# what Amp to use before entering service



## Dennis Alwon (May 9, 2009)

You would use 240v for the service because your loads will be split between the phases.


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## ftex (Mar 5, 2016)

Thank you.
to confirm my understanding, example:
if there is house with 150kva load 120/240.The cable entering house of "utility" transformer will be calculated as 150/240v =625 A 
So I pick my service cable based on 625A? as you confirmed, and not 150/120v=1250A.


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## ftex (Mar 5, 2016)

The reason i am confused, because many online calculators are requiring to enter voltage as L-N, which would be 120V. 
And Asking to enter full ampacity (A), and I thought the full ampacity will be always based on 120V.


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## backstay (Feb 3, 2011)

ftex said:


> The reason i am confused, because many online calculators are requiring to enter voltage as L-N, which would be 120V.
> And Asking to enter full ampacity (A), and I thought the full ampacity will be always based on 120V.



A load can sit across L to N or L1 to L2. But a service will split the load and only the unbalanced will go down the neutral.


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