Multifamily Dwelling Calculation

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wireguy8169

Senior Member
Location
Southern Maine
Ok, moved to Maine from PA, and am doing the 45 hour code course so I can either take my Journeyman's or Masters test, anyhow working on the chapters and for some reason I feel that my calculation is way off. I havent had to do it this indepth for many years and well I am not afraid to say I dont know something. Anyhow, the book used is Electrical systems 2008 NEC Callanan/ Wusinich ATP publications (if any of you have this book is why I am including this info)

I am doing the dwelling load calculations for Question 11 of the trade test and feel my calc for a six unit dwelling unit is way to high. I am not sure if I missed a deration or something but, I have gone over it following the NEC and examples in the text and still come up with my same KVA. I dont want someone to do it for me was hoping that someone may have this book or done it and could just tell me yes I am way off or am on the money if I am off I will figure it out. I came up with a total of 140427.5 VA phase and 58911.125 grounded its three phase and when I do the I= VA/208(1.732) . I should just trust my calculations but I know not doing it for a bit I may be missing something.

Thanks in Advance
 
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Npstewart

Senior Member
Why do you have 3 phase for mult family units? I could see for the house power maybe for the elevators..
 
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wireguy8169

Senior Member
Location
Southern Maine
I dont

I dont

This is a question in a book, the individual units are feed via a two pole breaker which doesnt really play into the question (at least not int he way the question is asked) the question is just asking for the demand based on the NEC for the line and nuetral to the building. The VA I posted are what I came up with was just hoping someone else had this book and may be or have done the questions in the 2008 45hr code course. The reason I am even taking it is to sit for the exam I have to have this for this state, did not have it for PA. Maybe thats where I am going wrong...

Thanks for your reply
 
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wireguy8169

Senior Member
Location
Southern Maine
Found my mistake

Found my mistake

Ok, found my mistake I was doing the equation 1404372.5/208*1.723 and I should have put the bottom part of the equation in (208*1.723) I came up with like 392 amps this is much more what I exspected for this install. Thanks for all input.

Thanks Again
 
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