Dino9
Member
- Location
- Pomfret, maryland USA
For a 2400 amp 120/208 service what size Xfrmr would you deem correct?
Whatever size the power company provides.
On the other hand if this is under the NEC at least 870 kva.
were in the NEC does it specify anything about xfmr sizing?
Um... I'm not sure I understood all that, but the way to calculate this is:I have the answer buts its easy to screw up depending on how you calculate it. I=kvax1000 divided by 208x1.73. I made the mistake of multiplying 208x1.73=359.84. 1000kva =1,000,000 divided by 359.84=2779.012 but this is actually incorrect. You have to do the formula in order. 300kva is the correct answer because if you do the formula in order it comes out quite different. 300,000 divided by 208=1442.30x1.73=2495.19. By doing it in my head in 2 parts I managed to look like an idiot yesterday. Thanks to all who chimed in though. Remember kids, do your formulas in order.
Um... I'm not sure I understood all that, but the way to calculate this is:
(208V x 1.73 x 2400A) / 1000 = 864 kVA
Which is why Mr. iwire said your transformer should be at least 870 kVA. So you did it right yesterday. You only get 300 kVA if you divide by 1.73 instead of multiplying by it, which is not the way you calculate kVA.