So I have a question on how to figure vd on a continuous load. My understanding of the code is that I would do my voltage drop calc and compare that back to the size of wire needed for My continuous load and verify my wire is larger. If that is not explained very well, here is my math.
480v 3phase load - 30kva XFMR - so I end up with 36.1 amps
I am 3105' distance.
so when I start my voltage drop calc I used 37amps just to make sure I am covered. When all the math is finished I figured a 4/0 is needed to feed this XFMR. I just had an engineer tell me that I am missing the 125% on the wire size. Where is this coming from? Is this just something that this particular firm would do? Has anyone else run into this? I am a little frustrated since origionally the IE had a wire size of 500mcm - so being a dumb electrition I sent our an RFI and proposed a solution of 4/0. The wording of the reply did not sit well with me, but the IE did state that they would lower the size to 350's, but I can not get that math to work out. Any input would be great...
480v 3phase load - 30kva XFMR - so I end up with 36.1 amps
I am 3105' distance.
so when I start my voltage drop calc I used 37amps just to make sure I am covered. When all the math is finished I figured a 4/0 is needed to feed this XFMR. I just had an engineer tell me that I am missing the 125% on the wire size. Where is this coming from? Is this just something that this particular firm would do? Has anyone else run into this? I am a little frustrated since origionally the IE had a wire size of 500mcm - so being a dumb electrition I sent our an RFI and proposed a solution of 4/0. The wording of the reply did not sit well with me, but the IE did state that they would lower the size to 350's, but I can not get that math to work out. Any input would be great...