Help me size feeders for 30 kva Transformer

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Mattula

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Hi everyone. I haven't done this since apprentice school and I am second guessing myself. I need to size the primary and secondary feeders for a 480D to 120 y 208 volt dry type transformer. The secondary conductors are to serve a lighting and appliance panel of undetermined load.

I used to have a handy card chart from square d but of course.......I cant find it. I looked on they're site and it said........

Full Load Currents (In Amperes) For Three-Phase Transformers
Voltage (Line-to-Line)

30KVA Transformer= 83A secondary (208v) and 36A Primary (480v)

I thought I recalled the secondary at 120V being approx. 100 Amp??
Your advise would help set me back on the right track.
 
Your numbers are on track.
Secondary would be 83 amps, I believe, x 1.25 = 104 or 100 amp OCP.
 
(a) 30000/208/1.732=83 x 1.25 = 104
using 100 OCP #3 THHN 75? 100 amp.

(b) because of 110.14, #1 ampacity would normally eb omited to 130 amps.
 
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