Engineer Please Explain

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I would say it’s only 10 feet, so why not just go with it.

But I think 300 Kim is sort of an odd size, and I don’t suppose it’s needed anywhere else on the job. And Im not sure that will fit on the transformer lugs, or the main lugs, and bending space might even be a problem.

And I agree I don’t see any reason for it to be upsized. It looks like the primary is sized for a 125 A breaker in LP.
 
Correct that #2 is SSBJ and not an EGC, my mistake there. And I believe #2 is still the correct size if the ungrounded conductors were 3/0.
 
kwired said:
Correct that #2 is SSBJ and not an EGC, my mistake there. And I believe #2 is still the correct size if the ungrounded conductors were 3/0.
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That looks right to me. And just depending on the exact type of wire and conduit, (4) 3/0 with the #2 gnd. might need a 2.5" conduit.

I'm starting to think typo also.
 
David Castor said:
My unpopular (on this forum) engineer's take: We don't know exactly why it was slightly oversized. As I used to tell contractors - the NEC is not a design guide. It's not outrageously oversized and I doubt it was a typo (maybe a copy/paste error). It's very common to size xfmr secondary feeders at 125% of the transformer rating. Perhaps there was some thought that the panel MB size might be increased at some point.
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Opinions are welcome that's why I posted this in the Engineer Forum. The panel main will likely not be increased in the future but you're point is well taken. The bus is 225 amps so the main OCPD could be increased by 25 amps in the future. The total load on the main is a little over 110 amps. Here's the panel schedule for section #1 which has the 200 amp main. Section #2 has about 50 amps worth of load.

UP-14N-1.jpg
 
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