Medium Voltage Conductor Sizing in underground duct

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Alangi1361 said:
May I ask what type of software does the analysis for duct banks?
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Several of the more expensive and more capable programs have the ability to do ductbank ampacity calculations. But my favorite is AmpCalc by Calcware. http://www.calcware.com/ It is easy to use, and relatively inexpensive (at least compared to programs that also do load flow and short circuit calculations). This one only does ampacity calculations for ductbanks and aerial runs. Keep in mind that even if the software has a well-established reputation for accuracy, the calculation would still need to be performed under engineering supervision.

 
Thank you all for your help.
I talked to my supervisor, and he said, the numbers in NEC are super conservative.
We will have that case,395 ampacity, if we are drawing full load on all feeders at the same time which is a rare case.
However, the design is under the review at the plan checker and we will see his comments very soon.
 
Alangi1361 said:
Thank you all for your help.
I talked to my supervisor, and he said, the numbers in NEC are super conservative.
We will have that case,395 ampacity, if we are drawing full load on all feeders at the same time which is a rare case.
However, the design is under the review at the plan checker and we will see his comments very soon.
Click to expand...
Just set the breaker trip to match the wiring ampacity and avoid the whole hassle.
 
Alangi1361 said:
.
I talked to my supervisor, and he said, the numbers in NEC are super conservative.
We will have that case,395 ampacity, if we are drawing full load on all feeders at the same time which is a rare case.
However, the design is under the review at the plan checker and we will see his comments very soon.
Click to expand...

The NEC is conservative. But you still can not put a 600 amp breaker on a 400 amp conductor.
 
Yes, that is plan B, if we want to keep the one-set feeders, changing the setting of the CB.
However, it is not something we like to do, because then we will be limiting our capacity probably for something unlikely to happen.

Looks like the medium voltage design is very new to our plan checker as I have not still heard back from him.
 
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