When adjusting for temperature rating (150 degrees) the conductors are adjusted based on 90 degree ampacity (thhn) multiplied by the percentage on table 310.15 16 b2 then resized to 310.15 b16 conductor 90 degrees ampacity rating column. The wire then gets sized to the 75 degree column of the same table, correct?The ocpd get sized to the ampacity of 90 degrees and not 75degrees , right?
Calculation
- Thread starter Djelite
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Since the maximum terminal temperature is 75°C that will be your OCPD maximum ampacity.
Tulsa Electrician
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Djelite, Can you give an example. I think I'm following what your saying.
For example i had an apprentice ask me about sizing a conductor based on temperature. The temp was at 150 degrees. He was looking for 150 degree temperature wire. Although they do make 150 degree conductor I suggested to adjust conductor size base on 150 degrees. On table 310.15 b2 they give you a percentage to adjust by. Once you get that new rating you go to table 310.15b16 for wire size at 90 degrees for ampacity but sized to 75 degree at the same value for terminal terminations
Tulsa Electrician
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- Tulsa
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- Electrician
Got it. Thank you
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