[RE-wrenches] Temperature Compensation calcs for wire
William Miller
william at millersolar.com
Wed Jan 22 16:32:20 PST 2014
Friends:
I try to be rigorous in application of NEC codes to everything I do,
including wire sizing. I understand that even though I am using conductors
rated at 90°C, the breakers I use have terminals rated at 75°C so when
deriving the values for ampacity for a given gauge from the tables, I have
to use the 75°C column.
What is not clear, however, is which column I use when applying temperature
derating. Table 315(B)(2)(b) has a column for 75 and a column for 90. I am
using 90° wire. The values for 90° are much more generous than the 75°
values and I would like to use them. Which is correct?
As always, thanks to everyone on this list for all of the help and advice.
William
Gradient Cap
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600
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