# Conductor temperature of terminations



## Eddie702 (Aug 7, 2015)

Sizing a feeder for a residential service that carries the entire load from the meter main to the indoor panel. So the general rule is under 100 amps 60 deg C and over 100 amps 75deg. C. from the UL white book


It is common to size the conductors at 83% of the main breaker rating (residential) and take into account any derating for ambient temperature or # of conductors in the raceway.


So for 150 amp 150 x.83=125 amps. So I went with #1 copper 130amps at 75deg C. No derating for temp or # of wires needed. 


So far so good. So indoors connecting the existing branch circuits to the new panel the existing circuits are mostly 60 deg C wire.


I know this is nit picking but if you come in at 75C someone told me that everything in the panel had to be 75 c


Can't find anything in the code book that is clear on this. I have an older 1993 McGraw-Hill Handbook of Electrical construction Calculations
Thought the explanation was in there. Can't find it


Appreciate the help


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