75C Temp corrections factor

Eric Ernst

Various sources indicate that I can use 75C as a correction factor if my panels are 4" off the roof. Every source of correction factors I have found has had a correction for 70C (.56) and for 80C (.41). Is it permissible to split the difference to get the correction for 75C or do you need to go the the most conservative number (80C) when selecting wire size?

dwh

Re: 75C Temp corrections factor

Eric Ernst wrote: »

Various sources indicate that I can use 75C as a correction factor if my panels are 4" off the roof. Every source of correction factors I have found has had a correction for 70C (.56) and for 80C (.41). Is it permissible to split the difference to get the correction for 75C or do you need to go the the most conservative number (80C) when selecting wire size?

I believe that it's a range; 70C to 80C you use the number for that range - .56. 80 - 90 you move up to the next number - .41.