Don't know right off hand. But I do know that any breaker carrying at or near its rated current will heat up significantly. Most breakers are 40 C, meaning they will maintain their thermal trip characteristics til that point, I think...Loose connection at breaker?
"Burned in 30 seconds by 54°C, 5 sec. @ 60°C, 1 second @ 71°C."
No burn in 8 hrs. at 43°C.
Less than 40°C probably feels cool to the touch.
Anyone know the rise-above-ambient for a breaker carrying rated current? I doubt it is 24°C.
I have seen breakers in outdoor enclosures go way over their rated capacity because it was below freezing outside. There was a 20 A breaker with 32 A continuous, without tripping. I changed it for a new one, and almost the same thing. At any rate we had to reduce the load.