I am still waiting to see what happens when you have a panel stuffed with AFCIs and installed in an un-airconditioned garage.
I think we already know that answer... CLICK
CLICK
CLICK CLICK ... CLICK
...and that's it. The rest would cool down, see?
Thermal derating applies to the temperatures in the panel, not just in the garage. If that environment is going to exceed the rating of the panel, the panel shouldn't be there.
