Tex:
IF cooling airflow was required, then mfg's would install ventilation fans on the panels.
Heat disapation from branch circuit breakers is dependent of heat from adjacent cb's. Multiple cb's that operate 'warm/hot' and are next to each other cannot disapate heat. Add to this that heat 'rises'. I don't know the engineering terms, but I see the above in real life.
One situation was 1/2 size GE breakers installed in a comm application, lighting circuits loaded to 12 amps, (#10 awg) and the branch breakers were HOT. Replaced cb's, same situation....removed circuits to a sub-panel, installed full size cb's, problem gone.
John
