On Thu, 25 Jun 2009 23:24:14 -0500, Ignoramus21117
wrote:



What surprised me was that this 7.5 HP motor has insulation class F
and, apparently, it would be normal to see a rise in temperature to
311 degrees F during continuous operation,


The label only indicates that it has class F insulation. It doesn't indicate
the design temperature rise. Class F insulation with class B temperature rise
has been fairly standard for more than 30 years.

A motor that didn't have at least class F rated insulation would not be worth
manufacturing these days.


Mark Rand
RTFM