All of our explosion-proof motors(Class 1 Div.1 Group C & D) have an automatic-reset temp. switch that is wired in the control circuit. I was under the impression that the purpose is to open the control circuit in the event that the surface temp. exceeds the ignition temp. of the flammable vapors, and therefore designed into all similar E-P motors.
One of our Asian plants is specifying this temp. switch only for E-P motors over 15 HP.

Any thoughts?