What's Hot and What's Not
How hot is too hot for electric motors and other components?
Sensing that something is "too hot to touch" may not mean that it is malfunctioning.
The temperature at which an item is "too hot to touch" falls in the range from 140-degrees Fahrenheit to 160-degrees Fahrenheit. This is equivalent to 60-degrees Celsius to 71-degrees Celsius.
Many mechanical and electrical components have normal operating temperatures at or above temperatures that are "too hot to touch".
Thus, using "too hot to touch" as a criterion for determining whether or not a component is malfunctioning, may not yield the correct answer.
You will need to use an infrared thermometer to accurately measure the temperature of a component and compare this reading to the normal operating temperature listed for the component.
An electric motor with Class H insulation is rated to operate at 180-degrees Celsius (356-degrees Fahrenheit).
This temperature rating is defined as being the maximum temperature at which the insulation can be operated to yield an average life of 20,000 hours.
This means that the motor can be operated at 180-degrees Celsius (356-degrees Fahrenheit) and the insulation will deliver an average life of 20,000 operating hours.
Electric motors are not operating continuously at their maximum rated temperature, however, you can see that the operating temperature could be well below the maximum rated operating temperature and still be considerably higher than the "too hot to touch" temperature.
"Too hot to touch" just cannot be used as a criteria for determining whether or not a motor is malfunctioning.
You must use a temperature measuring device and compare the operating temperature of the motor to the manufacturer's listed normal operating temperature for the application.