What is I thermal?

[speedtronic]

On electrical switching devices like contactors, a rating I thermal is mentioned. what does this mean?

 

[ghost]

Conventional Thermal Current.
Value of current the contactor can withstand with poles in closed position, in free air for an eight hour duty, without the temperature rise of its various parts exceeding the limits specified by the standards.

See, you learn something new everyday!

Here's where I found it!
ABB Low Voltage Contactors Technical Terms - Explanation Of Terms & Definitions

There's some good info there for the college boys.