Maximum safe temperature for class H insulation material is

There is 7 class of insulating materials, each suitable for different application:

The permissible temperature limit at which the insulators may be worked safely without deterioration depends upon the type and class of the insulation as detailed below.

Class Y - Maximum temperature 90°C

Class A - Maximum temperature 105°C

Class E - Maximum temperature 120°C

Class B - Maximum temperature 130°C

Class F - Maximum temperature 155°C

Class H - Maximum temperature 180°C

Class C - Maximum temperature above 180°C (limited stability up to 225°C)