What rating ( kW ) is the heater ?
The thermal cut out has to be able to carry the full current of the heater without excessive self heating.
A fault in the heater could mean the current through the thermal cut out is higher than normal and self heating is causing the cut out to partial open its internal switch resulting in arcing and burn out of the device.
Most thermal cut outs are rated at 10 Amps maximum and thus can be used with heaters up to 2 kW.
Some devices are rated at less than 10 Amps and these would self heat when used with a heater that took more than the cut out's rated maximumm current.
The thermal cut out has to be able to carry the full current of the heater without excessive self heating.
A fault in the heater could mean the current through the thermal cut out is higher than normal and self heating is causing the cut out to partial open its internal switch resulting in arcing and burn out of the device.
Most thermal cut outs are rated at 10 Amps maximum and thus can be used with heaters up to 2 kW.
Some devices are rated at less than 10 Amps and these would self heat when used with a heater that took more than the cut out's rated maximumm current.