Is it normal for the Self-regulating heating cable to stop working when it reaches a certain temperature?

Yes, it is normal.

Self-regulating heating cable works based on PTC (Positive Temperature Coefficient) polymer technology. Its internal resistance increases as temperature rises, which automatically reduces heat output.

When temperature reaches the thermal balance point, the heat generation nearly equals heat loss. The heating power falls to a very low level, creating the impression that the cable stops working.

When the temperature cools down, resistance decreases, and the cable will increase heat output again automatically.

This self-limiting characteristic protects the cable from overheating. However, if the cable loses heating function at a temperature much lower than its designed maintaining temperature, please check the power supply and installation conditions.