It's important to understand that "non-conductor" and "insulator" mean the same thing. Both terms refer to materials that resist the flow of electricity.

Therefore, there is no material that is both a non-conductor and an insulator. They are synonymous.

Perhaps you're thinking of a material that acts as a conductor under certain conditions and an insulator under others? Here are some examples:

* Semiconductors: These materials like silicon and germanium can act as conductors under certain conditions, like when exposed to light or heat, and as insulators under other conditions, like at low temperatures.

* Gases: Most gases act as insulators under normal conditions. However, if the gas is ionized, it can become conductive.

* Water: Pure water is a good insulator. However, impurities like salts can make it conductive.

Let me know if you'd like to learn more about any of these examples!