Final answer:
Non-power limited circuits may operate with voltages up to 600 volts according to the National Electrical Code (NEC). Safety regulations require that these circuits conform to the standard design and installation practices to ensure safe operation at these voltage levels.
Step-by-step explanation:
According to the National Electrical Code (NEC), non-power limited circuits may operate with voltages as high as 600 volts. This is based on the standard safety protocols and electrical system design parameters that are used for the distribution of electrical power. Examples of such voltage levels are reflected in the way transformers reduce voltages from thousands of kilovolts at generation sites to levels appropriate for local distribution and end-user equipment. While electric power is usually generated at greater than 10 kV and transmitted at voltages over 200 kV to limit energy losses, the NEC mandates lower voltages, such as 120, 240, or 480 V at the user site to maintain safety. Non-power limited circuits should be designed and installed conforming to NEC safety regulations, which include setting the limit at 600 volts for continuous operation.