According to NEC Article 328, how is medium-voltage cable defined?

Medium-voltage cable, as defined in NEC Article 328, refers specifically to solid dielectric insulated cable rated at 2000 volts or higher. This classification is important because medium-voltage cables are used in various applications requiring more robust insulation and construction to handle the higher electrical stress associated with their voltage ratings. By setting the threshold at 2000 volts, the NEC provides clear guidelines for installation, safety, and performance criteria, ensuring that the cables can operate effectively in their intended environments.

In contrast, the other definitions provided do not align with the NEC's classification for medium-voltage cable. For instance, cables rated at 1000 volts would fall into a different category, such as low voltage, and do not meet the specific criteria for medium-voltage designation. Similarly, a rating of 600 volts is too low, and while single-conductor cables rated at 1500 volts might be used in certain contexts, they also do not meet the threshold for what is considered medium-voltage cable.