When using a phase converter for a fixed load, what percentage of ampacity must the single-phase conductors have relative to the full load current rating?

When utilizing a phase converter for a fixed load, it is essential to ensure that the single-phase conductors can handle the electrical load effectively. For fixed loads, the National Electrical Code (NEC) specifies that the ampacity of the single-phase conductors should be capable of carrying a higher current than the full load current rating of the device being powered.

The correct answer highlights that the ampacity must be 250% of the full load current. This requirement is in place because phase converters can create a higher inrush current and draw additional current to accommodate the three-phase load on a single-phase system. It is important for maintaining the safety and efficiency of the electrical system, as undersized conductors may lead to overheating, reduced performance, and potential equipment failure.

Therefore, utilizing conductors with 250% ampacity ensures that they can handle any fluctuations or surges in current that may occur when operating the load through a phase converter, providing a reliable and safe operation.