A rotary phase converter has a nameplate rating of 28 full load input amps. What is the minimum ampacity required for the conductor supplying the phase converter?

The minimum ampacity required for the conductor supplying a rotary phase converter should exceed the full load input rating of the device to ensure safe and efficient operation. In this case, with a rated input of 28 full load amps, applying the NEC (National Electrical Code) guidelines is essential.

According to the NEC, conductors should typically be rated for 125% of the continuous loads. Since a rotary phase converter can subject the conductors to continuous load conditions, this calculation is crucial.

When applying this guideline, the required ampacity can be computed as follows:

28 amps (full load input) × 1.25 = 35 amps.

This indicates that the conductor must be capable of handling at least 35 amps to accommodate the full load input safely. Therefore, selecting a conductor with a minimum rating of 35 amps aligns with electrical safety practices, ensuring that the wiring can manage potential overloads without risk of overheating or failure.

Choosing a conductor with ampacity below this calculated requirement could lead to various unsafe conditions, such as overheating and increased risk of fire hazards. Hence, the correct choice reflects the need for a conductor that meets or exceeds the 35 amps requirement.