What should a transformer output be rated for in a single-phase residential application?

In a single-phase residential application, the transformer output should typically be rated for either 120V or 240V, as these are the standard voltages used for residential electrical systems in many regions.

Most household appliances and lighting fixtures operate at 120V, making it the common voltage for most circuits. Additionally, 240V is used for heavy-duty appliances such as dryers, ranges, and some HVAC systems that require higher voltages for efficient operation.

Therefore, a transformer designed for residential use would need to accommodate these two voltage levels to support a wide variety of appliances and ensure that the electrical system meets the demands of common residential applications. The presence of both voltage outputs in the transformer allows homeowners to utilize equipment effectively without the need for additional transformers or converters.

The other options, such as 60V and 480V, do not align with standard residential voltage requirements, making them unsuitable for typical home use. 60V is below the threshold for standard household electrical systems, and 480V is too high for residential applications, as it is typically used in industrial settings for larger equipment and machinery where more power is necessary.