In a residence, what is the standard voltage for a home service panel where a 150 A subpanel feeder originates?

In residential electrical systems, the standard voltage for a home service panel is typically 120/240 volts. This system provides both 120 volts and 240 volts, allowing for various types of electrical devices to be used effectively throughout the home. The 120 volts is commonly used for standard appliances, lighting, and outlets, while the 240 volts is utilized for larger appliances such as dryers, ovens, and HVAC equipment.

When a subpanel feeder originates from a main service panel rated for 150 amps, it usually draws from this 120/240-volt configuration. Therefore, a subpanel can supply both 120 and 240 volts to devices connected to it, ensuring versatility in the electrical system. This standard voltage helps ensure compatibility with the majority of residential appliances and fixtures, as well as compliance with electrical codes.

The other voltage options presented—such as 240/480 volts—are more typical of commercial or industrial settings and are not standard for residential use. Similarly, both 120-volt only and 240-volt only would limit the types of appliances that could be utilized in the home. Hence, the correct and practical voltage configuration for a residential service panel and its associated subpanels is indeed 120/240 volts.