What is the common voltage rating for residential service in the U.S.?

The common voltage rating for residential service in the U.S. is 120/240 volts. This configuration allows for both 120 volts and 240 volts to be available within the home, catering to a wide range of household appliances and electrical requirements. Most standard outlets in residential settings provide 120 volts, which powers typical appliances like lighting, TVs, and smaller kitchen gadgets. On the other hand, appliances that require more power, such as electric dryers, ovens, and HVAC systems, utilize the 240 volts supplied by dedicated circuits.

This standard is defined in the National Electrical Code (NEC), which provides guidelines for electrical installations and safety. The 120/240-volt system is widely adopted due to its efficiency in balancing the load across different circuits and its compatibility with many devices.

The other voltage ratings listed are not correct because they do not represent the typical residential service in the U.S. For example, 110/220 volts might seem similar, but it's an outdated specification and not as commonly used in contemporary installations. The 240/480 volts configuration is primarily used in industrial or commercial settings, while the 100/200 volts rating does not align with standard residential service.