What is the voltage specification for electrical services limited by the IRC?

The voltage specification for electrical services as limited by the International Residential Code (IRC) is 120/240 volts. This voltage range is commonly used in residential settings throughout the United States, as it provides a safe and effective means for powering typical household appliances and lighting systems.

The 120 volts is typically used for standard household circuits, while 240 volts is often utilized for higher-power appliances such as electric dryers, ranges, and HVAC equipment. This dual voltage supply allows homeowners to manage their electrical needs efficiently, as most standard outlets are designed for 120 volts.

In contrast, the other options represent voltage configurations that are not standard for residential services per the IRC. For example, 240/480 volts is more typical in commercial or industrial applications, where equipment requiring higher voltages operates. Similarly, 120/208 volts is commonly seen in commercial settings with three-phase systems but is not an IRC specification for residential service. Lastly, the 240/120 configuration also does not align with the IRC's specified service voltage for residential applications.

By adhering to the 120/240 voltage standard, the IRC helps ensure safety, compatibility, and efficiency within residential electrical systems.