ICC Residential Electrical Inspectors Practice Exam

What is the voltage rating typically used for residential branch circuits?

1. 120 volts

2. 240 volts

3. 480 volts

4. 600 volts

The correct answer is: 120 volts

Residential branch circuits are typically rated at 120 volts because this is the standard voltage for most household appliances and lighting circuits in North American residential settings. This voltage level is safe and suitable for a wide range of devices, including outlets for lamps, televisions, and small appliances. In homes, 120 volts is the most common voltage for general-purpose circuits, aligning with the design of many appliances which are manufactured to operate efficiently at this voltage. Higher voltages, such as 240 volts, are generally reserved for specific appliances that require more power, like dryers and ovens. The other higher voltage ratings, including 480 volts and 600 volts, are primarily used in industrial or commercial settings and are not suitable for residential wiring due to safety and compatibility issues with standard household devices. Therefore, the 120-volt rating is critical for ensuring that residential electrical systems can safely and effectively power typical home equipment.