NEC Commercial Electrical Practice Test

What voltage is usually computed for 2-wire small-appliance branch circuits in a dwelling?

1. 120 volts

2. 140 volts

3. 150 volts

4. 160 volts

The correct answer is: 120 volts

For 2-wire small-appliance branch circuits in a dwelling, the standard voltage is typically computed at 120 volts. This voltage level is commonly used in residential settings for powering a wide range of household appliances, lighting, and receptacles, making it a foundational aspect of residential electrical systems. The NEC (National Electrical Code) specifies that most general-purpose circuits in a home are rated at 120 volts, reflecting the typical single-phase electrical supply available in most residential areas. This ensures compatibility with the equipment and appliances commonly found in domestic environments. The other voltage options provided—140 volts, 150 volts, and 160 volts—are not standard for small-appliance branch circuits in residential settings. They might reflect special applications or specific equipment but do not apply to the typical electrical infrastructure for homes according to NEC guidelines. Hence, the focus on 120 volts underscores its practicality and widespread use in residential electrical design.