New York State Master Electrician Practice Exam 2026 - Free Electrician Practice Questions and Study Guide

The correct voltage system for a multi-family building with 12 units is 120/240V. This voltage system is commonly used in residential settings and is particularly suited for multi-family dwellings.

In such buildings, the 120/240V system provides an adequate supply for typical household appliances and lighting, allowing for both standard 120V outlets and special 240V appliances. This configuration is especially favorable for residential installations due to its balance between efficiency, safety, and the availability of compatible appliances and fixtures.

The other voltage systems listed are generally more suited for commercial or industrial applications. For example, 120/208V is often utilized in commercial buildings or in situations where three-phase power is necessary. The 240/480V system, on the other hand, is typically reserved for heavy machinery and industrial settings due to its higher voltage capacity and is not ideal for typical residential applications. Lastly, the 277/480V system is commonly used in commercial lighting applications and industrial settings, not for residential buildings.

Thus, 120/240V is the preferred choice for providing the necessary voltage for a multi-family residential building with 12 units, ensuring safety and meeting the electrical requirements of residential living spaces.