Which option represents a common low-voltage value used in commercial/industrial contexts?

• A. 600 V
• B. 13,800 V
• C. 120/208/240/277/480 V
• D. 4,160 V

Answer: (C)

In commercial and industrial power systems, there are several standard low-voltage values you’ll encounter regularly. The most common lineup includes 120 V for general outlets, 208 V or 240 V for three-phase or single-phase loads in many buildings, 277 V used for lighting in larger facilities, and 480 V for three-phase motors and larger equipment. This mix reflects the practical voltages engineers design around for distribution, lighting, and motor circuits in typical facilities, making that option the best representation of common low-voltage values.

The other voltages listed aren’t representative of the usual low-voltage distribution you'll find in commercial/industrial settings: 13,800 V is a medium/high distribution voltage used for feeders, not low-voltage branch circuits; 4,160 V is also a higher distribution voltage used in industrial contexts; and while 600 V is a recognized equipment rating, it doesn’t capture the breadth of standard low-voltage voltages commonly used across buildings and facilities in the way the listed set does.