For listing requirements, appliances supplied at least which voltage must be listed?

• A. 60
• B. 50
• C. 100
• D. 120

Answer: (B)

The main idea is safety listings: products connected to a power source must be evaluated and labeled when they operate at or above a certain voltage. That threshold is 50 volts. So any appliance designed to deliver 50 volts or more to a user or to other equipment must be listed by a recognized testing laboratory. This ensures proper insulation, protective features, and reliable construction for typical use. The specific voltages shown in the options (60, 100, 120) are common operating voltages, but they aren’t the threshold itself—the minimum that requires listing is 50 volts.