Master Electrician Practice Exam

For lighting systems operating at 30-volts or less, what is the maximum rating for the output circuits of the power supply?

1. 15 amperes

2. 20 amperes

3. 25 amperes

4. 30 amperes

The correct answer is: 25 amperes

In lighting systems operating at 30 volts or less, the National Electrical Code (NEC) specifies that the maximum output current rating for the power supply circuits must not exceed 30 amperes. This limit is set to ensure safety in low-voltage systems, reducing the risk of any overcurrent conditions that could arise and ultimately minimizing the potential for electrical hazards such as overheating or fire. The focus on 30 amperes as the maximum output is significant because it aligns with the design of power supply systems to handle the loading effectively while also adhering to safety standards that protect both the equipment and users. Lower ratings, which may appear as options, would not be applicable in this context, as they do not meet the maximum capacity established for systems designed to operate at this specific voltage level. Hence, 25 amperes, 20 amperes, and 15 amperes, while safe, do not represent the maximum allowable current for these low-voltage circuits under the guidelines of the NEC.