Certified Energy Auditor Practice Exam

Which lighting system is affected the least by a 10 percent reduction in voltage?

1. Incandescent

2. LED

3. Fluorescent

4. Compact fluorescent

The correct answer is: Fluorescent

The fluorescent lighting system is affected the least by a 10 percent reduction in voltage due to its operational characteristics. Fluorescent lights function by passing electricity through a gas, which then excites a phosphor coating on the inside of the bulb to produce light. They have built-in electronic ballasts that can help regulate the voltage and maintain a relatively stable light output even when there are fluctuations in voltage levels. When the voltage is reduced, fluorescent lights generally retain a good portion of their efficiency and brightness compared to incandescent lighting, which relies directly on the filament heating process. A decrease in voltage significantly impacts incandescent bulbs, as their light output drops sharply since they produce light through the thermal radiation of a heated filament. LED and compact fluorescent lights, while also being somewhat tolerant of voltage changes, can experience diminished performance or color shifts under a significant reduction in voltage when compared to standard fluorescent systems. The electronic components in LED systems can also create more sensitivity to voltage fluctuations than traditional fluorescent systems. Thus, fluorescent lights demonstrate a higher robustness against variations in voltage owing to their design and energy transfer mechanisms, making them the least affected by a 10 percent voltage reduction.