NEC Commercial Electrical Practice Test

What is the maximum total voltage drop allowed on both feeders and branch circuits to the farthest outlet?

1. 3%

2. 5%

3. 7%

4. 10%

The correct answer is: 5%

The maximum total voltage drop allowed on both feeders and branch circuits to the farthest outlet is 5%. This standard is based on the National Electrical Code (NEC) guidelines which help to ensure that electrical systems maintain efficient performance and safety. Voltage drop is a reduction in voltage in the electrical circuit between the source and the load. Excessive voltage drop can result in inefficient operation of lighting and other electrical devices, potentially leading to overheating, reduced lifespan, and even failure of equipment. A voltage drop of up to 5% is generally accepted as a reasonable maximum for branch circuits and feeders. This level ensures that the equipment receives sufficient voltage for proper operation while minimizing the risk of performance issues. The first 3% of the allowable drop is often considered for branch circuits, while the remaining 2% can be used for the feeders. This combination helps maintain the overall integrity and functionality of the electrical system. Thus, understanding the permissible limits for voltage drop is crucial for ensuring the reliability and efficiency of electrical installations in commercial settings.