What is the voltage drop threshold for feeders alone that triggers an adjustment to feeder size?

What is the voltage drop threshold for feeders alone that triggers an adjustment to feeder size?

• A. 3%
• B. 1%
• C. 5%
• D. 7%

Answer: (A)

Voltage drop is the loss in voltage along a conductor under load, caused by the conductor’s resistance and reactance. When sizing feeders, designers aim to keep the voltage drop along the feeder to about 3% from the source to the farthest load. If the feeder’s calculated drop alone would exceed 3%, you resize the feeder (use a larger conductor) to bring that drop back to or below 3%. This keeps the overall system voltage drop within the commonly accepted 5% total limit (which includes service and other segments) and ensures equipment operates properly. The 5% total limit is for the whole path, not the feeder alone, and the other options aren’t the standard feeder-sizing threshold. So, the threshold is 3%.

Voltage drop is the loss in voltage along a conductor under load, caused by the conductor’s resistance and reactance. When sizing feeders, designers aim to keep the voltage drop along the feeder to about 3% from the source to the farthest load. If the feeder’s calculated drop alone would exceed 3%, you resize the feeder (use a larger conductor) to bring that drop back to or below 3%. This keeps the overall system voltage drop within the commonly accepted 5% total limit (which includes service and other segments) and ensures equipment operates properly. The 5% total limit is for the whole path, not the feeder alone, and the other options aren’t the standard feeder-sizing threshold. So, the threshold is 3%.