In voltage drop calculations, which answer correctly identifies the typical allowable percentage of system voltage?

In voltage drop calculations, which answer correctly identifies the typical allowable percentage of system voltage?

• A. 1%
• B. 10%
• C. a few percent
• D. 50%

Answer: (C)

Voltage drop is the loss in voltage that happens as current flows through conductors due to their resistance and reactance. To keep equipment operating properly, this drop is limited to only a small portion of the supply voltage. In practice, that limit is a few percent, with common targets around 3% for feeders and up to about 5% total from source to load. So a few percent is the typical allowable range you’d use in voltage drop calculations. The other options are outside normal practice: 1% is usually too tight for practical runs, 10% would cause noticeable under-voltage for many devices, and 50% would be far beyond acceptable operation.

Voltage drop is the loss in voltage that happens as current flows through conductors due to their resistance and reactance. To keep equipment operating properly, this drop is limited to only a small portion of the supply voltage. In practice, that limit is a few percent, with common targets around 3% for feeders and up to about 5% total from source to load. So a few percent is the typical allowable range you’d use in voltage drop calculations. The other options are outside normal practice: 1% is usually too tight for practical runs, 10% would cause noticeable under-voltage for many devices, and 50% would be far beyond acceptable operation.