What is the minimum distance to a power line of unknown voltage?

• A. 50 feet
• B. 10 feet
• C. 25 feet
• D. 100 feet

Answer: (A)

When working near power lines, you must treat an unknown voltage as potentially high and keep a generous clearance to prevent arcing or contact. Air can break down and electricity can arc across gaps, so the safe approach is a conservative distance that covers the possibility of higher voltages. The standard conservative distance for unknown voltage is 50 feet, which provides a practical safety buffer in most situations.

Distances like 10 feet or 25 feet don’t give enough margin if the line is actually high voltage, and 100 feet, while safe, isn’t necessary for typical practice and would hamper work unnecessarily. So, maintaining 50 feet away from a power line when the voltage is unknown is the correct, safest guideline.