What minimum clearance should be kept from a power line of unknown voltage?

• A. 50 feet
• B. 15 feet
• C. 75 feet
• D. 100 feet

Answer: (A)

Keep a generous buffer around overhead power lines when the voltage isn’t known. If you don’t know the voltage, you must assume a higher-risk scenario and use the larger safety margin of fifty feet. Electrical arcing can jump gaps that aren’t obvious, and as equipment moves or the line shifts, staying at least fifty feet helps prevent contact or flashover even if the exact voltage is unknown. If the voltage were known, there are specific, smaller clearances for certain ranges, but with unknown voltage you can’t rely on those, so fifty feet is the prudent default.