OSHA 10-Hour Construction ReviewFocus Four HazardsHard
A construction crew is working on a new building where overhead power lines are present. The lines are energized at 13.8 kV. What is the minimum safe clearance distance required between any part of the equipment (e.g., a crane boom) and these power lines?
- A10 feet
- B8 feet
- C15 feet
- D20 feet
Show answer & explanationAnswer & explanation
Correct answer: A. 10 feet
According to OSHA 1926.1408, for power lines energized from 50 kV to 350 kV, the minimum clearance is 10 feet. For lines less than 50 kV, the minimum clearance is also 10 feet, making 10 feet the general minimum for most construction scenarios involving lower voltage lines, and the starting point for higher voltages.
Why the other options are wrong
- B. 8 feet is too close for power lines, regardless of voltage, and does not meet OSHA minimums.
- C. 15 feet would be for lines between 350 kV and 750 kV, which is higher than the given voltage.
- D. 20 feet is required for even higher voltages (750 kV to 1000 kV) and is excessive for 13.8 kV, though safer.
Overhead Power Line Clearance (< 50kV)
Maintain a minimum 10-foot clearance from energized overhead power lines of 50 kV or less.
- Distance increases with voltage.
- Applies to all equipment, materials, and personnel.
- Contact with power lines causes electrocution, burns, and explosions.
Memory trick: Ten feet is keen when lines are unseen (or seen and mean).