A mobile crane with a 150-foot boom is being used to lift materials near power lines. The power lines are rated at 50kV. What is the minimum safe approach distance required?
Correct Answer
D) 10 feet
For power lines rated 50kV or below, OSHA requires a minimum approach distance of 10 feet for cranes and other equipment. Higher voltage lines require greater distances for safety.
Why This Is the Correct Answer
According to OSHA 1926.1408, for power lines rated 50kV or below, the minimum safe approach distance for cranes and derricks is 10 feet. This applies to any part of the crane, including the boom, load line, or load. The 50kV rating in this question falls within the 'up to 50kV' category, making 10 feet the correct minimum clearance distance required by federal safety regulations.
Why the Other Options Are Wrong
Option A: 6 feet
6 feet is insufficient clearance for 50kV power lines. This distance might apply to much lower voltage lines, but OSHA specifically requires 10 feet minimum for lines up to 50kV to prevent electrical arc flash and electrocution hazards.
Option B: 15 feet
15 feet exceeds the required minimum distance for 50kV lines. While maintaining greater clearance is always safer, OSHA specifically sets the minimum at 10 feet for voltages up to 50kV. This distance applies to higher voltage classifications.
Option C: 20 feet
20 feet is the required clearance for power lines over 50kV up to 200kV, not for 50kV lines. This represents confusion between voltage categories in OSHA's crane safety standards and would be unnecessarily restrictive for this voltage level.
Memory Technique
Remember '50 and 10': For power lines 50kV and below, keep 10 feet away. Higher voltages need more space, but 50kV or less = 10 feet minimum.
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