A mobile crane with a 150-foot boom is being used near power lines. If the power lines are 50 kV, what is the minimum required clearance distance?
Correct Answer
B) 20 feet
For power lines rated 50 kV and over, OSHA requires a minimum clearance of 20 feet for cranes and other equipment. This distance increases with higher voltages.
Why This Is the Correct Answer
OSHA 29 CFR 1926.1408 specifically requires a minimum clearance of 20 feet for cranes operating near power lines rated 50 kV and over. This safety regulation is designed to prevent electrical contact and arc flash incidents that could be fatal to crane operators and nearby workers. The 50 kV threshold is a critical voltage level where the clearance distance significantly increases from lower voltage requirements.
Why the Other Options Are Wrong
Option A: 10 feet
10 feet is the minimum clearance required for power lines under 50 kV, not for 50 kV and above lines
Option C: 15 feet
25 feet exceeds the minimum requirement and while safer, is not the standard OSHA minimum for 50 kV lines
Option D: 25 feet
15 feet does not meet OSHA requirements for 50 kV lines and would create a dangerous safety violation
Memory Technique
50-20 Rule: 50 kV and over = 20 feet minimum clearance
Reference Hint
OSHA 29 CFR 1926 Subpart CC - Cranes and Derricks in Construction, specifically section 1926.1408
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