You are planning to use a mobile crane with a 150-foot boom to lift materials to the 12th floor of a building under construction. What is the minimum distance the crane must maintain from overhead power lines carrying 50kV?
Correct Answer
C) 20 feet
For power lines carrying 50kV, OSHA requires a minimum clearance of 20 feet for crane operations to prevent electrical contact and electrocution hazards.
Why This Is the Correct Answer
OSHA 1926.1408 establishes specific minimum clearance distances for crane operations near overhead power lines based on voltage levels. For power lines carrying 50kV, the regulation mandates a minimum clearance of 20 feet to prevent electrical arcing and electrocution hazards. This clearance distance accounts for the electrical field around high-voltage lines and provides a safety buffer for crane boom movement and potential electrical discharge.
Why the Other Options Are Wrong
Option A: 10 feet
10 feet is insufficient clearance for 50kV power lines and would create a serious electrocution hazard, as this distance is only appropriate for much lower voltage lines.
Option B: 15 feet
15 feet does not meet OSHA requirements for 50kV lines and would still pose significant electrical safety risks to crane operators and workers.
Option D: 35 feet
35 feet exceeds the minimum OSHA requirement for 50kV lines, though it would be safer, it's not the minimum distance required by regulation.
Memory Technique
Use '50kV = 20 feet' as a key reference point, with lower voltages requiring less clearance and higher voltages requiring more clearance in the OSHA table.
Reference Hint
OSHA 1926 Subpart CC - Cranes and Derricks in Construction, specifically 1926.1408 Power line safety
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