Electrical Hazards & Power Line Safety Flashcards
7 cards from real OSHA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Hazards & Power Line Safety flashcards as text
What must occur before anyone on the ground approaches or touches a crane that has made contact with an energized overhead power line?
Answer: The utility company must deenergize and confirm the line is safe
No ground personnel should approach until the power company has deenergized the line and confirmed it is safe, because ground current and step potential remain hazards until then.
What is 'step potential' in the context of crane electrical safety?
Answer: The voltage difference between two ground points that can drive current through a person's body from foot to foot
Step potential is the voltage gradient across the ground near an energized contact point that can cause lethal current to flow up one leg and down the other.
The minimum approach distances listed in OSHA's power line safety tables are determined primarily by which factor?
Answer: The voltage level of the power line
Minimum approach distances are voltage-dependent because higher voltage creates a larger arc-flash zone and requires more clearance to prevent electrical contact.
What does OSHA 1926.1408 require when power line voltage information cannot be obtained before crane operations?
Answer: Maintain at least 20 feet of clearance from the lines
When voltage cannot be determined, OSHA mandates a conservative default minimum clearance of 20 feet to account for the uncertainty.
Which practice best protects a crane operator from 'touch potential' hazards if the crane contacts an energized power line?
Answer: Remaining inside the cab without touching external metal surfaces
Staying inside the cab avoids bridging the crane's energized body to ground through the operator's body; touching external metal while also touching the ground or cab floor creates a lethal path.
Under OSHA 1926.1408, what assessment must be completed before lifting operations begin in any work zone containing overhead power lines?
Answer: A determination must be made whether any part of equipment or load could enter the minimum approach distance during operations
OSHA requires a pre-operation assessment to determine if the equipment, load, or rigging could encroach on the minimum approach distance at any point during the lift.
If an operator must evacuate a crane that is in contact with an energized power line, what technique minimizes the risk from step potential?
Answer: Jump clear of the crane with feet together, then shuffle or hop away in small steps
Jumping clear with feet together and shuffling or taking small hops minimizes the voltage difference between the two foot contact points, reducing step potential shock hazard.