NCCCO Power Line Hazard Identification and Safety Procedures 2 — Questions and Answers
Question 1: What is the minimum safe approach distance for a crane near power lines up to 350 kV?
- 5 feet
- 10 feet
- 20 feet (Correct answer)
- 50 feet
Correct answer: 20 feet
OSHA requires a minimum 20-foot clearance from power lines up to 350 kV for cranes and their loads. For higher voltages, greater distances are required.
Question 2: Before beginning crane work near power lines, what must the employer do?
- Nothing special if the power lines are higher than the boom
- Identify all power lines in the work area, determine voltages, establish safe approach distances, and create a work plan (Correct answer)
- Just tell the operator to be careful
- Contact the power company to turn off the lines
Correct answer: Identify all power lines in the work area, determine voltages, establish safe approach distances, and create a work plan
OSHA requires employers to identify power lines, determine voltages, establish and communicate minimum approach distances, and create a specific plan for safe operation near energized lines.
Question 3: What is an 'encroachment' or 'trigger' distance in relation to power lines?
- The distance where you get electrocuted
- A predetermined distance from the power line that triggers additional safety measures (dedicated spotter, slower operations) before reaching the minimum approach distance (Correct answer)
- The distance where the crane physically touches the wire
- The distance from the nearest power pole
Correct answer: A predetermined distance from the power line that triggers additional safety measures (dedicated spotter, slower operations) before reaching the minimum approach distance
The encroachment distance is a buffer zone beyond the minimum approach distance. When any part of the crane enters this zone, additional safety measures activate (dedicated spotter, reduced speed).
Question 4: If a crane contacts a power line and the operator cannot break free, what should they do?
- Jump out of the cab immediately
- Stay in the cab, warn everyone to stay away, and call for emergency help to de-energize the line (Correct answer)
- Try to back the crane away
- Turn off the crane's engine and exit normally
Correct answer: Stay in the cab, warn everyone to stay away, and call for emergency help to de-energize the line
The operator is safest inside the cab. If they exit while the crane is energized, stepping onto the ground while touching the crane creates a path for current through their body.
Question 5: What is 'step potential' and why is it dangerous near an energized crane?
- The potential to step on a crack in the ground
- Voltage difference between two points on the ground near an energized source — current flows through your body between your feet (Correct answer)
- The energy needed to step over a power line
- The potential for the crane to take a step
Correct answer: Voltage difference between two points on the ground near an energized source — current flows through your body between your feet
When current flows through the ground from an energized crane, voltage decreases with distance. The voltage difference between your two feet can drive current through your body — potentially lethal.
Question 6: Who is the 'dedicated spotter' when working near power lines?
- The crane operator's helper
- A person whose sole duty is to watch the clearance between the crane and power lines and alert the operator (Correct answer)
- The utility company representative
- Any worker who can see the power lines
Correct answer: A person whose sole duty is to watch the clearance between the crane and power lines and alert the operator
The dedicated spotter has one job: continuously observe the distance between all parts of the crane (boom, load, rigging) and the power lines, immediately alerting the operator if the distance decreases.
NCCCO Power Line Hazard Identification and Safety Procedures 2
What is the minimum safe approach distance for a crane near power lines up to 350 kV?