NCCCO Mobile Crane Operator 4 3 — Questions and Answers
Question 1: When operating a mobile crane near energized power lines, what is the minimum required clearance distance for lines rated up to 50 kV under OSHA standards?
- 3 feet
- 10 feet (Correct answer)
- 20 feet
- 50 feet
Correct answer: 10 feet
OSHA 1926.1408 requires a minimum 10-foot clearance from energized power lines rated up to 50 kV.
Question 2: A crane's load chart shows a capacity of 40 tons at a 30-foot radius. If the operator works at a 40-foot radius, what generally happens to the rated capacity?
- It increases
- It decreases (Correct answer)
- It stays the same
- It doubles
Correct answer: It decreases
As the load radius increases, the rated lifting capacity decreases due to increased moment (torque) on the crane structure.
Question 3: What is the primary purpose of an anti-two-block (ATB) device on a mobile crane?
- To limit swing speed
- To prevent the hook block from contacting the boom tip (Correct answer)
- To restrict travel speed during picks
- To monitor outrigger pressure
Correct answer: To prevent the hook block from contacting the boom tip
An ATB device automatically stops the hoist when the hook block approaches the boom tip sheaves, preventing two-blocking which can cause catastrophic failure.
Question 4: Which document must an operator consult to determine the correct reeving configuration for a specific lift?
- OSHA 1910 General Industry standard
- The crane manufacturer's load chart and operator manual (Correct answer)
- ASME B30.5 standard only
- The rigging company's internal procedures
Correct answer: The crane manufacturer's load chart and operator manual
The crane manufacturer's load chart and operator manual specify correct reeving based on the load weight and configuration.
Question 5: A mobile crane is set up on outriggers over a suspected underground utility. What should the operator do FIRST?
- Proceed with the lift using reduced capacity
- Call 811 to locate buried utilities before setup (Correct answer)
- Install cribbing and proceed normally
- Notify the rigger and continue
Correct answer: Call 811 to locate buried utilities before setup
Calling 811 (Dig Safe/Call Before You Dig) to locate utilities before setup is required to prevent striking buried lines during outrigger deployment.
Question 6: What does it mean when a crane's load chart is derated for 'pick and carry' operations?
- The crane may lift heavier loads while traveling
- The rated capacity is reduced because traveling with a load increases dynamic forces (Correct answer)
- Outriggers must be fully extended during travel
- The swing brake must be locked out
Correct answer: The rated capacity is reduced because traveling with a load increases dynamic forces
Pick and carry operations involve dynamic forces from travel that reduce safe capacity, so manufacturers derate the chart for these conditions.
Question 7: Under ASME B30.5, what is the minimum number of wire rope wraps that must remain on the drum when the hook is at its lowest working position?
- 1 wrap
- 2 wraps (Correct answer)
- 3 wraps
- 5 wraps
Correct answer: 2 wraps
ASME B30.5 requires at least 2 full wraps of wire rope to remain on the drum to maintain the rope's dead-end anchorage under load.
NCCCO Mobile Crane Operator 4 3
When operating a mobile crane near energized power lines, what is the minimum required clearance distance for lines rated up to 50 kV under OSHA standards?