NCCCO Mobile Crane Operator 5 — Questions and Answers
Question 1: Under ASME B30.5, at what minimum distance from electrical power lines rated up to 50 kV must a crane boom maintain clearance?
- 5 feet
- 10 feet (Correct answer)
- 15 feet
- 20 feet
Correct answer: 10 feet
ASME B30.5 and OSHA 1926.1408 require a minimum 10-foot clearance for power lines rated up to 50 kV.
Question 2: When traveling a mobile crane with a load suspended, the operator must:
- Boom fully elevated and swing brake applied
- Follow the manufacturer's procedures and the lift director's direction, keeping the load as low as practical (Correct answer)
- Travel at normal road speed to minimize swing time
- Disengage the outriggers and retract the stabilizers completely
Correct answer: Follow the manufacturer's procedures and the lift director's direction, keeping the load as low as practical
Traveling with a suspended load requires manufacturer guidance, supervisor oversight, and the load kept low to reduce swing and instability.
Question 3: A wire rope's discard criteria include finding how many broken wires in one lay length for a running rope?
- 2 broken wires in one strand
- 6 broken wires in one lay length or 3 in one strand (Correct answer)
- 10 broken wires across the entire rope
- 1 broken wire in the core
Correct answer: 6 broken wires in one lay length or 3 in one strand
Per ASME B30.5, a running wire rope must be removed from service if 6 or more broken wires are found in one lay length, or 3 in a single strand.
Question 4: What is the primary purpose of an anti-two-block (ATB) device?
- Prevents the crane from exceeding its rated load
- Automatically stops the hoist and boom functions before two-blocking can occur (Correct answer)
- Measures the distance from the hook to the ground
- Limits the maximum boom angle during picks
Correct answer: Automatically stops the hoist and boom functions before two-blocking can occur
An ATB device detects when the hook block is dangerously close to the boom tip and automatically disables hoist-up and boom-down functions.
Question 5: Which factor does NOT directly affect a mobile crane's rated lifting capacity at a specific radius?
- Boom length
- Load line reeving (number of parts of line)
- The color of the load being lifted (Correct answer)
- Whether outriggers are fully extended or retracted
Correct answer: The color of the load being lifted
Rated capacity depends on radius, boom length, reeving, and outrigger configuration—the physical properties of the load, not its color.
Question 6: When is a crane operator permitted to leave the controls unattended with a suspended load?
- Any time the load is less than 50% of rated capacity
- Never, unless the load is safely landed and the crane is secured per manufacturer procedures (Correct answer)
- When the swing brake and hoist brake are both applied
- Only during a scheduled lunch break
Correct answer: Never, unless the load is safely landed and the crane is secured per manufacturer procedures
OSHA 1926.1417 prohibits leaving a suspended load unattended; the load must be safely landed before the operator leaves the controls.
Question 7: A radius increase during a pick (boom deflection or crane settlement) will:
- Have no effect on rated capacity if the load chart radius is correct
- Reduce the crane's rated capacity, potentially causing an overload (Correct answer)
- Increase the crane's stability margin
- Only affect capacity when the radius change exceeds 10%
Correct answer: Reduce the crane's rated capacity, potentially causing an overload
As radius increases, rated capacity decreases on the load chart, so any unintended radius growth moves the crane toward an overload condition.
NCCCO Mobile Crane Operator 5
Under ASME B30.5, at what minimum distance from electrical power lines rated up to 50 kV must a crane boom maintain clearance?