NCCCO MOBILE CRANE EXAM/100 QUESTIONS AND
ANSWERS (CRANE PRACTICE TESTS)
SECTION 1: SITE & GROUND CONDITIONS (Questions 1–12)
1. A crane is set up on outriggers over ground that appears stable. During the lift, one outrigger pad
sinks 2 inches. The load is still suspended. What is the FIRST action the operator must take?
A. Boom up to reduce the load radius
B. Swing the load toward the opposite side of the crane
C. Lower the load to the ground immediately
D. Retract the sinking outrigger to equalize pressure
Answer: C
Rationale: The immediate priority is to remove the suspended load from the crane. A sinking outrigger
indicates a loss of ground bearing capacity. Every second the load remains suspended increases the tipping
moment on the unstable side. Lowering the load stabilizes the situation. Never swing or boom up—these
motions change the center of gravity unpredictably and could accelerate tipping.
2. What is the MINIMUM distance that outriggers or tracks must be placed from the edge of an
excavation if the excavation is 12 feet deep?
A. 6 feet
B. 12 feet
, C. 15 feet
D. 24 feet
Answer: B
Rationale: OSHA requires that equipment be set back at least the depth of the excavation from the edge.
This is based on the angle of repose of soil (typically 45 degrees). A 12-foot-deep hole requires a 12-foot
setback. This prevents the trench wall from sliding out from under the outriggers. Even with this setback,
cribbing or mats may be required depending on soil type.
3. A crane is set up on a slope. The bubble level in the cab shows the crane is level within 0.5%. The
slope itself is 8 degrees. According to NCCCO standards, is this setup acceptable?
A. Yes, as long as the crane is level within 1%
B. No, the slope itself must not exceed 5 degrees
C. Yes, as long as outriggers are fully extended
D. No, the crane must be level within 0.25% on a slope
Answer: A
Rationale: The load chart validity requires the crane to be level within 1% regardless of the underlying
slope . The crane can be on a steep slope as long as the outriggers or tracks are cribbed to bring the chassis
to level. The critical factor is the chassis level, not the ground slope angle.
4. Which of the following soil conditions would provide the HIGHEST bearing capacity for crane
outriggers?
, A. Soft clay
B. Loose, dry sand
C. Compacted gravel
D. Saturated silt
Answer: C
Rationale: Compacted gravel provides the highest bearing capacity due to its interlocking particle structure
and drainage properties . Soft clay (low shear strength), loose sand (no cohesion), and saturated silt
(liquefaction potential) all have significantly lower bearing capacities. Always verify ground pressure
requirements against the load chart's "Ground Bearing Pressure" tables.
5. A controlling entity is required to ensure ground conditions are adequate. Who falls under this
definition according to OSHA 1926.1402?
A. The crane operator only
B. The rigging supervisor only
C. The employer who has the ability to prevent or correct ground conditions
D. The crane rental company
Answer: C
Rationale: OSHA defines the controlling entity as the organization that has the authority and
responsibility to address ground conditions . This is typically the general contractor or site owner. They must:
• Inform the operator of known underground hazards
• Ensure the ground can support the crane
• Coordinate with utility companies
, 6. A crane is set up with outrigger pads measuring 24 inches by 24 inches. The crane exerts a
maximum outrigger load of 80,000 lb. What is the ground bearing pressure in pounds per square
foot (psf)?
A. 10,000 psf
B. 15,000 psf
C. 20,000 psf
D. 40,000 psf
Answer: C
Calculation:
• Pad area = 24 in × 24 in = 576 sq in = 4 sq ft
• Pressure = Force ÷ Area = 80,000 lb ÷ 4 sq ft = 20,000 psf
Rationale: This is above typical soil capacities (most soils support 2,000–5,000 psf). This crane would
require cribbing or mats to spread the load over a larger area. A common rule of thumb: add cribbing until
pressure drops below 2,500 psf for most soils.
7. During setup, you notice that the ground under one outrigger appears to have been recently
backfilled. What should you do?
A. Proceed with setup but reduce capacity by 25%
B. Extend that outrigger further to reach solid ground
C. Require excavation to verify compaction or relocate the crane
D. Place extra cribbing under only that outrigger
Answer: C
Rationale: Backfilled ground is unreliable unless compaction testing has been performed. The operator
cannot assume it will support the crane. The only safe options are:
ANSWERS (CRANE PRACTICE TESTS)
SECTION 1: SITE & GROUND CONDITIONS (Questions 1–12)
1. A crane is set up on outriggers over ground that appears stable. During the lift, one outrigger pad
sinks 2 inches. The load is still suspended. What is the FIRST action the operator must take?
A. Boom up to reduce the load radius
B. Swing the load toward the opposite side of the crane
C. Lower the load to the ground immediately
D. Retract the sinking outrigger to equalize pressure
Answer: C
Rationale: The immediate priority is to remove the suspended load from the crane. A sinking outrigger
indicates a loss of ground bearing capacity. Every second the load remains suspended increases the tipping
moment on the unstable side. Lowering the load stabilizes the situation. Never swing or boom up—these
motions change the center of gravity unpredictably and could accelerate tipping.
2. What is the MINIMUM distance that outriggers or tracks must be placed from the edge of an
excavation if the excavation is 12 feet deep?
A. 6 feet
B. 12 feet
, C. 15 feet
D. 24 feet
Answer: B
Rationale: OSHA requires that equipment be set back at least the depth of the excavation from the edge.
This is based on the angle of repose of soil (typically 45 degrees). A 12-foot-deep hole requires a 12-foot
setback. This prevents the trench wall from sliding out from under the outriggers. Even with this setback,
cribbing or mats may be required depending on soil type.
3. A crane is set up on a slope. The bubble level in the cab shows the crane is level within 0.5%. The
slope itself is 8 degrees. According to NCCCO standards, is this setup acceptable?
A. Yes, as long as the crane is level within 1%
B. No, the slope itself must not exceed 5 degrees
C. Yes, as long as outriggers are fully extended
D. No, the crane must be level within 0.25% on a slope
Answer: A
Rationale: The load chart validity requires the crane to be level within 1% regardless of the underlying
slope . The crane can be on a steep slope as long as the outriggers or tracks are cribbed to bring the chassis
to level. The critical factor is the chassis level, not the ground slope angle.
4. Which of the following soil conditions would provide the HIGHEST bearing capacity for crane
outriggers?
, A. Soft clay
B. Loose, dry sand
C. Compacted gravel
D. Saturated silt
Answer: C
Rationale: Compacted gravel provides the highest bearing capacity due to its interlocking particle structure
and drainage properties . Soft clay (low shear strength), loose sand (no cohesion), and saturated silt
(liquefaction potential) all have significantly lower bearing capacities. Always verify ground pressure
requirements against the load chart's "Ground Bearing Pressure" tables.
5. A controlling entity is required to ensure ground conditions are adequate. Who falls under this
definition according to OSHA 1926.1402?
A. The crane operator only
B. The rigging supervisor only
C. The employer who has the ability to prevent or correct ground conditions
D. The crane rental company
Answer: C
Rationale: OSHA defines the controlling entity as the organization that has the authority and
responsibility to address ground conditions . This is typically the general contractor or site owner. They must:
• Inform the operator of known underground hazards
• Ensure the ground can support the crane
• Coordinate with utility companies
, 6. A crane is set up with outrigger pads measuring 24 inches by 24 inches. The crane exerts a
maximum outrigger load of 80,000 lb. What is the ground bearing pressure in pounds per square
foot (psf)?
A. 10,000 psf
B. 15,000 psf
C. 20,000 psf
D. 40,000 psf
Answer: C
Calculation:
• Pad area = 24 in × 24 in = 576 sq in = 4 sq ft
• Pressure = Force ÷ Area = 80,000 lb ÷ 4 sq ft = 20,000 psf
Rationale: This is above typical soil capacities (most soils support 2,000–5,000 psf). This crane would
require cribbing or mats to spread the load over a larger area. A common rule of thumb: add cribbing until
pressure drops below 2,500 psf for most soils.
7. During setup, you notice that the ground under one outrigger appears to have been recently
backfilled. What should you do?
A. Proceed with setup but reduce capacity by 25%
B. Extend that outrigger further to reach solid ground
C. Require excavation to verify compaction or relocate the crane
D. Place extra cribbing under only that outrigger
Answer: C
Rationale: Backfilled ground is unreliable unless compaction testing has been performed. The operator
cannot assume it will support the crane. The only safe options are:
