100+ Free NCCCO Digger Derrick Practice Questions

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Sling angle affects rigging load because:

Slings at 30 degrees from horizontal carry far less tension than at 60 degrees

Sling angle does not affect tension

Slings at smaller angles from horizontal carry significantly higher tension than at larger angles

Sling tension equals load weight regardless of geometry

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2026 Statistics

Key Facts: NCCCO Digger Derrick Exam

Written Exam Questions

NCCCO DDO Candidate Handbook

90 min

Written Time Limit

NCCCO DDO Candidate Handbook

70%

Specialty Passing Score

NCCCO scoring policy

10 ft

Table A MAD up to 50 kV

29 CFR 1926.1408

5 yrs

Certification Validity

NCCCO program rules

1926.1400(c)(4)

Utility-Work Exemption

29 CFR 1926 subpart CC

As of May 13, 2026, the NCCCO Digger Derrick Operator (DDO) program still uses a 75-question written exam (90 minutes) plus a practical skills test, with NCCCO standard passing thresholds. Most digger derrick work for utility and telecom line construction is exempt from OSHA's cranes-in-construction operator certification under 29 CFR 1926.1400(c)(4) so long as the work complies with 29 CFR 1910.268 or 1926 subpart V; outside that scope, the operator must be certified under 1926.1427, and NCCCO DDO is the standard route.

Sample NCCCO Digger Derrick Practice Questions

Try these sample questions to test your NCCCO Digger Derrick exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Before extending the outriggers on a digger derrick, the operator must first verify that:

A.The truck transmission is in gear

B.The ground supports the rated load without unacceptable settlement

C.The boom is fully retracted toward the rear

D.Tire pressure is at maximum rated value

Explanation: Outrigger pads transfer the entire weight of the truck plus the load and a dynamic factor onto a small footprint. The operator must verify the ground or supporting surface can carry that load without dangerous settling, soft-soil collapse, or buried-void failure, and add cribbing as needed.

2An outrigger pad sinks unevenly during setup on freshly graded fill. The correct response is to:

A.Continue setup because the outrigger jack will compensate

B.Stop, retract the outrigger, and add engineered cribbing or move to firm ground

C.Lower the boom so weight shifts to the other side

D.Drive the truck back and forth to compact the soil

Explanation: Uneven settlement is the warning sign of unstable supporting material. The operator must stop, retract the pad, place engineered cribbing of adequate size and strength, or relocate the truck to firm ground. Continuing setup on settling fill risks a tip-over once the load is lifted.

3What is the primary purpose of cribbing under outrigger pads on soft soil?

A.To reduce hydraulic pressure in the outrigger jack

B.To distribute the outrigger reaction over a larger bearing area

C.To raise the truck high enough to clear curbs

D.To electrically isolate the truck from the ground

Explanation: Cribbing (sometimes called mats, dunnage, or outrigger pads) increases the bearing area so that the pressure on the soil falls below the soil's allowable bearing capacity. It does not change the load — it spreads it across more square inches of ground.

4When setting up a digger derrick on a side slope, the manufacturer normally requires that the unit be:

A.Tilted to the downhill side to drain hydraulic fluid

B.Operated at a fixed 5-degree side slope at all times

C.Leveled within the manufacturer-specified tolerance, typically using outrigger length differences

D.Operated only when the boom faces directly uphill

Explanation: Load charts and stability calculations assume the digger derrick is level within the manufacturer's tolerance, often one to three degrees. The operator achieves this by extending outriggers to different lengths or by adding cribbing under the downhill side, never by ignoring the slope.

5The swing radius of a digger derrick refers to the:

A.Horizontal distance from the rotation centerline to the load hook

B.Vertical distance from the boom tip to the ground

C.Length of the auger when fully extended

D.Distance the outrigger pads project from the truck frame

Explanation: Swing or working radius is measured horizontally from the centerline of rotation to the load hook or lifted load. Radius drives the rated capacity on the load chart — as radius increases, capacity drops.

6Pinch points exist between the rotating superstructure and any nearby fixed object. The accepted control under OSHA is to:

A.Allow workers to pass through if they keep their hands at their sides

B.Barricade the swing radius or otherwise prevent worker entry into the rotation zone

C.Sound the horn once before each swing

D.Slow the swing to half speed when workers are visible

Explanation: OSHA requires the swing radius hazard area to be guarded so that workers cannot enter the area between the rotating superstructure and adjacent objects. Acceptable methods include barricades, fencing, or other physical means that prevent entry into the pinch-point zone.

7Under OSHA 1926.1408 Table A, the minimum approach distance for equipment operating near an unidentified-voltage line up to 50 kV is:

A.4 feet

B.6 feet

C.10 feet

D.15 feet

Explanation: Table A of 1926.1408 lists 10 feet as the minimum approach distance for power lines up to 50 kV. When the voltage is unknown but believed to be in that range, the 10-foot value is the conservative default for general construction work.

8Under OSHA 1926.1408 Table A, the minimum approach distance for a line rated over 50 kV up to 200 kV is:

A.10 feet

B.12 feet

C.15 feet

D.20 feet

Explanation: Table A increases the clearance from 10 feet (up to 50 kV) to 15 feet for lines above 50 kV through 200 kV. The exam typically expects the candidate to know the three lowest tiers of Table A clearances.

9Under OSHA 1926.1408 Table A, the minimum approach distance for a line rated over 200 kV up to 350 kV is:

A.15 feet

B.18 feet

C.20 feet

D.25 feet

Explanation: Table A specifies 20 feet of minimum clearance for lines over 200 kV through 350 kV. Voltages over 350 kV require larger clearances under separate rules in 1926.1410.

10If a digger derrick must operate closer than the Table A minimum approach distance under 1926.1408, the employer must:

A.Sign a waiver and proceed without further controls

B.Notify the utility, de-energize and ground the line, OR meet the requirements of 1926.1410 for energized work

C.Have only one ground worker present

D.Reduce the load to 50 percent of chart capacity

Explanation: OSHA prohibits encroachment inside the Table A distance unless the line is confirmed de-energized and visibly grounded, or the operation meets the strict requirements of 1926.1410 for working closer than Table A, which include utility involvement, dedicated spotters, insulating measures, and a written plan.

About the NCCCO Digger Derrick Exam

The NCCCO Digger Derrick Operator (DDO) certification is the recognized national credential for operators of digger derricks used to auger pole holes, set and remove poles, and handle materials for electric and telecommunication line work. The program includes both a written knowledge exam and a hands-on practical skills test on a digger derrick.

Assessment

Written exam of 75 multiple-choice questions covering site and setup, pre-operation, operation, technical knowledge, and manufacturers' load charts, plus a separate practical skills test on an actual digger derrick.

Time Limit

90 minutes written

Passing Score

75% on Core; 70% on specialty (standard NCCCO)

Exam Fee

Approximately $130 written + $135 practical (member rates) (National Commission for the Certification of Crane Operators (NCCCO))

NCCCO Digger Derrick Exam Content Outline

~18%

Site & Setup

Outrigger placement on rated ground, cribbing, slope tolerance, swing radius protection, MAD-driven power-line clearance, and equipotential bonding.

~16%

Pre-Operation Inspection

Daily inspection of boom, wire rope, hooks, hydraulics, outrigger pins, anti-two-block, boom angle indicator, pole guide, and load-chart availability.

~22%

Operation

Auger setup and recovery, pole grabber use, standing the pole through the guide, ANSI signaling, dual operations, tag lines, materials handling, and environmental limits.

~18%

Technical Knowledge

Load moment and stability, dynamic and shock loading, center of gravity, sling angles, working radius, rigging hitch capacities, and ANSI hand signals.

~14%

Manufacturers' Load Charts

Chart selection by configuration, working-radius lookup, net vs. gross capacity with rigging and attachments deducted, on-tires vs. on-outrigger charts.

~8%

OSHA / Regulatory

29 CFR 1926.1400(c)(4) exemption, scope of 1910.268 and 1926 subpart V, 1910.269 reference, 1926.1427 certification rule, signaling and operator-position rules.

~4%

Safety & Emergency

Line-strike survival, stay-in-cab and bunny-hop egress, ground worker control, MAD per 1926.1408, and post-incident inspection and removal from service.

How to Pass the NCCCO Digger Derrick Exam

What You Need to Know

Passing score: 75% on Core; 70% on specialty (standard NCCCO)
Assessment: Written exam of 75 multiple-choice questions covering site and setup, pre-operation, operation, technical knowledge, and manufacturers' load charts, plus a separate practical skills test on an actual digger derrick.
Time limit: 90 minutes written
Exam fee: Approximately $130 written + $135 practical (member rates)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

NCCCO Digger Derrick Study Tips from Top Performers

1Memorize OSHA Table A MAD values cold: 10 feet up to 50 kV, 15 feet over 50 up to 200 kV, and 20 feet over 200 up to 350 kV. These come up in multiple questions.

2Understand when the 1926.1400(c)(4) exemption applies (utility/telecom line work under 1910.268 or subpart V) and when 1926.1427 certification is required (general construction).

3Drill load-chart reading from at least two manufacturer charts; recognize boom length, working radius, outrigger configuration, on-tires, and over-front vs. over-side columns.

4Memorize that working radius is measured horizontally from the centerline of rotation to the load hook, not from the boom tip to the load.

5Practice converting between boom angle and working radius and learn the rule of using the next more restrictive value when the actual radius falls between two chart cells.

6Know the daily inspection items, especially wire rope (broken-wire counts), hydraulic hoses (bulges, leaks), outrigger pin retention, hook latch, anti-two-block device, and load chart legibility.

7Memorize standard ANSI hand signals for boom up/down, hoist up/down, swing, stop, and emergency stop (both arms extended horizontally, palms down, moved right and left).

8Practice the line-strike response narrative: stay in cab, warn others, call utility; if egress is forced, jump clear, land on both feet together, and shuffle or hop in small steps.

Frequently Asked Questions

How many questions are on the NCCCO Digger Derrick Operator written exam?

The NCCCO DDO Candidate Handbook specifies a 75-question multiple-choice written exam in 90 minutes. The candidate also has to pass a separate hands-on practical skills test on a digger derrick. Both written and practical must be passed within 12 months for certification.

What is the passing score for the NCCCO Digger Derrick exam?

NCCCO uses its standard scaled-score thresholds: 75% on the Core (when applicable) and 70% on the specialty exam. The DDO written exam follows the specialty threshold. Score reports are returned by NCCCO after testing.

How much does the NCCCO Digger Derrick certification cost?

Approximate fees are $130 for the written and $135 for the practical at NCCCO member rates, for a typical total around $265. Exact fees vary by test site and whether the candidate is sitting at a member or non-member rate; check the current Candidate Handbook for the current schedule.

Does OSHA require NCCCO DDO certification for utility line work?

Not always. Under 29 CFR 1926.1400(c)(4), digger derricks used to auger pole holes, set or remove poles, and handle materials for electric or telecommunication line work are exempt from subpart CC (and from the 1926.1427 operator-certification requirement) so long as the work is performed in compliance with 29 CFR 1910.268 or 1926 subpart V. Outside that scope — for example, general-construction lifts — the operator must be certified under 1926.1427, and NCCCO DDO is the most widely accepted credential.

What is the OSHA minimum approach distance for a digger derrick near power lines?

Under Table A of 29 CFR 1926.1408, the minimum approach distance (MAD) is 10 feet for lines up to 50 kV, 15 feet for lines over 50 kV up to 200 kV, and 20 feet for lines over 200 kV up to 350 kV. Inside utility-line work under subpart V or 1910.269, additional MAD tables and qualified-employee rules apply.

How long is the NCCCO certification valid?

NCCCO certifications are valid for 5 years. Recertification requires either re-examination or, in the manual track, documented operating experience plus continuing education and recertification testing per the current handbook.

Can the NCCCO DDO written exam be taken remotely?

No. NCCCO administers the DDO written and practical at accredited test sites with a proctor and certified practical examiner. Remote testing is not a current option for this program.