100+ Free AZ ROC C-11 Electrical (Commercial) Practice Questions

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Key Facts: AZ ROC C-11 Electrical (Commercial) Exam

110 Questions

Official Question Count

PSI Candidate Information Bulletin

240 Minutes

Time Limit

PSI Candidate Information Bulletin

70%

Passing Score

Arizona Registrar of Contractors

$66

Exam Fee

PSI Services LLC

NEC 2017 & NFPA 72 (2016)

Code Reference

PSI Outline Reference List (L-11.pdf)

NASCLA Electrical Accepted

Alternative Exam

Arizona ROC Licensing Board

100 Questions

Practice Question Bank

OpenExamPrep Practice Bank

The Arizona ROC C-11 Commercial Electrical Examination consists of 110 scored multiple-choice questions administered in a 240-minute (4-hour) open-book PSI computer-delivered session with a 70% passing score ($66 exam fee). This practice bank provides 100 realistic English-language practice questions with comprehensive NEC 2017 and NFPA 72 explanations adapted for trade study.

Sample AZ ROC C-11 Electrical (Commercial) Practice Questions

Try these sample questions to test your AZ ROC C-11 Electrical (Commercial) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A 480-volt, three-phase commercial feeder supplies a balanced load drawing 85 amperes at a power factor of 0.88 lagging. What is the total real power consumed by this three-phase load in kilowatts (kW)?

A.70.7 kW

B.62.2 kW

C.35.9 kW

D.40.8 kW

Explanation: The formula for real power in a balanced three-phase AC circuit is P = √3 × V_line × I_line × PF. Substituting the given values gives P = 1.73205 × 480 V × 85 A × 0.88 = 62,192.6 W, which rounds to 62.2 kW.

2A 480V, 3-phase, 3-wire branch circuit feeds a continuous load of 60 A over a distance of 250 feet. If THHN copper conductors with a circular mil area of 26,240 CM (1 AWG) are used, what is the calculated voltage drop assuming a K-factor of 12.9?

A.7.3 V

B.12.7 V

C.14.7 V

D.25.4 V

Explanation: For a three-phase circuit, voltage drop is calculated as VD = (√3 × K × I × L) / CM. Pluggng in the values: VD = (1.732 × 12.9 × 60 A × 250 ft) / 26,240 = 335,172 / 26,240 = 12.77 V (approximately 12.7 V), which is about 2.65% of 480V.

3In a 480Y/277-volt, 3-phase AC system, what is the peak-to-peak voltage of the line-to-neutral sinusoidal waveform?

A.391.7 V

B.678.8 V

C.554.0 V

D.783.5 V

Explanation: The RMS line-to-neutral voltage is 277 V. The peak voltage (V_peak) is 277 V × √2 = 277 × 1.4142 = 391.7 V. The peak-to-peak voltage is twice the peak voltage: 2 × 391.7 V = 783.5 V.

4A 75 kVA, 3-phase step-down transformer has a 480V delta primary and a 208Y/120V wye secondary. What is the maximum full-load secondary line current rating?

A.208.2 A

B.90.2 A

C.156.1 A

D.360.6 A

Explanation: For a three-phase transformer, secondary full-load current I_sec = kVA × 1000 / (√3 × V_line). Substituting: I_sec = (75 × 1000) / (1.732 × 208) = 75,000 / 360.256 = 208.2 A.

5A series circuit operating at 60 Hz contains a 15-ohm resistance, an inductive reactance of 25 ohms, and a capacitive reactance of 17 ohms. What is the total impedance (Z) of the circuit?

A.25.0 ohms

B.57.0 ohms

C.17.0 ohms

D.19.8 ohms

Explanation: Total impedance in a series RLC circuit is Z = √(R² + (X_L - X_C)²). Substituting: X_L - X_C = 25 - 17 = 8 ohms net inductive reactance. Z = √(15² + 8²) = √(225 + 64) = √289 = 17.0 ohms.

6Under NEC 2017 Table 220.12, what is the minimum unit load per square foot required when calculating the general lighting load for a commercial office building?

A.3.0 VA per sq ft

B.2.0 VA per sq ft

C.3.5 VA per sq ft

D.1.0 VA per sq ft

Explanation: NEC 2017 Table 220.12 specifies a minimum general lighting unit load of 3.5 VA per square foot for office buildings.

7When calculating the feeder load for commercial kitchen equipment under NEC 2017 Table 220.56, what demand factor is applied when four (4) commercial kitchen appliances are installed?

A.80%

B.100%

C.90%

D.70%

Explanation: NEC 2017 Table 220.56 lists demand factors for commercial electric cooking equipment: 1-2 units = 100%, 3 units = 90%, 4 units = 80%, 5 units = 70%, and 6 or more units = 65%. For 4 units, the demand factor is 80%.

8A commercial feeder supplies a continuous lighting load of 48 A and a non-continuous power load of 32 A. Under NEC 2017 Article 215.2(A)(1), what is the minimum required total ampacity rating of the feeder conductors?

A.80 A

B.100 A

C.92 A

D.108 A

Explanation: Under NEC 2017 Article 215.2(A)(1), feeder conductors must be sized to carry 125% of the continuous load plus 100% of the non-continuous load. Required Ampacity = (1.25 × 48 A) + 32 A = 60 A + 32 A = 92 A.

9Under NEC 2017 Article 230.24(A), service-drop conductors passing over a commercial roof with a slope of less than 4 inches in 12 inches must maintain a minimum vertical clearance of how many feet above the roof surface?

A.8 feet

B.3 feet

C.10 feet

D.12 feet

Explanation: NEC 2017 Section 230.24(A) requires overhead service conductors passing over a roof to maintain a vertical clearance of not less than 8 feet (2.44 m) above the roof surface. Exceptions exist for steep roofs (slope ≥ 4 in 12) or overhang terminations.

10Under NEC 2017 Article 230.95, ground-fault protection of equipment (GFPE) is mandatory for solid-grounded wye commercial electrical services operating at more than 150 volts to ground but not exceeding 600 volts phase-to-phase when the service disconnect rating is at least what ampere threshold?

A.800 amperes

B.1200 amperes

C.600 amperes

D.1000 amperes

Explanation: NEC 2017 Section 230.95 requires GFPE for each service disconnect rated 1000 amperes or more on solidly grounded wye electrical services operating at more than 150 volts to ground but not exceeding 600 volts phase-to-phase (e.g., 480Y/277V).

About the AZ ROC C-11 Electrical (Commercial) Exam

The Arizona ROC C-11 (or dual CR-11) Commercial Electrical Examination is a computer-delivered, open-book trade examination administered by PSI Services LLC for the Arizona Registrar of Contractors. The C-11 classification covers commercial electrical systems, including service feeders, three-phase power distribution, grounding and bonding, raceway sizing, hazardous locations, motors, transformers, fire alarm systems under NFPA 72 (2016), commercial photovoltaics (NEC 2017 Article 690), and OSHA construction safety. Candidates may substitute passing the NASCLA Accredited Examination for Commercial General Building Contractors or Electrical Contractors in lieu of this trade exam.

Questions

110 scored questions

Time Limit

240 minutes

Passing Score

70%

Exam Fee

$66 (Arizona ROC / PSI Services LLC)

AZ ROC C-11 Electrical (Commercial) Exam Content Outline

General Electrical Knowledge

Electrical theory, Ohm's law, Kirchhoff's laws, single-phase and three-phase AC power formulas, transformer principles, voltage drop calculations, and basic electrical formulas.

12%

Service Feeders and Branch Circuits

NEC Article 220 service load calculations, commercial building demand factors, feeder conductor sizing, multi-wire branch circuits, overhead/underground service clearances, GFCI protection in commercial spaces, and main disconnect rules.

12%

Grounding and Bonding

NEC Article 250 requirements, grounding electrode system (GEC sizing Table 250.66), equipment grounding conductors (EGC sizing Table 250.122), bonding jumpers, separately derived systems, main bonding jumpers, and structural metal/water pipe bonding.

11%

Conductors and Cables

NEC Table 310.15(B)(16) ampacity ratings, 75°C termination limits, ambient temperature correction, conduit fill derating, rooftop sunlight adjustment, Type MC, TC, and UF cable rules, and direct burial depths.

Raceways and Boxes

Conduit fill limits (40% rule), box volume calculations, pull box sizing for straight and angle pulls (NEC 314.28), support intervals for EMT, RMC, and PVC, expansion fittings, and box support rules.

12%

Special Occupancies and Equipment

Class I, II, III Hazardous (Classified) Locations (NEC 500-516), commercial garages, health care essential electrical systems (NEC 517), swimming pools (NEC 680), elevators (NEC 620), IT rooms (NEC 645), and fire pump feeder sizing (NEC 695).

Devices

Snap switch ratings, motor load switching, receptacle mounting standards, tamper-resistant and isolated ground receptacle applications (NEC 404 & 406).

Motors

NEC Article 430 motor branch-circuit sizing (125% FLC), overload protection sizing, short-circuit and ground-fault protection (Table 430.52), motor feeder sizing, and disconnect location/ratings.

Low Voltage

Class 1, 2, and 3 remote control and signaling circuits (NEC 725), separation from light/power conductors, communications systems (NEC 800), and Power over Ethernet (PoE) thermal limits.

Lighting

Luminaire recess clearances in insulated ceilings (Type IC vs non-IC), cord-and-plug connections, electric-discharge ballast disconnects, and LED/discharge lighting installation (NEC 410).

Illuminated Signs

Electric signs and outline lighting requirements (NEC 600), dedicated 20A branch circuit, disconnect switch within sight of sign, and bonding.

Fire Detection and Alarm Systems

NFPA 72 (2016 edition) standards, smoke detector spacing (30 ft grid), audible/visual notification appliance decibels and mounting heights, secondary power battery backup runtime, and PLFA fire alarm cable ratings (NEC 760).

Safety

OSHA 29 CFR 1926 standards for electrical safety, overhead power line clearances (10 ft minimum up to 50 kV), Lockout/Tagout procedures, Assured Equipment Grounding Conductor Program, trench excavation safety, and NFPA 70E arc flash PPE.

Overcurrent Protection

Small conductor overcurrent limits (NEC 240.4(D)), standard fuse/breaker ratings, feeder tap rules (10-ft and 25-ft tap rules), overcurrent device accessibility, series combination ratings, and arc energy reduction for ≥1200A breakers (NEC 240.87).

Photovoltaics

NEC Article 690 commercial PV installation, maximum current (125% Isc), conductor and OCPD sizing (156.25% Isc), rapid shutdown requirements (NEC 690.12), grounding electrode system, utility interconnection busbar 120% rule (NEC 705.12), and DC arc-fault protection.

How to Pass the AZ ROC C-11 Electrical (Commercial) Exam

What You Need to Know

Passing score: 70%
Exam length: 110 questions
Time limit: 240 minutes
Exam fee: $66

Keys to Passing

Work through all 100 available questions
Review every answer and explanation
Track weak areas and revisit them
Use our AI tutor for tough concepts

AZ ROC C-11 Electrical (Commercial) Study Tips from Top Performers

1Master commercial service and feeder load calculations under NEC Article 220, including demand factors for commercial kitchens, lighting, and general receptacles.

2Know NEC Table 310.15(B)(16) 75°C ampacities by heart, and practice applying temperature correction and conduit fill derating factors simultaneously.

3Review grounding and bonding rules in NEC Article 250, specifically Table 250.66 for Grounding Electrode Conductors (GEC) and Table 250.122 for Equipment Grounding Conductors (EGC).

4Study Commercial Photovoltaic System requirements in NEC Article 690, including the 125% current multiplier, rapid shutdown boundaries (690.12), and busbar 120% interconnection rules (705.12).

5Memorize NFPA 72 (2016) notification appliance mounting heights (80 to 96 inches) and smoke detector ceiling spacing (30-foot grid), along with OSHA 1926 10-foot power line safety clearances.

Frequently Asked Questions

How many questions are on the official Arizona ROC C-11 Commercial Electrical exam?

The official PSI C-11 Commercial Electrical trade exam contains 110 scored multiple-choice questions. Candidates are allotted 240 minutes (4 hours) to complete the test.

What passing score is required for the AZ ROC C-11 exam?

A minimum passing score of 70% (77 correct out of 110 questions) is required to pass the trade exam.

Which code editions are referenced on the Arizona C-11 exam?

The official PSI candidate bulletin (L-11.pdf) specifies NFPA 70 (National Electrical Code) 2017 Edition and NFPA 72 (National Fire Alarm and Signaling Code) 2016 Edition. Candidates should reference 2017 NEC code sections rather than later code cycles.

Can I use NASCLA Electrical in place of taking the AZ ROC C-11 exam?

Yes, Arizona accepts the NASCLA Accredited Examination for Electrical Contractors in lieu of taking the state-specific C-11 trade examination.

Is the Arizona ROC C-11 Commercial Electrical exam open book?

Yes, the examination is open-book. Approved references, including the NFPA 70 (NEC 2017), NFPA 72 (2016), and OSHA 29 CFR 1926, may be brought into the PSI testing center.

100+ Free AZ ROC C-11 Electrical (Commercial) Practice Questions

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