100+ Free AZ ROC A-17 Electrical and Transmission Lines Practice Questions

Prepare for the Arizona ROC A-17 Electrical and Transmission Lines (Commercial) Examination exam with instant access — no signup required.

✓ No registration✓ No credit card✓ No hidden fees✓ Start practicing immediately

100+ Questions

100% Free

Loading practice questions...

Same family resources

Explore More Arizona Registrar of Contractors Trade Examinations

Continue into nearby exams from the same family. Each card keeps practice questions, study guides, flashcards, videos, and articles in one place.

2026 Statistics

Key Facts: AZ ROC A-17 Electrical and Transmission Lines Exam

Scored Exam Questions

PSI Candidate Bulletin

225 Min

Time Allotted

PSI Candidate Bulletin

70%

Passing Score (63/90)

AZ ROC / PSI

$66

Trade Exam Fee

PSI Testing

Open-Book

Test Format

PSI Services LLC

11 Topics

Blueprint Subject Areas

AZ ROC A-17 Outline

The Arizona ROC A-17 Commercial Electrical and Transmission Lines exam consists of 90 scored computer-delivered questions administered open-book by PSI with a 225-minute time limit and a 70% passing threshold ($66 fee). Topics span high-voltage transmission lines, sub-stations, transformers, conductors, grounding, underground/overhead lines, gear over 600V, equipment safety, and commercial PV systems. Note: Local practice MCQs are an English-language study adaptation designed to reinforce code navigation and technical calculations, and do not replace hands-on field experience or official board approval.

Sample AZ ROC A-17 Electrical and Transmission Lines Practice Questions

Try these sample questions to test your AZ ROC A-17 Electrical and Transmission Lines exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A 3-phase, 480 V commercial distribution line serves an inductive motor load drawing a line current of 120 A. What is the total apparent power (S) delivered to the load?

A.99.8 kVA

B.57.6 kVA

C.172.8 kVA

D.143.6 kVA

Explanation: In a balanced three-phase system, apparent power is calculated using the formula S = √3 × V_L × I_L. Substituting the values gives S = 1.73205 × 480 V × 120 A = 99,766 VA = 99.8 kVA.

2An industrial facility operates a 3-phase load consuming 400 kW of active real power (P) at a lagging power factor of 0.80. What is the reactive power (Q) in kVAR drawn by this facility?

A.500 kVAR

B.300 kVAR

C.240 kVAR

D.320 kVAR

Explanation: With a power factor cos(θ) = 0.80, the phase angle θ = arccos(0.80) = 36.87°. Apparent power S = P / cos(θ) = 400 kW / 0.80 = 500 kVA. Reactive power Q = √(S² - P²) = √(500² - 400²) = 300 kVAR (or Q = P × tan(36.87°) = 400 × 0.75 = 300 kVAR).

3A 60 Hz high-voltage overhead transmission line has a series inductance of 1.5 mH per mile per phase. What is the inductive reactance (X_L) per mile of this line?

A.0.094 Ω/mile

B.0.283 Ω/mile

C.0.565 Ω/mile

D.0.754 Ω/mile

Explanation: Inductive reactance is calculated using X_L = 2 × π × f × L. For a 60 Hz system with L = 1.5 mH/mile = 0.0015 H/mile: X_L = 2 × 3.14159 × 60 × 0.0015 = 0.5655 Ω/mile (approximately 0.565 Ω/mile).

4In a balanced 3-phase Delta-connected distribution system, what is the relationship between the line voltage (V_L) and the phase winding voltage (V_P)?

A.Line voltage is √3 times phase voltage

B.Line voltage is 1/3 of phase voltage

C.Line voltage is 3 times phase voltage

D.Line voltage is equal to phase voltage

Explanation: In a Delta connection, each phase winding is connected directly across two line conductors. Therefore, line voltage is equal to phase voltage (V_L = V_P), while line current is √3 times the phase winding current (I_L = √3 × I_P).

5In a balanced 3-phase Wye (Star) connected distribution circuit, how does the line current (I_L) compare to the phase winding current (I_P)?

A.Line current is equal to phase current

B.Line current is √3 times phase current

C.Line current is 1/√3 of phase current

D.Line current is 3 times phase current

Explanation: In a Wye connection, line conductors are connected in series with each phase winding. Consequently, the line current is equal to the phase current (I_L = I_P), whereas line voltage is √3 times phase voltage (V_L = √3 × V_P).

6A 69 kV 3-phase sub-transmission line is designed for a maximum allowable voltage drop of 5.0% under full load. What is the minimum receiving-end line-to-line voltage permitted?

A.62.10 kV

B.65.55 kV

C.68.00 kV

D.64.00 kV

Explanation: A 5.0% voltage drop on a 69 kV line means the line retains 95.0% of its nominal sending-end voltage. Minimum receiving voltage = 69 kV × (1 - 0.05) = 69 kV × 0.95 = 65.55 kV.

7What phenomenon causes high-frequency or large-diameter AC transmission line conductors to exhibit higher effective resistance to AC current than to DC current?

A.Proximity effect

B.Corona discharge

C.Skin effect

D.Ferranti effect

Explanation: Skin effect is the tendency of alternating electrical current (AC) to distribute itself within a conductor such that the current density is highest near the outer surface and decreases with greater depths. This reduces the effective cross-sectional area of the conductor, thereby increasing its effective AC resistance compared to DC.

8Applying Kirchhoff's Current Law (KCL) to a substation main bus node, three incoming supply feeders deliver 150 A, 220 A, and 180 A of current at a given instant. Assuming no other connections, what is the total current leaving the bus node through outgoing distribution feeders?

A.220 A

B.370 A

C.400 A

D.550 A

Explanation: Kirchhoff's Current Law states that the algebraic sum of currents entering a node must equal the algebraic sum of currents leaving the node. Total incoming current = 150 A + 220 A + 180 A = 550 A. Therefore, total outgoing current must equal 550 A.

9In a series RLC AC circuit representing a transmission line segment, under what condition does electrical resonance occur?

A.Inductive reactance equals capacitive reactance (X_L = X_C)

B.Resistance equals inductive reactance (R = X_L)

C.Total impedance reaches its maximum value

D.Power factor becomes 0.0 leading

Explanation: Series resonance occurs when inductive reactance equals capacitive reactance (X_L = X_C). At resonance, the inductive and capacitive reactances cancel each other out (Z = R), resulting in a purely resistive circuit with unity power factor (1.0) and minimum total impedance.

10A 13.8 kV 3-phase distribution feeder supplies a commercial load with a line current of 200 A at a power factor of 0.90 lagging. What is the active real power (P) delivered in megawatts (MW)?

A.2.48 MW

B.4.30 MW

C.4.78 MW

D.7.45 MW

Explanation: Active real power P = √3 × V_L × I_L × PF. P = 1.73205 × 13,800 V × 200 A × 0.90 = 4,301,616 W = 4.30 MW.

About the AZ ROC A-17 Electrical and Transmission Lines Exam

The Arizona ROC A-17 Electrical and Transmission Lines commercial examination tests prospective contractors on the installation, alteration, repair, and maintenance of high-voltage transmission lines, sub-transmission networks, electrical supply stations, distribution transformers, overhead and underground distribution systems, grounding, medium- and high-voltage gear, equipment over 600 volts, and commercial utility-scale photovoltaic installations. Administered open-book by PSI Services LLC, candidates must correctly answer at least 63 of 90 questions (70%) in 225 minutes.

Questions

90 scored questions

Time Limit

225 minutes

Passing Score

70%

Exam Fee

$66 (Arizona ROC / PSI Services LLC)

AZ ROC A-17 Electrical and Transmission Lines Exam Content Outline

11%

General Electrical Knowledge

AC/DC principles, Ohm's/Kirchhoff's laws, power factor, three-phase power calculations, circuit analysis, line losses.

11%

Transformers

Single-phase and three-phase transformers, delta/wye connections, autotransformers, turns ratios, impedance, parallel operation, oil-immersed vs dry-type.

11%

Conductors

ACSR, AAC, AAAC overhead conductors, underground MV cable insulation, ampacity, voltage drop, skin effect, tension, sag calculations.

Grounding Methods

Equipment grounding, system grounding, counterpoise systems, substation grounding grids, bonding, ground resistance testing.

Poles and Structures

Wood, steel, concrete poles, lattice towers, guy wires and anchors, pole setting depth, crossarms, insulators, guy tensioning.

Underground Lines

Direct burial cable, duct banks, manholes, splice vaults, elbow terminations, stress cones, trench depth, backfill requirements.

Overhead Lines

Line routing, span lengths, clearance over roadways/railroads/waterways, stringing, sag tables, armor rods, vibration dampers.

Equipment over 600 Volts

Medium & high-voltage switchgear, circuit breakers, reclosers, sectionalizers, metal-enclosed gear, potential and current transformers (PTs/CTs).

Electrical Supply Stations

Substation layouts, bus structures, lightning arresters, isolation switches, transformer bays, oil containment, fence grounding.

11%

Equipment and Safety

OSHA 1910.269 & 1926 Subpart V, hot line tools, personal protective grounding, bucket trucks, crane clearances, PPE classes, arc flash safety.

11%

Photovoltaics

Commercial & utility-scale PV array wiring, string inverters, central inverters, rapid shutdown, DC/AC disconnects, NEC Article 690 & 705 requirements.

How to Pass the AZ ROC A-17 Electrical and Transmission Lines Exam

What You Need to Know

Passing score: 70%
Exam length: 90 questions
Time limit: 225 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 A-17 Electrical and Transmission Lines Study Tips from Top Performers

1Master high-voltage formula calculations for voltage drop, three-phase apparent power (S = √3 × V × I), transformer turns ratios, and conductor sag.

2Tab index approved references such as NFPA 70 (NEC Articles 250, 300, 310, 450, 490, 690, 705), NESC Section 23 (Clearances), and NESC Section 9 (Grounding).

3Familiarize yourself with OSHA 1910.269 and 1926 Subpart V safety regulations, specifically minimum approach distances (MAD), personal protective grounding, and hot-stick usage.

4Review utility substation component functions including PTs, CTs, SF6 circuit breakers, lightning arresters, and counterpoise grounding.

5Pace yourself during the 225-minute test: spend about 2 to 2.5 minutes per question, leaving time to verify reference lookup questions.

Frequently Asked Questions

What is covered on the Arizona ROC A-17 examination?

The A-17 commercial exam covers installation, maintenance, and repair of overhead and underground electrical transmission lines, distribution circuits, substations, high-voltage equipment over 600V, power transformers, grounding networks, pole structures, line hardware, OSHA high-voltage safety standards, and utility-scale PV systems.

Is the AZ ROC A-17 exam open-book?

Yes. The examination is open-book and administered on computer at PSI test centers. Permitted references include the National Electrical Code (NFPA 70), National Electrical Safety Code (IEEE C2), Lineman's and Cableman's Handbook, and OSHA 1910.269/1926 Subpart V safety regulations.

How many questions are on the exam and what is the passing score?

The official exam contains 90 scored multiple-choice questions. Candidates are allotted 225 minutes (3 hours 45 minutes) and must achieve a minimum score of 70% (63 correct answers) to pass.

What is the fee for taking the A-17 exam?

The examination fee for the A-17 trade portion is $66, payable directly to PSI Services LLC upon scheduling.

How does the practice question bank compare to the actual PSI exam?

This practice question bank contains 100 high-quality multiple-choice questions mapped strictly to the official PSI blueprint percentages. It provides detailed explanations citing relevant codes (NEC, NESC, OSHA) and calculations to reinforce trade mastery.

100+ Free AZ ROC A-17 Electrical and Transmission Lines Practice Questions

Explore More Arizona Registrar of Contractors Trade Examinations

Arizona ROC A (KA) Dual Engineering Examination

Arizona ROC A General Engineering (Commercial) Examination

Arizona ROC A-11/CR-17/R-17 Steel and Aluminum Erection Examination

Arizona ROC A-12/CR-80 Sewers, Drains and Pipe Laying Examination

Arizona ROC A-14 Asphalt Paving Examination

Arizona ROC A-15 Seal Coating Examination