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Quizzes > Electronics & Gadgets

Industrial Electrician Practice Test

Quick, free industrial electrician test. Instant results.

Editorial: Review CompletedCreated By: Ahmet KutayUpdated Aug 28, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration for an Industrial Electrician Test quiz on a teal background.

This industrial electrician practice test helps you check control circuits, motor starters, wiring diagrams, and safety with real-world questions so you can spot gaps before an exam. For extra practice, try our electrical practice test, an electrical knowledge test, or an electronics knowledge test to round out your study.

According to Ohm's Law, how is current (I) calculated?
R = V × I
I = V / R
I = R / V
V = I × R
Ohm's Law defines the relationship between voltage, current, and resistance, stating that current equals voltage divided by resistance. This fundamental principle underpins most electrical circuit calculations and is essential for troubleshooting and design. Using I = V / R ensures accurate determination of current flow in a conductor under a known voltage and resistance. .
What is the standard unit of electrical voltage?
Volt
Ampere
Watt
Ohm
Voltage is measured in volts, which represent the potential difference between two points in an electrical circuit. It is one of the fundamental units in electrical engineering defined by the International System of Units (SI). Recognizing the correct unit is critical for reading specifications and performing accurate calculations. .
What is the main purpose of electrical conduit in industrial installations?
Protect and route electrical wiring
Store electrical energy
Increase circuit voltage
Reduce electrical current
Electrical conduit provides mechanical protection and support for conductors, shielding them from damage, moisture, and chemical exposure. It also helps organize and route wiring in complex industrial environments, ensuring safety and compliance with electrical codes. Proper use of conduit simplifies maintenance and reduces the risk of accidental shorts or physical abrasion. .
Which wire color is typically used for equipment grounding in the United States?
White
Black
Red
Green or green with yellow stripe
The National Electrical Code specifies green, or green with a yellow stripe, for equipment grounding conductors to ensure clear identification. This color coding helps electricians and inspectors quickly recognize grounding connections, which are essential for safe fault current paths. Using the correct color reduces the risk of improper wiring and electrical hazards. .
What is the primary function of a fuse in an electrical circuit?
Interrupt excessive current to protect equipment
Convert AC to DC
Filter electrical noise
Regulate voltage output
A fuse is a sacrificial overcurrent protection device that melts its internal element when the current exceeds its rating, opening the circuit and preventing damage to wiring and equipment. It reacts quickly to fault conditions, safeguarding downstream components. Proper fuse selection is critical to protecting industrial installations from short circuits and overloads. .
In a three-phase electrical system, how many voltage waveforms are phase-shifted by 120 degrees?
Two
Four
One
Three
A three-phase system consists of three alternating currents of equal frequency, each separated by a 120-degree phase shift. This arrangement provides a constant power transfer and is more efficient for industrial motors and heavy loads. Understanding the phase relationships is essential for system design and troubleshooting. .
Which of the following is a commonly used thermoplastic-insulated conductor designation?
ABC
RMC
THHN
MC
THHN stands for Thermoplastic High Heat-resistant Nylon-coated, a widely used conductor type in industrial and commercial wiring. It offers excellent insulation, heat resistance, and mechanical durability for most applications. Knowing conductor types and their ratings ensures compliance with code requirements. .
What is the purpose of a lockout/tagout procedure in industrial electrical work?
Improve power factor
Calibrate voltage measuring instruments
Prevent accidental energization during maintenance
Enhance arc flash protection
Lockout/tagout (LOTO) procedures ensure that electrical equipment is completely de-energized and cannot be re-energized while maintenance or repair work is performed. This practice prevents accidental startups that could cause injury or equipment damage. Compliance with OSHA and NFPA 70E standards requires strict LOTO protocols. .
A motor draws 50 A continuous. According to NEC, what minimum conductor ampacity should you select?
100 A
60 A
75 A
50 A
The NEC requires conductors supplying continuous loads to be sized at least 125% of the continuous current. Multiplying 50 A by 125% yields 62.5 A, so the next standard conductor size is 75 A. This ensures the conductor does not overheat under sustained load. .
What is the voltage drop across a conductor carrying 20 A with a resistance of 0.5 ??
10 ?
10 V
40 V
0.025 V
Voltage drop is calculated using V = I × R. With 20 A through 0.5 ?, the drop is 10 V. Managing voltage drop is important to maintain efficient operation of motors and other equipment in industrial installations. .
A single-phase transformer has 500 turns on the primary and 250 turns on the secondary. What is the voltage ratio?
1:2
1:1
2:1
4:1
Transformer voltage ratio equals the ratio of primary to secondary turns. With 500 primary turns and 250 secondary turns, the ratio is 500/250, or 2:1. This means the primary voltage is stepped down by half. .
According to NEC, what is the maximum conduit fill percentage when more than two conductors are installed?
60%
100%
40%
80%
The NEC specifies that when more than two conductors are placed in a conduit, the cross-sectional area of the conductors must not exceed 40% of the conduit's internal area. This rule ensures adequate space for heat dissipation and ease of pulling conductors. Overfilling can lead to overheating and difficulty in installation. .
Which device interrupts a circuit when it detects an imbalance between hot and neutral currents?
Arc Fault Circuit Interrupter (AFCI)
Thermal Magnetic Fuse (TMF)
Molded Case Circuit Breaker (MCCB)
Ground Fault Circuit Interrupter (GFCI)
A GFCI monitors the current balance between hot and neutral conductors. If it senses a difference, indicating current leakage to ground, it trips almost instantly to prevent shock. GFCIs are required in wet or hazardous locations. .
Which device is primarily used for remote switching of a motor circuit from a control panel?
Fuse
Transformer
Insulator
Contactor
Contactors are electromechanical switches designed to handle high current loads and provide remote control of motor circuits via control signals. They offer features like overload protection and auxiliary contacts for interlocking. Proper selection of contactors ensures reliable motor operation. .
In a Wye (star) three-phase configuration, which point provides the neutral connection?
Open leg
Delta corner
Common junction of the windings
Only in ungrounded systems
In a Wye configuration, one end of each of the three windings is connected together at a common point, which serves as the neutral. This neutral point can be grounded to stabilize system voltage and provide a return path. The configuration allows multiple voltage levels to be available. .
What does the acronym TEFC indicate on a motor nameplate?
Three-phase Enclosure Fault Controller
Thermal Electric Force Control
Totally Enclosed Fan Cooled
Totally Enclosed Free Circuit
TEFC stands for Totally Enclosed Fan Cooled, meaning the motor housing prevents free exchange of air between inside and outside and uses an external fan to cool the enclosure. This design protects against harsh environments, dust, and moisture. TEFC motors are common in industrial applications. .
What is the primary function of a Variable Frequency Drive (VFD) in motor control?
Provide uninterrupted backup power
Adjust motor speed by varying supply frequency
Increase supply voltage only
Convert direct current to alternating current only
A VFD controls motor speed and torque by converting incoming AC to DC and then inverting it back to AC at the desired frequency. Adjusting the output frequency allows precise speed control, energy savings, and reduced mechanical stress. VFDs are widely used in industrial pump and fan applications. .
What causes an arc flash hazard in electrical equipment?
Operation of thermal overload relays
Excessive neutral-to-ground voltage only
Low system impedance only
Ionized air forms a conductive path for fault current
An arc flash occurs when ionization of air creates a low-impedance path, allowing fault current to travel through air rather than the intended conductors. This can result in violent energy release, flames, and shrapnel. Proper PPE, barriers, and procedure compliance reduce the risk. .
In industrial power systems, what are harmonics?
Distortions in the voltage or current waveform caused by non-linear loads
Transient voltage sags only
Low-frequency mechanical vibrations
Pure sinusoidal waveforms at fundamental frequency
Harmonics are integer multiples of a system's fundamental frequency, created by non-linear loads such as VFDs and rectifiers. They distort waveforms, cause additional heating in equipment, and can lead to power quality issues. Mitigation involves filters or designing systems to tolerate harmonic currents. .
How does a synchronous motor maintain a constant speed under varying loads?
Through carbon brushes maintaining contact
By automatically varying supply voltage
Rotor magnetic field locks in step with the stator field
Using slip rings to adjust rotor current
A synchronous motor operates at a speed directly proportional to the supply frequency, with the rotor's field magnetically locked in phase with the stator's rotating magnetic field. This synchronization ensures constant speed regardless of load variations, within torque limits. They are used where precise speed is critical. .
What is the typical sequence of operations in a PLC scan cycle?
Read inputs, execute program logic, update outputs
Update outputs, read inputs, execute logic
Execute logic, update outputs, read inputs
Random order based on priority
A PLC scan cycle begins with reading the state of all inputs, then executing the user's control logic based on those inputs, and finally updating the outputs accordingly. This deterministic cycle ensures real-time control and predictable response times. Proper understanding of scan timing is crucial for reliable automation. .
What is the purpose of a grounding electrode conductor (GEC)?
Carry normal operational current
Connect the grounding system to the earth electrode for safety
Insulate conductors from moisture
Serve as the circuit neutral
The GEC bonds the electrical system to earth, stabilizing voltage during normal operation and limiting overvoltages during lightning or faults. It provides a low-impedance path for fault currents, ensuring protective devices operate properly. Proper grounding is critical for safety and equipment protection. .
Motor overload protection should typically be sized at what percentage of the motor's full-load current?
100%
80%
115%
150%
Motor overload relays are commonly set to 115% of the motor's full-load current to allow for normal starting currents while protecting against sustained overloads. This percentage provides a balance between avoiding nuisance trips and preventing motor damage from overheating. Manufacturer curves and NEC guidelines inform final settings. .
In a per-unit system, what is the base current for a 100 MVA, 13.8 kV system?
? 4,183 A
? 2,300 A
? 1,000 A
? 15,000 A
Base current in per-unit calculations is Sbase divided by (?3 × Vbase). For 100 MVA and 13.8 kV: Ib = 100×10? / (1.732×13,800) ? 4,183 A. This normalization simplifies fault and steady-state analyses. .
In a PID controller, what primary issue does the integral term address?
Increases proportional response
Eliminates steady-state error
Filters measurement noise
Reduces system overshoot only
The integral component accumulates the error over time and adjusts the output to eliminate any persistent deviation between setpoint and process variable. This action removes steady-state offsets that the proportional term alone cannot correct. PID tuning balances all three terms for optimal control response. .
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Study Outcomes

  1. Understand Key Industrial Electrical Concepts -

    You will grasp fundamental principles of industrial electrical engineering, including power distribution, circuit design, and safety standards.

  2. Analyze Wiring Diagrams and Control Circuits -

    You will be able to interpret and troubleshoot complex wiring schematics commonly featured in industrial electrician practice tests and real-world applications.

  3. Apply Troubleshooting Techniques -

    You will develop systematic approaches to diagnose and resolve faults in motors, drives, and control panels using methods tested in the quiz.

  4. Interpret Industrial Electrical Controls -

    You will learn to read and evaluate control logic diagrams and PLC programs as covered in the industrial electrical controls quiz section.

  5. Prepare for Certification Exams -

    You will gain confidence and readiness for professional certification by reinforcing knowledge through the industrial electrician certification quiz.

Cheat Sheet

  1. Three-Phase Power Calculations -

    Master the IEEE-standard formula P = √3 × VLL × IL × cos φ for balanced three-phase systems. For example, a 480 V system drawing 30 A at a 0.8 power factor delivers P = √3 × 480 × 30 × 0.8 ≈ 19.95 kW. Use the mnemonic "VIP Cos φ" (Voltage, Current, Power factor) to recall the key parameters.

  2. Motor Control Circuit Fundamentals -

    Review NEMA-rated contactors and thermal overload relays in forward/reverse and star-delta starters to recognize common control schemes. Star-delta starting reduces inrush current to one-third of direct-on-line (DOL) startups, per IEC guidelines. Practice interpreting ladder diagrams to spot coils, NO/NC contacts, and interlock circuits.

  3. PLC Scan Cycle & Ladder Logic -

    Understand the PLC scan cycle - Input scan, Logic solve, and Output update - and how ladder diagrams map real-world devices to contacts and coils. A typical START/STOP rung uses an NO start pushbutton in series with an NC stop pushbutton plus a seal-in contact for hold-in operation. Remember "I-S-O" (Inputs, Solve, Outputs) to sequence the scan process.

  4. Electrical Safety & Lockout/Tagout (LOTO) -

    Follow OSHA 1910.147's five steps - prepare, shutdown, isolate, lock/tag, verify - to achieve a zero-energy state before maintenance. Memorize "Pull Shut Isolate Lock Verify" to ensure no step is missed. Review NIOSH case studies for real-world LOTO examples and best practices.

  5. Reading Wiring & Single-Line Diagrams -

    Differentiate schematic vs wiring vs single-line diagrams: schematics show functional relationships, wiring diagrams detail actual cable runs, and single-line diagrams depict overall power flow. Note terminal numbers (e.g., T1 - T2 for starter coils) and IEC color codes (black L1, brown L2, grey L3). Trace a simple motor starter diagram to sharpen your skills.

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