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UT Electrician practice questions

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Question 1General Electrical Knowledge and National Electrical Code Structure

Which formula correctly expresses Ohm's law for a DC circuit?

  1. I = V × R
  2. R = V × I
  3. V = I / R
  4. V = I × R Correct answer.

Explanation

Ohm's law states that voltage equals current multiplied by resistance. The valid rearrangements are I = V / R and R = V / I.

Question 2General Electrical Knowledge and National Electrical Code Structure

In a series circuit, which quantity is the same through every component?

  1. Resistance
  2. Power
  3. Current Correct answer.
  4. Voltage

Explanation

A series circuit has only one path for current, so the same current flows through every component. Voltage drops and power dissipation can differ depending on each component's resistance.

Question 3General Electrical Knowledge and National Electrical Code Structure

Which NEC article contains the definitions of terms used throughout the Code?

  1. Article 250
  2. Article 200
  3. Article 100 Correct answer.
  4. Article 210

Explanation

Article 100, located in Chapter 1, provides the definitions of terms used throughout the National Electrical Code.

Question 4General Electrical Knowledge and National Electrical Code Structure

Conductor fill tables for raceways are located in which NEC chapter?

  1. Chapter 3
  2. Chapter 2
  3. Chapter 9 Correct answer.
  4. Chapter 7

Explanation

Chapter 9 contains the standard tables, including raceway and tubing fill tables and conductor properties. Chapters 2, 3, and 7 contain articles on wiring and protection, wiring methods, and special conditions.

Question 5General Electrical Knowledge and National Electrical Code Structure

In the NEC, what does the word "shall" indicate?

  1. An informational note
  2. A mandatory requirement Correct answer.
  3. An optional allowance
  4. A recommended practice

Explanation

The NEC uses "shall" to indicate a mandatory requirement. Permissive allowances generally use "shall be permitted" or "may," while informational notes are nonmandatory explanatory text.

Question 6General Electrical Knowledge and National Electrical Code Structure

What is the standard frequency of alternating current in the United States?

  1. 120 Hz
  2. 50 Hz
  3. 400 Hz
  4. 60 Hz Correct answer.

Explanation

US electric power systems operate at a standard frequency of 60 Hz. A frequency of 50 Hz is common in many other countries, and 400 Hz is used in specialized equipment such as aircraft.

Question 7General Electrical Knowledge and National Electrical Code Structure

A dwelling unit's general-purpose lighting and receptacle outlets are supplied by branch circuits. Which NEC article governs branch-circuit requirements?

  1. Article 210 Correct answer.
  2. Article 230
  3. Article 215
  4. Article 225

Explanation

Article 210 contains the requirements for branch circuits. Article 215 covers feeders, Article 225 covers outside branch circuits and feeders, and Article 230 covers services.

Question 8General Electrical Knowledge and National Electrical Code Structure

An electrician is installing a grounding electrode system for a new service. Which NEC article provides the requirements?

  1. Article 240
  2. Article 250 Correct answer.
  3. Article 230
  4. Article 200

Explanation

Article 250 contains the requirements for grounding and bonding, including grounding electrode systems. Article 200 covers grounded conductors, Article 230 covers services, and Article 240 covers overcurrent protection.

Question 9General Electrical Knowledge and National Electrical Code Structure

A 40-horsepower, three-phase motor is being installed with overload protection. Which NEC article applies?

  1. Article 440
  2. Article 430 Correct answer.
  3. Article 455
  4. Article 445

Explanation

Article 430 covers motors, motor circuits, and controllers, including motor overload protection. Article 440 covers air-conditioning and refrigerating equipment, Article 445 covers generators, and Article 455 covers phase converters.

Question 10General Electrical Knowledge and National Electrical Code Structure

A homeowner is installing a spa with a recirculating pump and underwater luminaire. Which NEC article contains the specific rules?

  1. Article 682
  2. Article 422
  3. Article 680 Correct answer.
  4. Article 690

Explanation

Article 680 contains the special requirements for swimming pools, spas, hot tubs, and fountains. Article 422 covers appliances, Article 682 covers bodies of water, and Article 690 covers photovoltaic systems.

Question 11General Electrical Knowledge and National Electrical Code Structure

A roof-mounted photovoltaic array is being connected to a building's electrical system. Which NEC article covers photovoltaic systems?

  1. Article 705
  2. Article 692
  3. Article 694
  4. Article 690 Correct answer.

Explanation

Article 690 contains the requirements for solar photovoltaic systems. Article 692 covers fuel cells, Article 694 covers wind electric systems, and Article 705 covers interconnected power production sources.

Question 12General Electrical Knowledge and National Electrical Code Structure

Emergency systems that supply power for life safety, such as egress lighting, are covered by which NEC article?

  1. Article 700 Correct answer.
  2. Article 701
  3. Article 702
  4. Article 695

Explanation

Article 700 covers emergency systems, including power and lighting for life safety. Article 701 covers legally required standby systems, Article 702 covers optional standby systems, and Article 695 covers fire pumps.

Question 13General Electrical Knowledge and National Electrical Code Structure

For a purely resistive single-phase load, which formula gives power?

  1. P = I / V
  2. P = V × I × R
  3. P = V / I
  4. P = V × I Correct answer.

Explanation

In a resistive DC or single-phase AC circuit, power in watts equals voltage multiplied by current. Other valid forms include P = I²R and P = V²/R.

Question 14General Electrical Knowledge and National Electrical Code Structure

In a parallel circuit, which quantity is the same across each branch?

  1. Power
  2. Resistance
  3. Current
  4. Voltage Correct answer.

Explanation

Parallel branches are connected across the same two nodes, so the voltage across each branch is equal. Branch currents can differ according to each branch's resistance.

Question 15General Electrical Knowledge and National Electrical Code Structure

For a conductor of fixed material and temperature, resistance increases when which of the following occurs?

  1. The cross-sectional area increases
  2. The length decreases
  3. The length increases Correct answer.
  4. The conductor diameter increases

Explanation

Conductor resistance is directly proportional to length and inversely proportional to cross-sectional area. Increasing length raises resistance, while increasing area or diameter lowers it.

Question 16General Electrical Knowledge and National Electrical Code Structure

Wall-mounted snap switches in a commercial building are covered by which NEC article?

  1. Article 400
  2. Article 404 Correct answer.
  3. Article 406
  4. Article 402

Explanation

Article 404 covers switches, including snap switches. Article 406 covers receptacles, Article 402 covers fixture wires, and Article 400 covers flexible cords and cables.

Question 17General Electrical Knowledge and National Electrical Code Structure

A utility-interactive inverter is being connected to a building's service. Which NEC article covers interconnected electric power production sources?

  1. Article 690
  2. Article 694
  3. Article 705 Correct answer.
  4. Article 692

Explanation

Article 705 covers interconnected electric power production sources operating in parallel with primary power sources. Article 690 covers photovoltaic systems, Article 692 covers fuel cells, and Article 694 covers wind systems.

Question 18General Electrical Knowledge and National Electrical Code Structure

A Code rule states that an installation "shall be permitted." How should this be interpreted?

  1. As a prohibition
  2. As an informational note
  3. As a permissive allowance Correct answer.
  4. As a mandatory requirement

Explanation

The phrase "shall be permitted" allows an installation but does not require it. A mandatory rule uses "shall," a prohibition uses "shall not," and informational notes are nonmandatory guidance.

Question 19General Electrical Knowledge and National Electrical Code Structure

In Article 100, what does "listed" mean?

  1. Published in a testing laboratory's list Correct answer.
  2. Marked with the manufacturer's nameplate
  3. Approved by the authority having jurisdiction
  4. Inspected by the installing electrician

Explanation

Listed equipment is included in a list published by an organization acceptable to the authority having jurisdiction that evaluates products and maintains periodic inspection. "Labeled" refers to equipment bearing a label or mark.

Question 20General Electrical Knowledge and National Electrical Code Structure

Class 2 and Class 3 remote-control and signaling circuits are covered by which NEC article?

  1. Article 720
  2. Article 727
  3. Article 760
  4. Article 725 Correct answer.

Explanation

Article 725 covers Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits. Article 760 covers fire alarm systems, Article 727 covers instrument tray cable, and Article 720 covers circuits operating at less than 50 volts.

Question 21Electrical Calculations and Theory

A 24-volt DC source is connected across a resistor of 8 ohms. What current flows in the circuit?

  1. 0.33 A
  2. 12 A
  3. 3 A Correct answer.
  4. 192 A

Explanation

Ohm's law states that current equals voltage divided by resistance, so I = 24 V / 8 Ω = 3 A.

Question 22Electrical Calculations and Theory

A 120-volt resistive load draws 15 amperes. How much power does the load consume?

  1. 1800 W Correct answer.
  2. 900 W
  3. 135 W
  4. 8 W

Explanation

For a resistive load, power equals voltage multiplied by current: P = 120 V × 15 A = 1800 W.

Question 23Electrical Calculations and Theory

Three resistors rated 6 ohms, 9 ohms, and 15 ohms are connected in series. What is the total resistance of the combination?

  1. 30 Ω Correct answer.
  2. 2.9 Ω
  3. 3.75 Ω
  4. 10 Ω

Explanation

In a series circuit the resistances add directly: 6 + 9 + 15 = 30 Ω.

Question 24Electrical Calculations and Theory

Two 12-ohm resistors are connected in parallel. What is the equivalent resistance of the pair?

  1. 6 Ω Correct answer.
  2. 0.083 Ω
  3. 1.2 Ω
  4. 24 Ω

Explanation

For two equal resistors in parallel, the equivalent resistance is half of one resistor: 12 / 2 = 6 Ω. The general form is 1/RT = 1/12 + 1/12.

Question 25Electrical Calculations and Theory

If the length of a conductor is doubled while its cross-sectional area and temperature remain unchanged, its resistance will:

  1. quadruple
  2. be halved
  3. double Correct answer.
  4. remain the same

Explanation

Resistance is directly proportional to length (R = ρL/A), so doubling the length doubles the resistance when area and temperature are held constant.

Question 26Electrical Calculations and Theory

A sinusoidal voltage has an RMS value of 120 volts. What is its peak value?

  1. 120 V
  2. 85 V
  3. 170 V Correct answer.
  4. 240 V

Explanation

For a sine wave, peak value equals RMS value multiplied by √2, so 120 × 1.414 ≈ 170 V.

Question 27Electrical Calculations and Theory

What is the period of a 60-hertz sine wave?

  1. 16.7 ms Correct answer.
  2. 0.0167 ms
  3. 60 s
  4. 0.6 s

Explanation

Period is the reciprocal of frequency: 1 / 60 Hz ≈ 0.0167 second, which equals 16.7 milliseconds.

Question 28Electrical Calculations and Theory

A 6-ohm resistor is connected in series with a parallel pair made up of two 8-ohm resistors. What is the total resistance of the circuit?

  1. 22 Ω
  2. 10 Ω Correct answer.
  3. 14 Ω
  4. 2.4 Ω

Explanation

The two 8-ohm resistors in parallel equal 4 Ω. Adding that to the 6-ohm series resistor gives 6 + 4 = 10 Ω.

Question 29Electrical Calculations and Theory

At a junction, 8 amperes enter through one conductor and 3 amperes leave through a second conductor. What current must leave through the only remaining conductor?

  1. 5 A Correct answer.
  2. 24 A
  3. 2.67 A
  4. 11 A

Explanation

Kirchhoff's current law requires that current entering a junction equal current leaving it, so 8 − 3 = 5 A must leave on the remaining conductor.

Question 30Electrical Calculations and Theory

A load draws 10 kW at a power factor of 0.8. What is the apparent power drawn by the load?

  1. 16 kVA
  2. 12.5 kVA Correct answer.
  3. 10.8 kVA
  4. 8 kVA

Explanation

Apparent power equals real power divided by power factor: 10 kW / 0.8 = 12.5 kVA.

Question 31Electrical Calculations and Theory

A balanced three-phase load draws 20 amperes per line at 480 volts with a power factor of 0.9. What is the real power consumed?

  1. 16.6 kW
  2. 18.7 kW
  3. 15.0 kW Correct answer.
  4. 8.6 kW

Explanation

Real power in a balanced three-phase circuit is P = √3 × E × I × PF, so 1.732 × 480 × 20 × 0.9 ≈ 15.0 kW.

Question 32Electrical Calculations and Theory

A transformer has 480 turns on its primary and 120 turns on its secondary. If 240 volts is applied to the primary, what voltage appears across the secondary?

  1. 960 V
  2. 60 V Correct answer.
  3. 180 V
  4. 120 V

Explanation

The turns ratio is 480:120, or 4:1, and a transformer steps voltage down by that same ratio: 240 / 4 = 60 V.

Question 33Electrical Calculations and Theory

A single-phase 120-volt branch circuit carries 10 amperes through conductors whose total resistance, out and back, is 0.4 ohm. What is the voltage drop on the circuit?

  1. 0.4 V
  2. 4 V Correct answer.
  3. 2 V
  4. 48 V

Explanation

Voltage drop equals current times total conductor resistance: 10 A × 0.4 Ω = 4 V.

Question 34Electrical Calculations and Theory

What is the inductive reactance of a 0.1-henry inductor connected to a 60-hertz source?

  1. 0.06 Ω
  2. 6 Ω
  3. 37.7 Ω Correct answer.
  4. 377 Ω

Explanation

Inductive reactance is XL = 2πfL = 2π × 60 × 0.1 ≈ 37.7 Ω.

Question 35Electrical Calculations and Theory

A 50-microfarad capacitor is connected to a 60-hertz source. What is its capacitive reactance?

  1. 265 Ω
  2. 18.8 Ω
  3. 0.019 Ω
  4. 53.1 Ω Correct answer.

Explanation

Capacitive reactance is XC = 1/(2πfC) = 1/(2π × 60 × 0.00005) ≈ 53.1 Ω.

Question 36Electrical Calculations and Theory

A 6-ohm resistor is connected in series with an inductor having 8 ohms of inductive reactance. What is the impedance of the combination?

  1. 2 Ω
  2. 14 Ω
  3. 10 Ω Correct answer.
  4. 48 Ω

Explanation

Resistance and reactance add at a 90-degree phase angle, so Z = √(6² + 8²) = √100 = 10 Ω.

Question 37Electrical Calculations and Theory

A 120-volt source supplies two parallel branches: one is a 30-ohm resistor, and the other is a 60-ohm resistor. What total power is dissipated by both branches?

  1. 160 W
  2. 480 W
  3. 720 W Correct answer.
  4. 240 W

Explanation

Each branch sees the full 120 V, so P = 120²/30 + 120²/60 = 480 W + 240 W = 720 W.

Question 38Electrical Calculations and Theory

In a balanced three-phase, four-wire wye system serving linear loads, the current in the neutral conductor is:

  1. zero Correct answer.
  2. equal to the line current
  3. one-third of the line current
  4. 1.732 times the line current

Explanation

The three phase currents are equal in magnitude and displaced by 120 degrees, so their phasor sum is zero. The neutral therefore carries current only when the system is unbalanced or harmonic-rich.

Question 39Electrical Calculations and Theory

A 1500-watt heater operates for 4 hours. How much energy does it consume?

  1. 600 kWh
  2. 6 kWh Correct answer.
  3. 0.375 kWh
  4. 60 kWh

Explanation

Energy in kilowatt-hours equals kilowatts times hours: 1.5 kW × 4 h = 6 kWh.

Question 40Electrical Calculations and Theory

What is the synchronous speed of a four-pole induction motor supplied at 60 hertz?

  1. 900 rpm
  2. 3600 rpm
  3. 1800 rpm Correct answer.
  4. 1200 rpm

Explanation

Synchronous speed is ns = 120f / P = (120 × 60) / 4 = 1800 rpm.

Question 41Electrical Calculations and Theory

A series RLC circuit contains a 25-ohm resistor, an inductor with 40 ohms of reactance, and a capacitor with 40 ohms of reactance. At resonance, what is the circuit impedance?

  1. 25 Ω Correct answer.
  2. 65 Ω
  3. 105 Ω
  4. 0 Ω

Explanation

At resonance the inductive and capacitive reactances are equal and opposite, so they cancel and the impedance is simply the resistance, 25 Ω.

Question 42Electrical Calculations and Theory

Each phase of a balanced delta-connected load carries 10 amperes. What is the current in each line conductor?

  1. 17.3 A Correct answer.
  2. 30 A
  3. 10 A
  4. 5 A

Explanation

In a delta connection the line current is √3 times the phase current, so 10 × 1.732 ≈ 17.3 A.

Question 43Electrical Calculations and Theory

A facility has a 100 kW load operating at 0.8 power factor lagging. How much capacitor bank capacity is needed to raise the power factor to 0.95 lagging?

  1. 33 kVAR
  2. 75 kVAR
  3. 42 kVAR Correct answer.
  4. 25 kVAR

Explanation

Original reactive power is 100 × tan(cos⁻¹ 0.8) = 75 kVAR, and the target is 100 × tan(cos⁻¹ 0.95) ≈ 33 kVAR. The capacitor must supply the difference, about 42 kVAR.

Question 44Electrical Calculations and Theory

A 30-ohm resistor is connected in parallel with a capacitor having 40 ohms of capacitive reactance. What is the magnitude of the total impedance?

  1. 35 Ω
  2. 12 Ω
  3. 24 Ω Correct answer.
  4. 70 Ω

Explanation

For resistance in parallel with pure reactance, Z = (R × XC)/√(R² + XC²) = (30 × 40)/50 = 24 Ω.

Question 45Wiring Methods and Materials

Type NM cable must be secured and supported at intervals not exceeding which distance?

  1. 10 ft
  2. 3 ft
  3. 4-1/2 ft Correct answer.
  4. 6 ft

Explanation

Nonmetallic-sheathed cable must be secured and supported at intervals not exceeding 1.4 m (4 1/2 ft) and within 300 mm (12 in) of every box or fitting. This interval is specific to the cable type and differs from raceway support rules.

Question 46Wiring Methods and Materials

Type NM cable must be secured within what distance of each box or enclosure?

  1. 8 in
  2. 6 in
  3. 12 in Correct answer.
  4. 18 in

Explanation

The cable must be fastened within 300 mm (12 in) of each box, cabinet, or fitting so that movement and strain at terminations are limited. Securement is in addition to the 4 1/2 ft support interval.

Question 47Wiring Methods and Materials

What is the maximum permitted support interval for electrical metallic tubing (EMT)?

  1. 10 ft Correct answer.
  2. 12 ft
  3. 8 ft
  4. 6 ft

Explanation

EMT must be supported at intervals not exceeding 3 m (10 ft) and within 900 mm (3 ft) of boxes and fittings. The 10 ft figure applies to the span between supports, not to the distance from a box.

Question 48Wiring Methods and Materials

A grounded (neutral) conductor must be identified by which insulation color?

  1. Green with yellow stripes
  2. White or gray Correct answer.
  3. Bare copper
  4. Black or red

Explanation

Grounded conductors are identified by white or gray insulation or marking at terminations. This color identification keeps the neutral distinguishable from equipment grounding and ungrounded conductors throughout the system.

Question 49Wiring Methods and Materials

Cut ends of electrical metallic tubing must be ___ before conductors are installed.

  1. reamed to remove rough edges Correct answer.
  2. flared to a bell shape
  3. threaded with a die
  4. painted with a corrosion inhibitor

Explanation

EMT cut ends must be reamed to remove burrs and sharp edges that could abrade conductor insulation during pulling. Reaming is required in addition to any corrosion protection applied to the cut.

Question 50Wiring Methods and Materials

Type NM cable is permitted in which of the following locations?

  1. In a raceway outdoors exposed to rain
  2. Buried directly in the ground
  3. Inside a dry, protected wall cavity Correct answer.
  4. Inside a wet location such as a car wash

Explanation

Nonmetallic-sheathed cable is a dry-location wiring method used in concealed or protected dry areas. It is not listed for direct burial or for wet locations.