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Red Seal Industrial Electrician practice questions

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Question 1Occupational Health and Safety, Codes and Standards

When a worker is going to service electrical equipment that has been de-energized, who must apply a lock to the isolating device?

  1. The plant electrician on shift
  2. The crew supervisor for the area
  3. The maintenance planner for the job
  4. Each worker who is exposed Correct answer.

Explanation

Each worker who will be exposed to the hazard applies a personal lock so the energy source cannot be re-energized without that worker's knowledge and consent. Group lockout arrangements still require every exposed worker to have individual control.

Question 2Occupational Health and Safety, Codes and Standards

According to the Canadian Electrical Code, receptacles installed within what distance of a sink must be protected by a ground fault circuit interrupter?

  1. 2.5 m
  2. 3.0 m
  3. 1.5 m Correct answer.
  4. 0.5 m

Explanation

The CE Code requires GFCI protection for receptacles within 1.5 m of a sink, bathtub or shower. The wet environment and nearby grounded surfaces increase the risk of a fatal shock.

Question 3Occupational Health and Safety, Codes and Standards

For electrical equipment operating at 750 V or less, what minimum working space does the CE Code require in front of the equipment?

  1. 1.5 m
  2. 1.0 m Correct answer.
  3. 0.5 m
  4. 0.75 m

Explanation

Rule 2-308 sets a minimum clear working space of 1 m in front of electrical equipment rated 750 V or less. The space must be clear of storage and arranged so live parts can be worked on safely.

Question 4Occupational Health and Safety, Codes and Standards

Under WHMIS, which document must be readily available to workers for each hazardous product in the workplace?

  1. The purchase order
  2. The manufacturer's invoice
  3. The equipment log book
  4. The safety data sheet Correct answer.

Explanation

WHMIS requires the supplier to provide a safety data sheet and the employer to keep it readily accessible to workers. The sheet uses a standardized 16-section format covering hazards, handling and emergency measures.

Question 5Occupational Health and Safety, Codes and Standards

A conductor with green insulation, or green with a yellow stripe, is used in a Canadian installation as

  1. a phase conductor
  2. a neutral conductor
  3. a bonding conductor Correct answer.
  4. a control conductor

Explanation

The CE Code reserves green, and green with yellow stripes, for bonding conductors. Neutral conductors are identified by white or natural grey, and phase conductors use other colours.

Question 6Occupational Health and Safety, Codes and Standards

Under CE Code definitions, circuits operating at more than 750 V are classified as

  1. low voltage
  2. high voltage Correct answer.
  3. medium voltage
  4. extra-low voltage

Explanation

The CE Code defines high voltage as any potential above 750 V. Low voltage covers 31 V to 750 V, and extra-low voltage is 30 V or less.

Question 7Occupational Health and Safety, Codes and Standards

Before a worker enters a confined space that may contain a hazardous atmosphere, the employer must ensure that

  1. the space is flushed with oxygen
  2. a co-worker stands at the entrance
  3. the entry is completed within a 15 minute window
  4. the atmosphere is tested and recorded Correct answer.

Explanation

Atmospheric testing for oxygen, flammables and toxic contaminants must be done before entry and the results recorded. Entry is permitted only when the results show the space is safe or suitable controls are in place.

Question 8Occupational Health and Safety, Codes and Standards

The arc flash boundary marked on electrical equipment is the distance at which

  1. equipment fault current is fully interrupted
  2. incident energy equals 1.2 cal/cm² Correct answer.
  3. the sound level exceeds 85 dBA
  4. the shock hazard reaches 50 V

Explanation

The arc flash boundary is defined as the distance at which incident energy falls to 1.2 cal/cm², roughly the onset of a second-degree burn. Inside that boundary, arc-rated protection is required.

Question 9Occupational Health and Safety, Codes and Standards

A multimeter used to measure voltage on a 600 V panelboard feeder should carry which minimum IEC measurement category rating?

  1. CAT II
  2. No rating is required
  3. CAT III Correct answer.
  4. CAT I

Explanation

CAT III covers measurements at distribution-level fixed installations such as panelboards and feeders. CAT II is for portable appliances and CAT I for low-energy electronic circuits.

Question 10Occupational Health and Safety, Codes and Standards

A hazardous location classified as Class II, Division 1 contains

  1. volatile liquids in closed containers
  2. combustible dust in suspension Correct answer.
  3. flammable gases that are continuously present
  4. ignitable fibres processed routinely

Explanation

Class II locations are those made hazardous by combustible dust, and Division 1 covers conditions where dust is present in the air during normal operations. Gases and vapours fall under Class I.

Question 11Occupational Health and Safety, Codes and Standards

Under Canadian OHS requirements, work on energized electrical equipment is permitted only when

  1. the equipment is rated above 750 V
  2. the worker holds a journeyperson certificate
  3. a second qualified worker is present
  4. de-energizing would create a greater hazard Correct answer.

Explanation

Energized work is restricted to cases where de-energizing would introduce a greater hazard or is not practicable, supported by a hazard assessment and a work permit. Qualification and standby personnel are supporting controls, not the authorizing condition.

Question 12Occupational Health and Safety, Codes and Standards

After a disconnect has been opened and locked, the required next step before work begins is to

  1. notify the utility before beginning work
  2. apply temporary protective grounds at the panel
  3. test for absence of voltage Correct answer.
  4. remove the fuses and keep them on hand

Explanation

Isolation must be verified with a tester rated for the circuit voltage, and where possible the equipment should be tried to confirm it will not start. Only then may work proceed.

Question 13Occupational Health and Safety, Codes and Standards

When both an ambient temperature correction and a conductor fill adjustment apply to a conductor, its ampacity is determined by

  1. averaging the two factors and rounding up
  2. applying only the more severe of the two
  3. applying the ambient correction factor only
  4. multiplying both factors together Correct answer.

Explanation

The table ampacity is multiplied by the temperature correction factor and by the bundling adjustment factor. The final usable ampacity is also limited by the termination temperature rating.

Question 14Occupational Health and Safety, Codes and Standards

Ventilation of a lead-acid battery room is provided mainly to prevent the accumulation of

  1. nitrogen
  2. carbon monoxide
  3. sulfur dioxide
  4. hydrogen gas Correct answer.

Explanation

Charging lead-acid cells releases hydrogen, which forms an explosive mixture with air at low concentrations. Ventilation keeps the concentration well below the explosive limit.

Question 15Occupational Health and Safety, Codes and Standards

Receptacles supplied by temporary wiring on a construction site must be

  1. protected by a GFCI Correct answer.
  2. connected to a standby generator
  3. installed at least 1.8 m above grade
  4. enclosed in rigid metal conduit throughout

Explanation

Section 76 requires ground fault circuit interrupter protection for receptacles fed by temporary wiring on construction sites, because of damp conditions and frequent cord damage.

Question 16Occupational Health and Safety, Codes and Standards

The CE Code recommends that voltage drop on a branch circuit not exceed

  1. 1%
  2. 2%
  3. 3% Correct answer.
  4. 5%

Explanation

Voltage drop on a branch circuit should not exceed 3%, with a combined feeder plus branch drop of 5%. Excessive drop causes poor equipment performance and overheating.

Question 17Occupational Health and Safety, Codes and Standards

Immediately before use, rubber insulating gloves must be

  1. labelled with the worker's name
  2. washed with a solvent
  3. air-tested and visually inspected Correct answer.
  4. stored inside out

Explanation

Each pair must be inspected for cuts, punctures and contamination and air-tested for leaks before every use. Periodic dielectric retesting is also required per the manufacturer's interval.

Question 18Occupational Health and Safety, Codes and Standards

Bonding the normally non-current-carrying metal parts of equipment is intended to

  1. balance the load between the phases
  2. provide a low-impedance fault path Correct answer.
  3. prevent nuisance tripping of breakers
  4. reduce the voltage drop on the circuit

Explanation

Bonding creates a low-impedance path back to the source so that fault current is high enough to operate the overcurrent device quickly. It also keeps metal parts at or near earth potential during a fault.

Question 19Occupational Health and Safety, Codes and Standards

In a Class I hazardous location, sealing fittings are installed in conduit systems to

  1. prevent gases from passing through the conduit Correct answer.
  2. support the conduit against vibration
  3. provide a grounding connection at the boundary
  4. drain condensate from the conduit system

Explanation

Seals block the passage of flammable gases or vapours through the raceway so they cannot reach an unclassified area or an enclosure not rated for the hazard. They are placed near the boundary of the classified area.

Question 20Occupational Health and Safety, Codes and Standards

A worker is found in contact with a live conductor and is unresponsive. The first action of a rescuer is to

  1. throw water on the conductor to cool it
  2. grasp the worker and pull them clear
  3. isolate the supply before touching the worker Correct answer.
  4. begin cardiopulmonary resuscitation at once

Explanation

Touching a casualty still in contact with an energized conductor makes the rescuer a second victim. The supply must be de-energized, or the casualty moved with a rated insulated device, before rescue breathing or CPR begins.

Question 21Occupational Health and Safety, Codes and Standards

If the distance from an arcing fault is doubled, the incident energy at the new location approximately

  1. decreases to about one quarter Correct answer.
  2. remains about the same
  3. increases by a factor of two
  4. decreases to about one half

Explanation

Incident energy falls roughly with the square of the distance from the arc, so doubling the distance cuts the energy to about 25%. This is why boundary distances and working distances matter so much in arc flash assessments.

Question 22Occupational Health and Safety, Codes and Standards

In the Zone system for Class I hazardous locations, an area where ignitable concentrations of gas are present continuously or for long periods is classified as

  1. Zone 0 Correct answer.
  2. Zone 1
  3. Zone 2
  4. Zone 20

Explanation

Zone 0 covers continuous or long-duration gas presence, Zone 1 covers likely presence during normal operation, and Zone 2 covers unlikely or short-duration presence. Zone 20 is a dust classification.

Question 23Occupational Health and Safety, Codes and Standards

Six current-carrying conductors are installed in a single raceway. According to the CE Code bundling table, the allowable ampacity is

  1. reduced to 80% Correct answer.
  2. reduced to 70%
  3. increased by 80%
  4. left unchanged

Explanation

The bundling adjustment factor for four to six current-carrying conductors is 0.80, so the table ampacity must be reduced to 80%. Higher conductor counts require progressively lower factors.

Question 24Occupational Health and Safety, Codes and Standards

Step potential during a ground fault at an electrical installation is the voltage difference

  1. across the insulation of the equipment
  2. between two points on the earth's surface Correct answer.
  3. between two phases of the supply
  4. between the faulted conductor and earth

Explanation

Step potential is the voltage between two points on the earth a stride apart, caused by fault current spreading through the soil. Touch potential, by contrast, is the voltage between an energized structure and the earth under a person's feet.

Question 25Electrical Theory and Circuit Analysis

A 12 V source is connected across a 4 Ω resistor. What current flows through the resistor?

  1. 16 A
  2. 48 A
  3. 3 A Correct answer.
  4. 0.33 A

Explanation

Ohm's law states that current equals voltage divided by resistance, so I = 12 V ÷ 4 Ω = 3 A. Resistance limits current in direct proportion to its value.

Question 26Electrical Theory and Circuit Analysis

Resistors of 10 Ω, 20 Ω and 30 Ω are connected in series across a 120 V supply. What is the circuit current?

  1. 12 A
  2. 6 A
  3. 2 A Correct answer.
  4. 0.5 A

Explanation

In a series circuit the resistances add, giving 60 Ω total, and current is the same everywhere. Applying Ohm's law gives I = 120 V ÷ 60 Ω = 2 A.

Question 27Electrical Theory and Circuit Analysis

A resistive heater connected to 240 V draws 10 A. What power does the heater dissipate?

  1. 2 400 W Correct answer.
  2. 24 W
  3. 24 000 W
  4. 240 W

Explanation

DC power in a resistive load equals voltage multiplied by current, P = V × I. Here P = 240 V × 10 A = 2 400 W.

Question 28Electrical Theory and Circuit Analysis

A sinusoidal AC voltage has a peak value of 170 V. What is its RMS value?

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

Explanation

For a sine wave, RMS value equals peak value divided by √2. Dividing 170 V by 1.414 gives approximately 120 V, which is the value a voltmeter would display.

Question 29Electrical Theory and Circuit Analysis

What is the period of a 60 Hz sinusoidal waveform?

  1. 1.67 ms
  2. 6 ms
  3. 60 ms
  4. 16.7 ms Correct answer.

Explanation

Period is the reciprocal of frequency, T = 1/f. One cycle at 60 Hz lasts 1 ÷ 60 = 0.01667 s, or about 16.7 ms.

Question 30Electrical Theory and Circuit Analysis

Three resistors are in series across a 120 V supply. The voltage drops across two of them are 45 V and 30 V. What is the voltage drop across the third resistor?

  1. 150 V
  2. 45 V Correct answer.
  3. 75 V
  4. 30 V

Explanation

Kirchhoff's voltage law states that the sum of the voltage drops around a closed loop equals the applied voltage. The third drop is therefore 120 V − 45 V − 30 V = 45 V.

Question 31Electrical Theory and Circuit Analysis

A 6 Ω resistor and a 3 Ω resistor are connected in parallel. What is the equivalent resistance of the combination?

  1. 9 Ω
  2. 1.5 Ω
  3. 2 Ω Correct answer.
  4. 4.5 Ω

Explanation

For two resistors in parallel, the reciprocals add: 1/R = 1/6 + 1/3 = 1/2, so R = 2 Ω. The equivalent resistance of a parallel network is always less than the smallest branch resistance.

Question 32Electrical Theory and Circuit Analysis

At a circuit node, 5 A and 2 A enter and 4 A leaves through one branch. What current leaves through the remaining branch?

  1. 3 A Correct answer.
  2. 7 A
  3. 1 A
  4. 11 A

Explanation

Kirchhoff's current law requires total current entering a node to equal total current leaving. Entering current is 7 A and 4 A already leaves, so the remaining branch carries 3 A.

Question 33Electrical Theory and Circuit Analysis

What is the capacitive reactance of a 26.5 µF capacitor connected to a 60 Hz supply?

  1. 26.5 Ω
  2. 60 Ω
  3. 377 Ω
  4. 100 Ω Correct answer.

Explanation

Capacitive reactance is given by XC = 1/(2πfC). With f = 60 Hz and C = 26.5 µF, XC = 1/(2π × 60 × 26.5 × 10⁻⁶) ≈ 100 Ω.

Question 34Electrical Theory and Circuit Analysis

A 0.1 H inductor is connected to a 50 Hz supply. What is its inductive reactance?

  1. 31.4 Ω Correct answer.
  2. 0.63 Ω
  3. 3.14 Ω
  4. 314 Ω

Explanation

Inductive reactance is given by XL = 2πfL. Substituting f = 50 Hz and L = 0.1 H gives XL = 2π × 50 × 0.1 ≈ 31.4 Ω.

Question 35Electrical Theory and Circuit Analysis

A single-phase load draws 10 A at 240 V with a power factor of 0.8. What real power does the load consume?

  1. 1 200 W
  2. 3 000 W
  3. 2 400 W
  4. 1 920 W Correct answer.

Explanation

Real power equals apparent power multiplied by the power factor: P = V × I × cos θ. Here 240 V × 10 A = 2 400 VA, and 2 400 × 0.8 = 1 920 W.

Question 36Electrical Theory and Circuit Analysis

A balanced three-phase load operates at 480 V line voltage and 20 A line current with a power factor of 1.0. What is the total real power?

  1. 28.8 kW
  2. 9.6 kW
  3. 48 kW
  4. 16.6 kW Correct answer.

Explanation

Total real power in a balanced three-phase circuit is P = √3 × VL × IL × cos θ. Substituting gives 1.732 × 480 × 20 × 1.0 ≈ 16.6 kW.

Question 37Electrical Theory and Circuit Analysis

A 12 V supply is applied to a series combination of 4 kΩ and 8 kΩ. What voltage appears across the 8 kΩ resistor?

  1. 12 V
  2. 8 V Correct answer.
  3. 6 V
  4. 4 V

Explanation

In a series divider the voltage divides in proportion to resistance. The 8 kΩ resistor takes 8/12 of the 12 V supply, which is 8 V.

Question 38Electrical Theory and Circuit Analysis

A 100 µF capacitor is charged through a 10 kΩ resistor. What is the time constant of the circuit?

  1. 10 s
  2. 1 s Correct answer.
  3. 0.1 s
  4. 100 s

Explanation

The RC time constant is the product of resistance and capacitance: τ = R × C. Using 10 000 Ω × 100 × 10⁻⁶ F gives a time constant of 1 s.

Question 39Electrical Theory and Circuit Analysis

An ideal transformer has 1200 turns on the primary and 100 turns on the secondary. If the primary is supplied at 240 V, what is the secondary voltage?

  1. 200 V
  2. 2 V
  3. 24 V
  4. 20 V Correct answer.

Explanation

Secondary voltage relates to primary voltage by the turns ratio: VS = VP × (NS/NP). With a ratio of 100/1200, the secondary voltage is 240 × 0.0833 ≈ 20 V.

Question 40Electrical Theory and Circuit Analysis

A resistor of 30 Ω is in series with a capacitor having a reactance of 40 Ω. What is the magnitude of the total impedance?

  1. 10 Ω
  2. 70 Ω
  3. 50 Ω Correct answer.
  4. 1 200 Ω

Explanation

Resistance and capacitive reactance are 90° out of phase, so they add vectorially: Z = √(R² + XC²). Thus Z = √(30² + 40²) = √2500 = 50 Ω.

Question 41Electrical Theory and Circuit Analysis

A series circuit contains 6 Ω of resistance, 12 Ω of inductive reactance and 4 Ω of capacitive reactance. What is the total impedance?

  1. 10 Ω Correct answer.
  2. 22 Ω
  3. 14 Ω
  4. 8 Ω

Explanation

Net reactance is XL − XC = 12 Ω − 4 Ω = 8 Ω, and impedance is Z = √(R² + Xnet²). Therefore Z = √(6² + 8²) = √100 = 10 Ω.

Question 42Electrical Theory and Circuit Analysis

A series RLC circuit has an inductance of 0.1 H and a capacitance of 100 µF. At approximately what frequency will the circuit be resonant?

  1. 50 Hz Correct answer.
  2. 5 Hz
  3. 159 Hz
  4. 500 Hz

Explanation

Resonance occurs where XL equals XC, giving fr = 1/(2π√(LC)). With LC = 1 × 10⁻⁵, √(LC) = 3.16 × 10⁻³, so fr ≈ 50 Hz.

Question 43Electrical Theory and Circuit Analysis

A 24 V source feeds a 12 Ω resistor in series with a 24 Ω resistor, with the output taken across the 24 Ω resistor. What are the Thevenin voltage and Thevenin resistance seen at that output?

  1. 8 V in series with 8 Ω
  2. 16 V in series with 36 Ω
  3. 16 V in series with 24 Ω
  4. 16 V in series with 8 Ω Correct answer.

Explanation

The Thevenin voltage is the open-circuit output voltage, 24 × 24/36 = 16 V. The Thevenin resistance is found by replacing the source with a short, leaving 12 Ω in parallel with 24 Ω, which equals 8 Ω.

Question 44Electrical Theory and Circuit Analysis

A copper conductor has a resistance of 10 Ω at 20 °C. Using a temperature coefficient of 0.00393 per °C at 20 °C, what is its resistance at 70 °C?

  1. 11.0 Ω
  2. 10.2 Ω
  3. 20 Ω
  4. 12 Ω Correct answer.

Explanation

Resistance rises with temperature according to R = R₂₀[1 + α(T − 20)]. The 50 °C rise multiplies the resistance by 1 + 0.00393 × 50 = 1.1965, giving about 12 Ω.

Question 45Wiring, Cabling, Raceways and Enclosures

What is the maximum percentage of a raceway's internal cross-sectional area that may be occupied by three or more conductors?

  1. 60 percent
  2. 53 percent
  3. 31 percent
  4. 40 percent Correct answer.

Explanation

For a raceway containing three or more conductors, the total conductor area may not exceed 40 percent of the raceway's internal cross-sectional area. The lower limits exist so that conductors can be pulled without damage and without overheating.

Question 46Wiring, Cabling, Raceways and Enclosures

What is the maximum spacing between supports for a straight horizontal run of 21 mm electrical metallic tubing?

  1. 4.5 m
  2. 1.0 m
  3. 3.0 m Correct answer.
  4. 1.5 m

Explanation

Electrical metallic tubing must be supported at intervals not exceeding 3.0 m and within 1.0 m of every box, fitting, or termination. The support keeps the tubing from sagging and separating at couplings.

Question 47Wiring, Cabling, Raceways and Enclosures

Which colour identifies the grounded conductor of a branch circuit in a typical building installation?

  1. Black
  2. Red
  3. White or natural grey Correct answer.
  4. Green

Explanation

The grounded (neutral) conductor must be identified by a white or natural grey finish for its entire length. This identification lets anyone working on the circuit distinguish the grounded conductor from ungrounded conductors.

Question 48Wiring, Cabling, Raceways and Enclosures

Between two outlet boxes, what is the maximum total amount of bending permitted in a run of rigid conduit?

  1. 360 degrees Correct answer.
  2. 180 degrees
  3. 90 degrees
  4. 270 degrees

Explanation

A raceway run between boxes, fittings, or enclosures may contain no more than the equivalent of four 90-degree bends, for a total of 360 degrees. Beyond that, conductors cannot be pulled in without damage.

Question 49Wiring, Cabling, Raceways and Enclosures

A conductor with green insulation is installed in a raceway to serve which function?

  1. Bonding Correct answer.
  2. Ungrounded conductor
  3. Switched conductor
  4. Neutral

Explanation

Green insulation, or green with a yellow stripe, identifies a bonding conductor. It is used to connect non-current-carrying metal parts so they remain at the same potential as the system grounding point.

Question 50Wiring, Cabling, Raceways and Enclosures

A raceway passes through a wall that is a fire separation. What must be done at the penetration?

  1. Nothing extra if the raceway is steel
  2. Seal the opening with a listed firestop assembly Correct answer.
  3. Install an expansion fitting at the wall
  4. Fill the raceway with sealing compound for its full length

Explanation

Any opening made through a fire separation must be closed with a listed firestop assembly so the assembly's fire-resistance rating is maintained. The firestop must be appropriate for the type of penetrating item and the construction of the wall.