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ONTARIO ELECTRICIAN
LICENSING EXAM PRACTICE TEST
(2025) – 200 QUESTIONS WITH
ANSWERS & EXPLANATIONS
Ontario Electrician Licensing Exam – Practice Test (1–50)
1. What is the main purpose of the electrical grounding system? A. Increase voltage B. Provide a safe path for fault current C. Reduce wire size D. Increase current flow Grounding provides a safe path to earth for fault current, preventing electric shock and equipment damage. **Answer: B
- According to the Canadian Electrical Code, what colour is typically used for grounding conductors?** A. Red B. White C. Green or bare D. Blue Ground conductors are usually green insulation or bare copper. **Answer: C
- What device protects circuits from overloads and short circuits?**
A. Transformer B. Circuit breaker C. Capacitor D. Relay Circuit breakers automatically open a circuit when excessive current flows. Answer: B
4. What does voltage measure? A. Electrical pressure B. Current flow C. Resistance D. Power consumption Voltage is the electrical potential difference that drives current. **Answer: A
- What is the unit of electrical current?** A. Volt B. Ohm C. Ampere D. Watt Current is measured in amperes (amps). **Answer: C
- What is the formula for Ohm’s Law?** A. V = I × R B. P = V × I C. R = P ÷ I D. I = V × P Ohm’s Law states voltage equals current multiplied by resistance. Answer: A
11. What is the unit of electrical power? A. Volt B. Ampere C. Watt D. Ohm Electrical power is measured in watts. **Answer: C
- What does a transformer do?** A. Changes voltage levels B. Stores electricity C. Generates electricity D. Measures voltage Transformers step voltage up or down. **Answer: A
- What is the typical voltage of a standard residential outlet in Ontario?** A. 120 V B. 240 V C. 480 V D. 600 V Standard outlets provide approximately 120 volts. **Answer: A
- What safety device detects ground faults in circuits?** A. AFCI B. GFCI C. Fuse D. Relay GFCI devices shut off power when ground faults occur.
Answer: B
15. What type of wire insulation is commonly used in residential wiring? A. Rubber only B. Thermoplastic (PVC) C. Paper D. Glass PVC insulation is commonly used in modern wiring. **Answer: B
- What does a disconnect switch do?** A. Measures current B. Isolates electrical equipment from power C. Increases voltage D. Stores electricity Disconnect switches allow safe servicing. **Answer: B
- What happens during a short circuit?** A. Current decreases B. Current bypasses resistance and increases rapidly C. Voltage disappears D. Resistance increases Short circuits create excessive current flow. **Answer: B
- What tool is used to measure electrical resistance?** A. Voltmeter B. Ohmmeter C. Ammeter D. Clamp meter
C. Resistance only D. Current supply Loads use electrical energy. Answer: B
23. What is the purpose of bonding? A. Increase voltage B. Ensure electrical continuity and safety C. Reduce insulation D. Store electricity Bonding connects conductive parts to prevent shock. **Answer: B
- What does AFCI stand for?** A. Arc Fault Circuit Interrupter B. Automatic Fuse Circuit Indicator C. Alternating Fault Current Input D. Arc Flow Control Interface AFCI devices detect dangerous arc faults. **Answer: A
- What does a clamp meter measure?** A. Current without breaking the circuit B. Voltage only C. Resistance only D. Frequency only Clamp meters measure current around a conductor. **Answer: A
- What type of circuit has only one path for current?**
A. Parallel circuit B. Series circuit C. Combination circuit D. Open circuit Series circuits have a single current path. Answer: B
27. What type of circuit provides multiple current paths? A. Series B. Parallel C. Open D. Closed Parallel circuits supply multiple paths. **Answer: B
- What is electrical frequency measured in?** A. Hertz B. Watts C. Ohms D. Amperes Frequency measures cycles per second. **Answer: A
- What is the typical power frequency in Canada?** A. 50 Hz B. 60 Hz C. 120 Hz D. 240 Hz Canada uses 60 Hz AC power. Answer: B
Underground wiring requires cables designed to resist moisture and soil conditions. Answer: C
34. What is voltage drop in a circuit? A. Increase in voltage B. Loss of voltage as electricity travels through conductors C. Increase in current D. Total voltage output Voltage drop occurs due to resistance in conductors over distance. **Answer: B
- What is the primary function of insulation on electrical conductors?** A. Increase voltage B. Prevent electrical leakage and shock C. Increase current D. Reduce resistance Insulation protects users and prevents unintended current flow. **Answer: B
- Which device protects circuits from arc faults in residential systems?** A. GFCI B. AFCI C. Fuse D. Transformer Arc Fault Circuit Interrupters detect dangerous arc conditions that could cause fires. **Answer: B
- What is the purpose of lockout/tagout procedures?**
A. Increase voltage B. Prevent accidental energizing of equipment during maintenance C. Improve circuit efficiency D. Increase current flow Lockout/tagout ensures equipment cannot be turned on while being serviced. Answer: B
38. What device measures electrical power directly? A. Voltmeter B. Wattmeter C. Ohmmeter D. Ammeter Wattmeters measure electrical power in watts. **Answer: B
- What is electrical impedance?** A. Resistance in AC circuits including reactance B. Voltage only C. Current only D. Magnetic energy Impedance includes resistance and reactance affecting AC current. **Answer: A
- What is the function of a contactor?** A. Store energy B. Electrically control power circuits C. Increase voltage D. Measure resistance Contactors switch high-power circuits using low-power control signals. Answer: B
45. What is a three-phase electrical system commonly used for? A. Small household appliances B. Industrial equipment and large motors C. Battery charging only D. Lighting circuits only Three-phase systems provide efficient power for heavy loads. **Answer: B
- What is the purpose of a surge protector?** A. Increase voltage B. Protect equipment from voltage spikes C. Increase current D. Reduce frequency Surge protectors guard against transient voltage spikes. **Answer: B
- What is electrical continuity?** A. Break in circuit B. Uninterrupted electrical path C. Increase in resistance D. Voltage loss Continuity indicates that current can flow through the circuit. **Answer: B
- What is insulation resistance testing used for?** A. Measuring voltage B. Checking insulation integrity in wiring C. Measuring current D. Testing power output Insulation tests ensure wiring insulation has not degraded.
Answer: B
49. What is a grounding electrode? A. Circuit breaker B. Conductor connected to earth grounding system C. Transformer D. Capacitor Grounding electrodes connect electrical systems to earth. **Answer: B
- What is a service entrance?** A. The point where electrical power enters a building B. Circuit breaker C. Generator D. Transformer Service entrances connect utility supply to building wiring. **Answer: A
- What does a diode allow in an electrical circuit?** A. Current flow in both directions B. Current flow in one direction only C. Voltage increase D. Resistance increase Diodes act as one-way valves for electrical current. **Answer: B
- What device converts AC to DC power?** A. Transformer B. Rectifier C. Capacitor D. Relay
A. Decoration B. Identify circuits and improve safety C. Increase voltage D. Reduce resistance Proper labeling helps identify circuits during maintenance. Answer: B
57. What is the primary function of a motor starter? A. Start and protect motors from overload B. Increase motor voltage C. Store electricity D. Convert current Motor starters control motor operation and provide protection. **Answer: A
- What type of conductor material is most commonly used in building wiring?** A. Steel B. Copper C. Aluminum foil D. Lead Copper is widely used due to its excellent conductivity. **Answer: B
- What does wattage represent?** A. Electrical resistance B. Electrical power consumption C. Electrical pressure D. Electrical frequency Watts measure the rate of electrical energy use. Answer: B
60. What type of breaker protects against ground faults and overloads? A. Standard breaker B. Combination AFCI/GFCI breaker C. Fuse D. Relay Combination breakers protect against both arc faults and ground faults. **Answer: B
- What is the purpose of a junction box?** A. Increase current B. Protect wire connections C. Generate electricity D. Store voltage Junction boxes enclose and protect wiring connections. **Answer: B
- What tool strips insulation from wires?** A. Pliers B. Wire stripper C. Hammer D. Saw Wire strippers remove insulation without damaging conductors. **Answer: B
- What is a circuit overload?** A. Excess voltage B. Excess current beyond circuit capacity C. Low current D. Balanced current Overloads occur when too many loads draw current from a circuit.
Ballasts control current in fluorescent lighting systems. Answer: B
68. What does a power factor represent? A. Voltage efficiency B. Efficiency of electrical power usage C. Frequency level D. Resistance value Power factor measures how effectively electrical power is used. **Answer: B
- What safety equipment protects electricians from electric shock?** A. Rubber insulating gloves B. Steel gloves C. Cotton gloves D. Plastic gloves Insulated gloves prevent electrical contact. **Answer: A
- What is the purpose of conduit bending?** A. Increase voltage B. Route conduit around obstacles C. Store electricity D. Reduce resistance Conduit bending allows proper installation around structures. **Answer: B
- What is the typical voltage of a large appliance circuit in homes?**
A. 120 V
B. 240 V
C. 60 V
D. 480 V
Large appliances like dryers use 240 volts. Answer: B
72. What is a load calculation used for? A. Determining electrical demand of a building B. Measuring resistance C. Measuring frequency D. Testing insulation Load calculations ensure systems can handle electrical demand. **Answer: A
- What does a disconnecting means allow?** A. Increase voltage B. Safely isolate electrical equipment C. Store electricity D. Increase current Disconnect switches allow equipment servicing. **Answer: B
- What is a busbar?** A. Insulated wire B. Conductive strip distributing power in panels C. Generator D. Transformer Busbars distribute electricity inside electrical panels. Answer: B
