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Question 1 Which of the following is the primary purpose of a grounding electrode system in a residential installation? A) To provide a low-impedance path for fault current B) To reduce voltage drop in branch circuits C) To increase the ampacity of conductors D) To serve as a neutral conductor Answer: A Explanation: The grounding electrode provides a low-impedance path to earth so that fault currents can be safely cleared by protective devices. Question 2 In the Canadian Electrical Code, what is the maximum allowable voltage drop for a feeder supplying a continuous load when the feeder length is 100 m? A) 2 % B) 3 % C) 4 % D) 5 % Answer: B Explanation: The CEC permits a maximum of 3 % voltage drop for feeders supplying continuous loads to maintain efficient operation. Question 3 Which type of conduit is permitted for outdoor installations where it may be exposed to direct sunlight? A) Rigid metal conduit (RMC) only B) PVC conduit without UV stabilizer C) EMT with a UV-resistant coating D) Rigid nonmetallic conduit (RNC) with UV protection Answer: D Explanation: RNC (often called PVC conduit) must be rated for UV exposure when used outdoors; otherwise it degrades. Question 4 A 3-phase, 4-wire wye-connected system has a line-to-line voltage of 480 V. What is the line-to-neutral voltage? A) 277 V
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B) 240 V
C) 414 V
D) 480 V
Answer: A Explanation: In a wye system, V_L-N = V_L-L ÷ √3, so 480 ÷ 1.732 ≈ 277 V. Question 5 Which of the following devices is required to protect a 15 A, 120 V receptacle circuit in a dwelling unit? A) A 20 A GFCI breaker B) A 15 A standard circuit breaker C) A 15 A GFCI breaker or receptacle D) A 20 A standard breaker with a GFCI outlet downstream Answer: C Explanation: The CEC requires either a 15 A GFCI breaker at the panel or a GFCI receptacle on the circuit. Question 6 The ampacity of a 12 AWG copper conductor with 90 °C insulation in a raceway is 30 A according to Table 2 of the CEC. If the conductor is bundled with three other conductors of the same size, what derating factor should be applied? A) 0. B) 0. C) 0. D) 0. Answer: B Explanation: For four current-carrying conductors, the CEC requires a derating factor of 0.80; however, because the conductors are 12 AWG with 90 °C rating, the next step is to apply the 0.80 factor, yielding 24 A, which is below the required 30 A, so a larger conductor would be needed. Question 7 Which of the following is the correct method to calculate conduit fill for a raceway containing six #10 THHN conductors? A) Use the 40 % fill rule for more than three conductors B) Use the 31 % fill rule for more than three conductors
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Explanation: The CEC requires the neutral to be bonded to the grounding electrode at the service equipment (the point of first disconnect). Question 11 What is the minimum size of a grounding conductor for a 100 A feeder using 2 AWG copper THHN? A) 10 AWG copper B) 8 AWG copper C) 6 AWG copper D) 4 AWG copper Answer: B Explanation: Table 250-122 of the CEC specifies a minimum grounding conductor size of 8 AWG copper for a 100 A feeder. Question 12 Which of the following is the correct definition of “continuous load” according to the CEC? A) A load that operates for more than 3 hours continuously in a 24-hour period B) A load that operates for more than 6 hours continuously in a 24-hour period C) Any load that is not a motor D) Any load that is protected by a GFCI device Answer: B Explanation: The CEC defines a continuous load as one that operates for more than 6 hours consecutively. Question 13 A 4-wire, 120/240 V, 200 A service entrance has a main breaker rated at 200 A. What is the maximum permissible rating for a sub-panel feeder derived from this service? A) 150 A B) 175 A C) 200 A D) 225 A Answer: C Explanation: The feeder may be rated up to the rating of the service entrance main breaker, provided the conductors are sized accordingly.
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Question 14 Which of the following conduit sizes is the minimum required to accommodate three 4/0 AWG aluminum conductors plus a 4 AWG grounding conductor? A) 2 in. EMT B) 2 in. RMC C) 1-1/2 in. EMT D) 1-1/4 in. RMC Answer: B Explanation: Using the 31 % fill rule, only a 2 in. RMC provides enough internal area for the large conductors and grounding conductor. Question 15 The CEC requires that a receptacle installed in a bathroom be GFCI protected. Which of the following configurations also satisfies the code? A) A 20 A GFCI breaker feeding the bathroom circuit B) A 15 A standard breaker with a GFCI receptacle only at the vanity C) A 20 A standard breaker with a GFCI receptacle at the tub only D) Any of the above, as long as the receptacle is within 1.5 m of the tub Answer: A Explanation: A 20 A GFCI breaker protects the entire bathroom circuit, meeting the CEC requirement. Question 16 Which of the following statements about the use of “metallic raceways” for grounding conductors is correct? A) Grounding conductors may be omitted if the raceway is metal. B) Metal raceways provide a grounding path but must still contain a grounding conductor. C) Metal raceways are prohibited in wet locations. D) Grounding conductors are only required in non-metallic raceways. Answer: B Explanation: The CEC requires a dedicated grounding conductor even when a metal raceway is used, because the raceway alone may not guarantee a low-impedance path. Question 17 For a lighting circuit with a total load of 3 kW, what is the minimum size of the branch-circuit breaker required?
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B) 800 A
C) 1600 A
D) 3200 A
Answer: D Explanation: Large copper bus bars have very high ampacity; a 1500 mm² bus typically handles well over 3000 A for a 10 kA fault rating. Question 21 Which of the following is the correct method for sizing a feeder for a 30 kW, 240 V, three-phase motor with a service factor of 1.25? A) Use 125 % of the motor full-load current B) Use 100 % of the motor full-load current C) Use 150 % of the motor full-load current D) Use the motor name-plate current only Answer: A Explanation: The CEC requires feeder conductors to be sized at 125 % of the motor’s full-load current to accommodate starting currents. Question 22 Which of the following is the minimum required clearance between a service drop and a grounded metal water pipe? A) 0 mm (contact allowed) B) 25 mm C) 50 mm D) 100 mm Answer: B Explanation: The CEC mandates a minimum of 25 mm clearance to prevent accidental contact and corrosion. Question 23 A receptacle is installed 0.75 m above the floor in a garage. Which protection is required by the CEC? A) GFCI only B) AFCI only C) Both GFCI and AFCI D) No special protection required
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Answer: A Explanation: Garages are considered damp locations; the CEC requires GFCI protection for receptacles. Question 24 Which of the following statements about “knock-out” fittings in metal conduit is true? A) They must be welded to the conduit for a permanent connection. B) They can be left open if the conduit is later capped. C) They must be secured with a listed connector before the conduit is covered. D) They are optional for conduit runs longer than 5 m. Answer: C Explanation: Knock-out fittings must be closed with a listed connector (e.g., a locknut or compression fitting) to maintain the raceway’s integrity. Question 25 The CEC permits the use of “cable trays” for which of the following applications? A) Direct burial in the ground B) Supporting insulated conductors in a fire-rated assembly C) Carrying high-voltage transmission lines D) Temporary power for construction sites only Answer: B Explanation: Cable trays can be used to support insulated conductors within fire-rated assemblies, provided the tray system is listed for the application. Question 26 A 120 V, 15 A receptacle is to be installed in a kitchen countertop area. Which of the following is the minimum number of dedicated circuits required? A) One 15 A circuit B) One 20 A circuit C) Two 20 A circuits D) Two 15 A circuits Answer: C Explanation: The CEC requires at least two 20 A small-appliance circuits to serve countertop receptacles.
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A) 30 A
B) 40 A
C) 50 A
D) 60 A
Answer: B Explanation: The motor full-load current is (12000 ÷ (√ 3 × 208)) ≈ 33 A. A 40 A breaker provides a suitable 125 % margin. Question 31 Which of the following statements about “THHN” conductors is correct? A) They are suitable for use in wet locations without any additional protection. B) They must be installed in rigid metal conduit only. C) They are rated for 90 °C but limited to 75 °C when terminations are rated 75 °C. D) They cannot be used for grounding conductors. Answer: C Explanation: THHN conductors have a 90 °C rating, but the CEC limits them to 75 °C in most termination points unless the equipment is rated for 90 °C. Question 32 In a multi-wire branch circuit (MWBC) supplying two 120 V circuits, how must the neutral be handled? A) Each circuit must have its own neutral. B) A shared neutral is permitted if the two hots are on opposite phases. C) The neutral must be larger than the hot conductors. D) No neutral is required for an MWBC. Answer: B Explanation: The CEC allows a shared neutral on an MWBC provided the two ungrounded conductors are on opposite phases, ensuring neutral current cancellation. Question 33 Which of the following is the minimum required clearance between a 120 V receptacle and a combustible wall finish? A) 0 mm (direct contact allowed) B) 12 mm
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C) 25 mm D) 38 mm Answer: B Explanation: The CEC specifies a minimum of 12 mm clearance to prevent overheating of combustible finishes. Question 34 A 240 V, 30 A dryer circuit requires a dedicated branch circuit. Which of the following conduit fill calculations is correct for three 6 AWG THHN conductors (two hots and a ground) in 1-in. EMT? A) 28 % fill – acceptable B) 33 % fill – exceeds limit C) 40 % fill – acceptable for three conductors D) 53 % fill – acceptable for any number of conductors Answer: A Explanation: For three conductors, the CEC permits up to 40 % fill. The calculated fill for three 6 AWG THHN in 1-in. EMT is about 28 %, which is within the limit. Question 35 Which of the following devices is required to protect a residential swimming pool pump circuit? A) Standard circuit breaker B) GFCI breaker C) AFCI breaker D) Surge protective device Answer: B Explanation: The CEC requires GFCI protection for pool pump circuits due to the high risk of water-related electric shock. Question 36 When installing a receptacle in a bathroom, what is the required minimum distance from the edge of a bathtub or shower stall? A) 0.6 m B) 0.9 m C) 1.2 m D) 1.5 m Answer: B
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Question 40 Which of the following is the primary reason for installing a “neutral-ground bond” at the service entrance only? A) To reduce electromagnetic interference B) To prevent parallel paths for neutral current C) To increase the ampacity of the neutral conductor D) To allow the use of smaller grounding electrodes Answer: B Explanation: Bonding only at the service entrance prevents parallel neutral-ground paths that could cause circulating currents and safety hazards. Question 41 In a three-phase, 4-wire wye system, which of the following connections is used for a 120 V single-phase load? A) Between any two line conductors B) Between a line conductor and the neutral C) Between any line conductor and ground D) Between the neutral and ground only Answer: B Explanation: A 120 V single-phase load is connected between a line (phase) conductor and the neutral in a wye system. Question 42 Which of the following is the correct minimum height for a receptacle installed in a garage above a workbench? A) 0.45 m above the floor B) 0.60 m above the floor C) 0.75 m above the floor D) 0.90 m above the floor Answer: C Explanation: The CEC specifies a minimum receptacle height of 0.75 m (30 in.) above the floor in a garage work area. Question 43 A 250 kVA transformer has a primary voltage of 13.8 kV and a secondary voltage of 480 V. What is the approximate full-load secondary current? A) 300 A
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B) 350 A
C) 400 A
D) 450 A
Answer: C Explanation: I = kVA ÷ V = 250 000 ÷ 480 ≈ 520 A; however, considering a 0. power factor, the current reduces to about 400 A, which is the standard rating for a 250 kVA 480 V transformer. Question 44 Which of the following is the correct rule for the installation of “flexible metal conduit” (FMC) in a residential dwelling? A) FMC may be used for any interior wiring without support. B) FMC must be supported at intervals not exceeding 3 m. C) FMC is prohibited in any residential application. D) FMC can be used only for grounding conductors. Answer: B Explanation: The CEC requires flexible metal conduit to be supported at intervals not greater than 3 m (10 ft). Question 45 When sizing a feeder for a residential dwelling with a calculated load of 45 kVA at 240 V, what is the minimum ampacity of the feeder conductors? A) 100 A B) 150 A C) 200 A D) 250 A Answer: B Explanation: I = kVA ÷ V = 45 000 ÷ 240 ≈ 187.5 A. Applying a 125 % demand factor for residential loads reduces the required ampacity to approximately 150 A. Question 46 Which of the following devices is required to protect a circuit supplying a fixed electric range in a kitchen? A) 15 A GFCI breaker B) 20 A AFCI breaker C) 30 A standard breaker with a dedicated grounding conductor
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Answer: B Explanation: The CEC mandates at least two 20 A small-appliance circuits for kitchen countertops, regardless of length. Question 50 Which of the following is the correct minimum spacing between a service drop and a window opening in a residential building? A) 0 mm (contact allowed) B) 150 mm C) 300 mm D) 600 mm Answer: C Explanation: The CEC requires a minimum of 300 mm clearance between service drops and window openings to avoid mechanical damage. Question 51 A 120/240 V, 100 A service entrance uses a 4-wire feeder. Which conductor serves as the equipment grounding conductor? A) The neutral conductor B) The ungrounded hot conductor C) A separate green or bare conductor D) The smallest-sized conductor in the raceway Answer: C Explanation: The equipment grounding conductor must be a dedicated green or bare conductor, separate from the neutral. Question 52 Which of the following is the correct method for determining the required size of a grounding electrode conductor for a 400 A service? A) Use the same size as the largest ungrounded conductor. B) Use Table 250-122 to select a minimum of 4 AWG copper. C) Use Table 250-122 to select a minimum of 2 AWG copper. D) Use a 6 AWG aluminum conductor only. Answer: C Explanation: Table 250-122 indicates that a 400 A service requires at least 2 AWG copper for the grounding electrode conductor.
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Question 53 Which of the following is the correct minimum rating for a disconnecting means serving a single-family dwelling? A) 100 A B) 125 A C) 150 A D) 200 A Answer: D Explanation: The CEC requires a minimum main disconnect rating of 200 A for single-family dwellings unless a smaller load calculation justifies a lower rating. Question 54 In a commercial building, a fire alarm system is powered from a dedicated 120 V branch circuit. Which protection is required by the CEC? A) GFCI protection B) AFCI protection C) Surge protective device only D) No special protection required Answer: D Explanation: Fire alarm circuits are not required to have GFCI or AFCI protection under the CEC; they must simply be on a dedicated circuit. Question 55 Which of the following statements about “knob-and-tube” wiring is correct? A) It is allowed for new residential construction. B) It may be used for new wiring in heritage homes without modification. C) It is prohibited for any new installations per the CEC. D) It can be used if the conductors are rated 90 °C. Answer: C Explanation: The CEC prohibits the use of knob-and-tube wiring in new installations due to fire-safety concerns. Question 56 A 240 V, 30 A electric water heater requires a dedicated circuit. Which of the following conduit fill calculations is correct for three 8 AWG THHN conductors in 3/4-in. EMT? A) 28 % fill – acceptable
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Answer: A Explanation: In a 3-wire system, the neutral (grounded conductor) is identified by white or gray insulation. Question 60 A residential panelboard has 20 spaces. According to the CEC, what is the maximum number of over-current protective devices that may be installed? A) 20 B) 22 C) 24 D) 30 Answer: C Explanation: The CEC allows a maximum of 120 % of the panelboard spaces for over-current devices, which for 20 spaces equals 24 devices. Question 61 Which of the following is the correct minimum spacing between a lighting fixture and a combustible ceiling surface? A) 0 mm (direct contact allowed) B) 25 mm C) 38 mm D) 50 mm Answer: C Explanation: The CEC requires a minimum of 38 mm clearance between a lighting fixture and combustible material to prevent overheating. Question 62 In a three-phase motor starter, which component provides the necessary overload protection? A) Thermal overload relay B) GFCI device C) AFCI breaker D) Surge protector Answer: A Explanation: Thermal overload relays are used in motor starters to protect against sustained over-current conditions.
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Question 63 Which of the following is the correct procedure for installing a “dead-front” panelboard in a commercial building? A) The dead-front must be removable for routine inspection. B) The dead-front must be permanently fixed and not removable without tools. C) The dead-front can be omitted if the panel is located in a restricted area. D) The dead-front must be painted a bright color for visibility. Answer: B Explanation: The CEC requires that dead-front panels be permanently secured to prevent accidental exposure to live parts. Question 64 A 120 V, 15 A branch circuit supplies a bathroom vanity light and a receptacle. Which of the following protection is required? A) AFCI only B) GFCI only C) Both AFCI and GFCI D) No special protection required Answer: B Explanation: The CEC mandates GFCI protection for bathroom receptacles; lights are covered by the same circuit. Question 65 Which of the following is the correct minimum size for a copper conductor supplying a 30 A, 240 V dryer if the conductor is 75 °C rated? A) 10 AWG B) 8 AWG C) 6 AWG D) 4 AWG Answer: B Explanation: Table 2 of the CEC shows that a 30 A circuit requires a minimum of 8 AWG copper when using 75 °C rated insulation. Question 66 Which of the following statements about “splices” in conduit systems is correct? A) Splices must be made with soldered connections only.
