Ontario Master Electrician (ESA) Exam Prep

Ontario master electrician (ESA) practice questions with answers

8 free questions with answers and explanations. Each one passed an independent accuracy review, and each is labeled with where it comes from. Open a question to check your answer.

1. Question 1 · Business & Project Management · Contractor

   General CEC 2024 practice, the edition the Ontario exam uses

   On a fast-tracked project a contractor has a certified luminaire approved as a dry-location fixture but, to avoid a redesign delay, plans to install it in a wet exterior canopy location. The product is genuinely certified. Under CEC Rule 2-024, is installing it in the wet location acceptable solely because the product carries a certification mark?

   1. A.Yes — a valid certification mark means the equipment may be used in any location the contractor needs.
   2. B.Yes — the certification mark satisfies the Code, and location ratings are only manufacturer recommendations.
   3. C.No — Rule 2-024 requires equipment to be of a kind, type, and rating approved for the specific purpose, so a dry-location-rated luminaire may not be installed in a wet location.
   4. D.No — but only because a second certification mark from a different agency would be required for outdoor use.
   Show the answer and explanation

   Answer: C. No — Rule 2-024 requires equipment to be of a kind, type, and rating approved for the specific purpose, so a dry-location-rated luminaire may not be installed in a wet location.

   CEC Rule 2-024 requires that equipment be approved and be of a kind, type, and rating approved for the specific purpose for which it is employed; approval is purpose- and rating-specific, not a blanket license. The correct answer is that a dry-location-rated luminaire may not be installed in a wet location, because using it outside its approved purpose violates Rule 2-024 even though the product is certified. Location/environment ratings are part of the approval, not optional manufacturer advice.

   Reference: CEC 2024 Rule 2-024

2. Question 2 · Dwelling Service Load (CEC) · Master

   General CEC 2024 practice, the edition the Ontario exam uses

   A 120 V, 15 A branch circuit serving receptacles runs 40 m from the panelboard. The measured voltage drop is 4.2 V. Does this installation comply with CEC Rule 8-102?

   1. A.Yes — 4.2 V drop on 120 V is only 3.5%, within the 5% combined path limit
   2. B.No — CEC requires 0% voltage drop on all circuits under 50 m
   3. C.Yes — the 3% limit applies only to feeders, not branch circuits
   4. D.No — 4.2 V exceeds the mandatory 3% branch circuit limit of 3.6 V on 120 V
   Show the answer and explanation

   Answer: D. No — 4.2 V exceeds the mandatory 3% branch circuit limit of 3.6 V on 120 V

   Per CEC Rule 8-102(1): CEC Rule 8-102(1) limits branch-circuit voltage drop to 3%. On a 120 V circuit, 3% = 3.6 V. The measured 4.2 V drop (3.5%) exceeds the mandatory limit, so the installation does not comply.

   Reference: CEC Rule 8-102(1)

3. Question 3 · Voltage Drop · Master

   General CEC 2024 practice, the edition the Ontario exam uses

   A single-phase 240 V branch circuit must carry 24 A to a load 50 m (164 ft) away. The designer wants the voltage drop held to the 3% recommendation. Using the CEC imperial method with copper RW90 conductors (K = 12.9), what is the SMALLEST conductor that keeps voltage drop at or below 3%? (Cmil: No. 10 = 10 380; No. 8 = 16 510; No. 6 = 26 240.)

   1. A.No. 10 AWG copper
   2. B.No. 8 AWG copper
   3. C.No. 6 AWG copper
   4. D.No. 4 AWG copper
   Show the answer and explanation

   Answer: B. No. 8 AWG copper

   The 3% target on 240 V is 7.2 V. Using VD = (2 x K x I x L) / cmil with L = 164 ft, I = 24 A, K = 12.9: For No. 10 (10 380 cmil) VD = (2 x 12.9 x 24 x 164) / 10 380 = 9.79 V = 4.08%, which exceeds 3%. For No. 8 (16 510 cmil) VD = (2 x 12.9 x 24 x 164) / 16 510 = 6.15 V = 2.56%, which is within 3%. No. 8 AWG is therefore the smallest copper conductor that satisfies the limit. CEC Rule 8-102 allows upsizing a conductor beyond its ampacity requirement to control voltage drop; when a conductor is upsized for this reason, Rule 10-616(3) governs how the bonding conductor is then sized. Option B is correct.

   Reference: CEC Rule 8-102

4. Question 4 · Special Occupancies · Contractor

   General CEC 2024 practice, the edition the Ontario exam uses

   An industrial process area is classified as a Class I location where a flammable gas atmosphere is NOT likely to occur during normal operation and, if it does occur, will exist only for a short period. Under the CEC zone system, how must this area be classified?

   1. A.Zone 0
   2. B.Zone 1
   3. C.Zone 2
   4. D.Zone 22
   Show the answer and explanation

   Answer: C. Zone 2

   Under Rule 18-006, Class I (gas) locations are divided into Zone 0, Zone 1, and Zone 2 based on the frequency and duration of the explosive gas atmosphere. Zone 2 is the correct classification because it is defined as a location in which an explosive gas atmosphere is not likely to occur in normal operation and, if it does occur, will exist for a short time only. This drives the permitted wiring methods and equipment selection.

   Reference: CEC 2024 Rule 18-006

5. Question 5 · Business & Project Management · Contractor

   General CEC 2024 practice, the edition the Ontario exam uses

   To save cost on a project, a supplier offers an electrical contractor a control enclosure imported directly from overseas that carries only the foreign manufacturer's house label and no recognized certification or field-evaluation mark accepted in the jurisdiction. Under CEC Rule 2-024, may the contractor install this equipment as-is in the electrical installation?

   1. A.Yes, because the contractor, as the responsible licence holder, may self-certify equipment they choose to install.
   2. B.Yes, provided the equipment is installed strictly per the manufacturer's instructions.
   3. C.No — electrical equipment used in the installation must be approved (certified or otherwise accepted by the regulatory authority) and of a kind, type, and rating approved for the specific purpose.
   4. D.No, unless the project's consulting engineer signs a letter accepting liability for the uncertified equipment.
   Show the answer and explanation

   Answer: C. No — electrical equipment used in the installation must be approved (certified or otherwise accepted by the regulatory authority) and of a kind, type, and rating approved for the specific purpose.

   CEC Rule 2-024 requires that electrical equipment used in an installation within the jurisdiction of the inspection department be approved and be of a kind, type, and rating approved for the specific purpose for which it is employed. The correct answer is therefore that the equipment must be approved (certified or otherwise accepted by the regulatory authority) and approved for the specific purpose, so a unit bearing only a foreign house label with no recognized certification or accepted field evaluation cannot be installed as-is. The contractor's licence does not grant authority to self-certify products.

   Reference: CEC 2024 Rule 2-024

6. Question 6 · Licensing & Exam Administration · Contractor

   General CEC 2024 practice, the edition the Ontario exam uses

   Exam questions frequently turn on who the CEC calls the "authority having jurisdiction." In the context of the Canadian Electrical Code as adopted in a province, the authority having jurisdiction is best understood as:

   1. A.The contractor's own designated master electrician on the project.
   2. B.The CSA Group technical committee that writes the code text.
   3. C.The supply utility's metering department.
   4. D.The regulatory authority (and its inspectors/inspection department) responsible for administering and enforcing the code in that jurisdiction.
   Show the answer and explanation

   Answer: D. The regulatory authority (and its inspectors/inspection department) responsible for administering and enforcing the code in that jurisdiction.

   Section 0 of the CEC defines the "authority having jurisdiction" as the regulatory authority, or its inspection department/inspectors, responsible for the administration and enforcement of the code where it is adopted. The correct option matches this: it is the enforcing regulator/inspection authority. The standards-writing committee, the utility metering group, and the contractor's own master electrician are not the AHJ.

   Reference: CEC 2024 Section 0 (definition of "authority having jurisdiction")

7. Question 7 · Dwelling Service Load (CEC) · Master

   General CEC 2024 practice, the edition the Ontario exam uses

   Under CEC Rule 8-200, which load type was added in recent code cycles specifically to address new residential technology, requiring it to be included in dwelling service calculations?

   1. A.Solar photovoltaic generation equipment
   2. B.Smart home control systems
   3. C.Heat pump water heater
   4. D.Electric vehicle charging equipment
   Show the answer and explanation

   Answer: D. Electric vehicle charging equipment

   Per CEC Rule 8-200(1)(a)(vi): CEC Rule 8-200(1)(a)(vi) specifically adds EV charging equipment as a required load component in the dwelling service load calculation. This sub-rule addresses the growing prevalence of residential EV chargers.

   Reference: CEC Rule 8-200(1)(a)(vi)

8. Question 8 · Electrical Theory & Ohm's Law · Master

   General CEC 2024 practice, the edition the Ontario exam uses

   A single-phase 240 V, 2-wire branch circuit supplies a 90 A continuous load through size 2 AWG copper conductors. The one-way run is 50 m. Using the CEC imperial voltage-drop method (K = 12.9 ohm-cmil/ft for copper, 66 360 cmil for 2 AWG), what is the approximate voltage drop, and does it satisfy the branch-circuit limit?

   1. A.About 11.5 V (4.8%) - not acceptable, it exceeds the 3% branch limit
   2. B.About 2.9 V (1.2%) - acceptable, well within the 5% overall limit
   3. C.About 1.8 V (0.7%) - acceptable, far below any limit
   4. D.About 5.7 V (2.4%) - acceptable, since it is at or below 3% on the branch circuit
   Show the answer and explanation

   Answer: D. About 5.7 V (2.4%) - acceptable, since it is at or below 3% on the branch circuit

   The CEC voltage-drop method (the imperial K-constant form of the resistance calculation referenced under Rule 8-102) for a single-phase, 2-wire circuit is VD = (2 x K x I x D) / cmil, where D is the one-way length in feet. Converting 50 m gives about 164 ft, so VD = (2 x 12.9 x 90 x 164) / 66 360, which is about 5.7 V, or 2.4% of 240 V. The correct option is 'About 5.7 V (2.4%) - acceptable, since it is at or below 3% on the branch circuit.' Rule 8-102 caps voltage drop at 3% on a feeder or a branch circuit and at 5% from the supply to the point of utilization; 2.4% clears the branch limit. The factor of 2 accounts for both the supply and return conductors of the loop.

   Reference: CEC Rule 8-102; imperial voltage-drop method VD = (2 x K x I x D)/cmil, K = 12.9 (Cu)