What the 309A exam is
Electrician, Construction and Maintenance (trade code 309A) is a compulsory trade in Ontario under the Building Opportunities in the Skilled Trades Act, 2021. To work in the trade legally you must hold a Registered Training Agreement, a Provisional Certificate of Qualification or a Certificate of Qualification (C of Q), and appear on the Skilled Trades Ontario Public Register. The apprenticeship is set at 9,000 hours: 8,160 hours on the job and 840 hours of in-school training.
When you finish your apprenticeship, or are approved through a Trade Equivalency Assessment, you write the certifying exam. Passing it leads to your C of Q from Skilled Trades Ontario. In Ontario the trade is part of the Interprovincial Red Seal Program under the national title Construction Electrician, and the Red Seal exam is the national standard for the trade.
| Part of the exam | What to expect |
|---|---|
| Questions | 100 multiple-choice questions on the Red Seal Construction Electrician exam, each worth one mark |
| Options | Four choices, exactly one correct, with no trick questions |
| Writing time | Four hours |
| Pass mark | 70% |
| Supplied at the exam | A formula sheet, an acronym list, a calculator if needed, and code book information where required |
| Language | English or French in Ontario |
| If you do not pass | In Ontario, a 30-day waiting period before you can rewrite, and the exam fee is paid again |
The Red Seal program says about 5 to 15% of questions test knowledge and recall, 60 to 70% test procedures and application, and 20 to 30% test critical thinking, such as working through a calculation or a code problem. Always check your Authorization to Test letter for the details of your own sitting.
How the exam is weighted
Red Seal exam questions come from the Red Seal Occupational Standard for the trade. The standard is split into five major work activities, and the official exam breakdown gives each one a set number of questions. Our sections follow the same five activities, and our 100-question mock exams use the same weighting.
| Major work activity | Red Seal questions | What it covers |
|---|---|---|
| A. Common occupational skills | 11 | Safety, lockout, tools and test equipment, commissioning, mentoring |
| B. Generation, distribution and services | 28 | Services and metering, protection devices, bonding and grounding, transformers, generators, renewables, high voltage |
| C. Wiring systems | 30 | Raceways, conductors and cables, branch circuits, HVAC, electric heat, exit and emergency lighting, cathodic protection |
| D. Motors and control systems | 21 | Starters and controls, drives, motors, PLCs and automated controls |
| E. Signalling and communication systems | 10 | Fire alarm, communication cabling, security and integrated building controls |
Calculations you should be fast at
The formula sheet you get on exam day lists the formulas, but it does not tell you which one to use. Practise until these feel automatic:
- Ohm's law and power. E = I x R, P = E x I, P = I squared x R and P = E squared / R, including what happens when a heater runs below its rated voltage.
- Three-phase. Line and phase values in wye and delta (the 1.73 factor), kVA, and true power with power factor.
- Transformers. Turns ratio, full-load current, and available short-circuit current from percent impedance.
- Motors. Synchronous speed from poles and frequency, slip, horsepower to watts, and current from efficiency and power factor.
- Voltage drop and AC circuits. Two-wire and three-phase voltage drop, reactance, impedance and power factor.
Safety rules worth knowing cold
Ontario's construction projects regulation (O. Reg. 213/91) sets out who may do electrical work, how a power supply must be locked out and tagged, what goes on the tag, the minimum distances from overhead lines, and the rules for rubber gloves, extension cords and GFCI protection outdoors. The Occupational Health and Safety Act sets out your duties as a worker and your right to refuse unsafe work. Where a safety answer comes from a regulation, our explanation names the section.
How to prepare
Start with the official Red Seal self-assessment and the exam breakdown to find your weaker areas. Use the occupational standard, not only your college textbooks, because the exam covers the full scope of the trade across Canada. Then drill one section at a time here, read every explanation, and finish with full timed mocks of 100 questions in four hours. Aim to score well above 70% in practice so a few hard questions on the day do not sink you.
Aptitude Tests Canada is an independent practice platform. We are not affiliated with or endorsed by Skilled Trades Ontario, the Red Seal Program, the Electrical Safety Authority or the Government of Ontario. Our questions are original practice questions, not real exam questions, and they do not reproduce the Canadian Electrical Code.
Three worked examples
One question from different sections of the full pack, with the answer and explanation.
O. Reg. 213/91 lists what must appear on the tag placed on a disconnected power supply. Which of these is NOT on that list?
- Why the equipment was disconnected
- The name of the person who disconnected it
- The date it was disconnected
- The circuit's voltage and ampere rating
In a single-phase 120/240 V three-wire service, what voltage is measured between the two ungrounded (line) conductors?
- 120 V
- 208 V
- 240 V
- 0 V
A 1,500 W heater is rated for 240 V. How much current does it draw at rated voltage?
- 12.5 A
- 6.25 A
- 3.13 A
- 0.16 A