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Ontario G3 Gas Technician exam preparation

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Ontario G3 Gas Technician Exam: Topics, Format and How to Prepare

What the G3 exam covers, what it looks like on the day, and a study plan that works — with free practice questions for every topic.

The format

The Ontario G3 exam is 165 questions over 3 hours 30 minutes, sat in one session with no pausing. The pass mark is commonly cited as 75%; practising to 80% leaves room for nerves and for wording you have not seen before.

The nine topics

Each links to what that area tests, how to approach it, and free sample questions.

Gas Properties and CombustionFuel properties, combustion air, flame characteristics and the numbers examiners keep coming back to.Gas Code and Piping (B149.1)CSA B149.1 installation requirements, pipe materials, joints, supports and sizing.Electricity and ControlsCircuits, meters, wiring, transformers and the electrical theory the G3 exam expects.Appliances and Heat TransferFurnaces, boilers, heat exchangers, temperature rise and appliance servicing.Safety and Workplace PracticesOccupational health and safety, personal protection, fire extinguishers and site conduct.Venting and Combustion ProductsVent systems, categories, draft, and safely removing the products of combustion.Regulations and TSSAThe Technical Standards and Safety Act, certification, inspection powers and penalties.Controls and Ignition SystemsPilots, ignition types, safety shut-off, thermocouples and flame supervision.Tools, Instruments and MeasurementsManometers, gauges, conversions, drawings and the instruments of the trade.

Guides worth reading

Pipe sizing, step by stepThe four-step method and the ten scenarios it covers. Gas properties and conversionsThe numbers that appear on every attempt. Fire extinguisher classesAll five, and what each is used on. Venting and categoriesCategories I to IV and what each vent demands. Becoming a gas technicianHow G3, G2 and G1 fit together in Ontario. Practice questionsFree questions with answers, every topic.

A study plan that works

  1. Find out where you stand. Take a mock exam before studying anything. It is uncomfortable and it saves weeks.
  2. Work one topic at a time. Reading the manual front to back feels productive and rarely is.
  3. Re-drill what you got wrong until you know why the answer is right, not merely which letter it was.
  4. Sit a full timed exam before the real one. Three and a half hours is longer than it sounds, and pacing is a skill of its own.

Common questions

What is the Ontario G3 gas technician certification?

G3 is the entry-level gas technician certification in Ontario, administered by TSSA. It permits work on gas appliances up to 400,000 BTU/h under supervision, and is the first step toward G2 and G1.

What score do you need to pass the G3 exam?

The G3 exam is commonly cited as requiring 75%. Aiming for 80% in practice leaves a buffer for exam-day nerves and unfamiliar wording. Confirm the current requirement with TSSA or your training provider.

How many questions are on the G3 exam?

The Ontario G3 exam is 165 questions over 3 hours 30 minutes, sat in one session without pausing.

What topics does the G3 exam cover?

The syllabus spans 9 areas: Gas Properties & Combustion, Gas Code & Piping, Electricity & Controls, Appliances & Heat Transfer, Safety & Workplace, Venting & Combustion, Regulations & TSSA, Controls & Ignition, Tools & Measurements.

Which codes does the G3 exam draw on?

CSA B149.1, the Natural Gas and Propane Installation Code, is the main one, with B149.2 for propane storage and handling. The Technical Standards and Safety Act and the Occupational Health and Safety Act also appear.

What is the best way to study for the G3 exam?

Work topic by topic rather than reading cover to cover, take full-length timed practice tests to find your gaps, and re-drill every question you get wrong until you understand why the answer is what it is. Most people underestimate the code sections.

Try the free 20-question mock exam →