The TSSA G3 exam is the written exam for Ontario's Gas Technician 3 certificate, the first of the province's gas technician certificates. It covers the nine training modules in TSSA's Gas Technician policy, from safety, tools and the properties of natural gas and propane through codes, acts and regulations, electricity, drawings and customer relations to piping and gas appliances, 180 suggested hours in all. Every question is multiple choice, and you need 75 per cent, TSSA's pass mark for Fuels exams. It is open book: you bring the Technical Standards and Safety Act, 2000, the Fuels regulations and Code Adoption Documents, CSA B149.1 and CSA B149.2, free of written notes. TSSA's prep guide gives no question count for the G3; it says its exams typically run from 50 to 165 questions, with up to 3.5 hours. Since March 16, 2026 you apply in the TSSA Client Portal and write on computer at a Prometric test centre.
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01What is the TSSA G3 certificate?
Gas Technician 3, or G3, is the first of Ontario's gas technician certificates. The classes are set out in O. Reg. 215/01 (Fuel Industry Certificates), a regulation under the Technical Standards and Safety Act, 2000. TSSA, the Technical Standards and Safety Authority, issues the certificates. G3 leads to G2, which covers appliances up to 400,000 Btuh, and then to G1. It is an Ontario certificate, not a Red Seal trade.
A G3 always works under supervision. Section 22 of O. Reg. 215/01 lets a G3 work under the general supervision of a G1, G2 or DA (domestic appliance technician) holder, who need not be on site but must be readily available. That applies to four kinds of work on natural gas and propane appliances within the supervisor's own scope, and only after the supervisor has documented and signed off, on TSSA's form, that the G3 has shown the skills:
- installing, testing, activating or purging gas piping or tubing under 2 1/2 inches in diameter, and its components, from the natural gas meter or propane service valve to the appliance control valve, including filling in the pressure test tag;
- reactivating an appliance that was installed or converted earlier;
- cleaning and lubricating appliances;
- cleaning, removing or replacing vent connectors, venting and draft control devices.
A G3 may not be the one to first activate a new appliance, or an appliance that has just been converted. Under direct supervision, with the supervisor on site close by and available to help, a G3 may do any work within the supervisor's certificate.
To move up to G2 or DA you need a valid G3 and either an accredited G3 training program, with its exam and practical parts, or at least 450 hours of documented G3 work under a G1, G2 or DA holder, declared on your employer's letterhead (TSSA policy, s. 6). From January 1, 2026, TSSA enforces that rule for G3 holders who got their certificate by challenge: they must show the 450 hours before they enrol in a G2 program.
02What is the G3 exam format?
TSSA's Certification Examination Preparation Guide (March 16, 2026) is the rule book for all its certification exams. For the G3 the main points are these: every question is multiple choice, the pass mark for Fuels exams is 75 per cent, and an exam has parts on the regulations and parts on the technical knowledge for the certificate.
TSSA's prep guide gives no question count or time limit for the G3. It says only that typical exams have between 50 and 165 questions, varying by certificate, and that some exam types allow up to 3.5 hours, with no extra time unless an accommodation was approved in advance. Other sites quote G3 counts and times; we found none of them in a TSSA document, so treat them as unconfirmed.
The prep guide and TSSA's Gas Technician policy give no question count per module either. The policy says challenge exam questions are drawn from a weighted database, and the prep guide says a candidate who fails gets a score breakdown by module, so the exam is organized by module, but neither document gives the weights.
If you fail, the wait before a Fuels re-write is 30 days. Multiple-choice results cannot be re-assessed; TSSA says it checks each electronically scored exam instead. TSSA's exam FAQ allows at most three attempts at a Fuels exam, and O. Reg. 215/01 s. 5 (4) says that after three failures in a row you must complete an accredited program before you write again.
03What can you bring into the G3 exam?
The G3 exam is open book. The prep guide's appendix gives one list for Gas Technician 2 and 3, gas piping fitter and domestic appliance technician:
- the Technical Standards and Safety Act, 2000;
- the Fuels regulations made under it, with their Code Adoption Documents (CADs);
- CSA B149.1, the Natural Gas and Propane Installation Code;
- CSA B149.2, the Propane Storage and Handling Code;
- if you want it, Supplement No. 1 to B149.2 (B149.2S1).
Bring your own books, because the test centre provides none. They must have no writing or notes in them; highlighting, page dividers and tabs are allowed. The guide names no edition for B149.1 or B149.2; the code editions section below explains why that matters.
Arrive at least 30 minutes early with valid government photo ID that shows your photo, signature, legal name and date of birth. No food or drink is allowed in the room. There are no breaks, except an emergency or a bathroom break if the invigilator permits one, and the clock keeps running; at a test centre you cannot leave the building once the exam starts. An electronic device or banned material found on you can be seized and used as evidence against you.
If you think a question is wrong, use the invigilator's procedure to challenge it during the exam and give your reference, such as the code clause. A TSSA technical expert reviews it and awards the mark if the challenge succeeds. You cannot raise it once the exam is over, and TSSA does not discuss questions with candidates afterwards.
04How do you book the exam and get your results?
Since March 16, 2026, you apply for TSSA exams in the TSSA Client Portal and write them on computer, in person, at Prometric test centres across Ontario. You pay when you apply. If you are eligible, TSSA emails you within 48 hours (10 to 15 business days where your experience has to be assessed), and that email explains how to book with Prometric. TSSA's announcement said candidates could write as soon as 3 days after applying, subject to seats. If you finished an accredited program, TSSA cannot book your exam until your training provider has sent in your Application for an Ontario Certificate of Qualification, and some providers arrange sittings for their own students.
Cancel or reschedule with Prometric at least 22 days before your exam date. Cancel later and you lose the fee; you get one reschedule. TSSA's exam pages describe in-person sittings only, and we found no online-proctored option.
Prometric emails your result within 24 hours, and TSSA sends an official result letter 48 to 72 hours after the exam. If you fail a multiple-choice exam written with Prometric, the score report that arrives within 24 hours breaks your result down by module. After a training-provider sitting, TSSA emails that breakdown within 3 to 4 weeks. Use it to aim your study for the re-write.
05How much does the G3 exam cost?
TSSA's Natural Gas and Hydrogen fee schedule sets these certification fees from May 1, 2026, plus HST where it applies:
| Fee | From May 1, 2026 |
|---|---|
| Challenge examination | $255.50 |
| Other examination | $89 |
| Certificate, initial or renewal (every two years) | $136 |
The schedule says exam fees are charged for every exam and every re-write, pass or fail, so each attempt costs the full fee again. A certificate runs until the second anniversary of your date of birth after it is issued, and a renewal costs the same $136 (TSSA policy, s. 3).
06Can you write the G3 without a course?
Yes. TSSA's policy lets a person who has never held a certificate challenge only two exams, the G3 and the oil burner technician 3 (OBT-3), so G3 is the one gas certificate you can get without first taking a course. The challenge route has two parts:
- the written exam, with questions drawn from TSSA's weighted database;
- a practical skills assessment by a TSSA Training and Certification Advisor, against the practical standards in the approved curriculum. A virtual assessment needs exceptional circumstances and the Director's written permission.
You must finish both within one year of passing the written exam. A G3 challenge needs no approval letter, so the year starts on the day you pass. The policy adds that challenge and pre-exam courses are not accredited programs. If you fail the exam three times in a row, O. Reg. 215/01 s. 5 (4) requires an accredited program before you write again, and TSSA's policy says that means a full program with theory and practical training.
The other route is an accredited G3 program. There you need at least 75 per cent in each curriculum module, 75 per cent on the TSSA exam and 75 per cent on the practical evaluation, at least 80 per cent attendance, and the exam and practical passed within a year of finishing the program (TSSA policy, s. 6).
07What do the nine G3 modules cover?
TSSA's Gas Technician/Oil Burner Technician Policies and Procedures (September 2025, s. 19 and 21) lists nine modules for G3, with 180 suggested program hours. The curriculum behind them was drawn up by joint TSSA and industry task forces in 1996 and updated in 2002; accredited training providers teach from it, and we found no public copy of its objectives. The summaries below come from the 50 objectives in TicketPrep's own question bank, which we built from public sources: college course outlines, Ontario's regulations on e-Laws, TSSA documents and manufacturers' manuals. They are our reading, not TSSA's objectives. CSA Group's Gas Trade 3 package of training units covers units 1 to 9 plus Unit 4A, an Ontario supplement to the codes unit.
Module 1: Protect Self and Others
Safety on gas jobs: your rights and duties, and those of employers and supervisors, under Ontario's Occupational Health and Safety Act, and the roles of Ministry of Labour inspectors, joint health and safety committees, WSIB and TSSA; choosing protective equipment; lifting appliances and cylinders; ladders, roofs, attics and low spaces where heavier-than-air gas can collect; locking out gas and power before service; WHMIS labels and safety data sheets; and fire safety, from extinguisher classes and hot work to a fire fed by leaking gas.
Free Module 1 practice questions: Safety, WHMIS & Fire →
Module 2: Fasteners, Hand Tools and Power Tools
Choosing fasteners and anchors for wood, masonry, concrete and steel, and pipe supports; using and caring for hand tools; power tools, with double insulation, grounding and ground-fault protection; tapes, levels and squares; manometers and gauges read in inches of water column and psig; combustion analyzers, CO meters and combustible-gas detectors zeroed in fresh air; and electrical testers such as multimeters, clamp-on ammeters and microammeters, with category ratings and proving a tester before and after use.
Free Module 2 practice questions: Fasteners & Tools →
Module 3: Properties, Characteristics, Safe Handling of Propane and Natural Gas
How the two fuel gases behave: composition, specific gravity and where a leak goes, propane's boiling point and its vapour pressure rising with temperature, heating values in MJ/m3 and Btu/ft3, and odorants and why smell alone is not a safe test; combustion, flammable limits, ignition temperature, primary and secondary air, and carbon monoxide from incomplete burning; the hazards of CO, asphyxiation, explosion and liquid propane; finding and responding to leaks, with readings in per cent of the lower limit; and handling propane cylinders and tanks, including Ontario's rules on who may handle propane.
Free Module 3 practice questions: Propane & Natural Gas →
Module 4: Installation Codes, Acts and Regulations
The largest module in our bank. It covers the regulators and testing organizations and what approved means in Ontario; the Technical Standards and Safety Act, 2000; O. Reg. 212/01 (Gaseous Fuels), including unacceptable conditions, immediate hazards and reporting an incident; O. Reg. 215/01 certificate scopes and supervision; the Gaseous Fuels CAD and its Ontario amendments; how B149.1-25 is laid out and how to find a requirement in it; B149.2 and O. Reg. 211/01 for propane; and the G3 sign-off, progression and due diligence.
Free Module 4 practice questions: Codes, Acts & Regulations →
Module 5: Introduction to Electricity
Electrical safety and the wiring a gas technician may do, from an existing protected branch circuit to the appliance; voltage, current, resistance, Ohm's law and power; series and parallel circuits and open, short and ground faults; magnets, solenoids, relays and gas valve operators; AC and DC, the 120 V supply and transformers down to 24 V control circuits; thermocouples and thermopiles; and taking voltage, current, resistance, millivolt and microamp readings to find a fault.
Free Module 5 practice questions: Electricity →
Module 6: Technical Manuals, Specifications, Schematics, Drawings and Graphs
Reading what a technician works from: certified installation instructions, rating plates and specifications; orthographic, isometric and detail drawings; ladder schematics and wiring diagrams, tracing a control sequence; graphs, charts and tables, including interpolation; and imperial and SI units, from inches of water column and psig to kPa, Btuh, kW and gas flow per hour.
Free Module 6 practice questions: Manuals & Drawings →
Module 7: Customer Relations
Working in people's homes: professional conduct, listening, and explaining work, findings and safety notices plainly; handling upset customers, complaints and cultural differences; and protecting floors, finishes and furnishings, then cleaning up.
Free Module 7 practice questions: Customer Relations →
Module 8: Introduction to Piping and Tubing Systems
Gas piping and tubing up to the appliance: steel pipe, copper and aluminum tubing, polyethylene underground, CSST and appliance connectors; threaded and flared joints, fittings, manual shut-off valves and the tools; routing, support, corrosion protection, Ontario's depth of cover and drip pockets; sizing by load and length from a given table; pressure and leak tests and Ontario's pressure test tag; purging and activating lines; and water piping at water heaters and boilers. It is the work behind the first G3 function under general supervision.
Free Module 8 practice questions: Piping & Tubing →
Module 9: Introduction to Gas Appliances
How residential gas appliances work: ratings, natural draft, fan-assisted, power-vent and direct-vent types, and Ontario limits on where they go; burners and flame faults; standing, intermittent and interrupted pilots, spark and hot-surface ignition, thermocouples and flame rectification; gas valves, regulators, operating and limit controls; venting, draft, spillage, chimney checks and combustion air; converting between natural gas and propane; and shutting down, cleaning, lubricating and reactivating an appliance.
Free Module 9 practice questions: Gas Appliances →
08Which code editions apply to the G3 exam?
In Ontario, the gas codes take legal effect through O. Reg. 223/01 and TSSA's Code Adoption Documents, and where the CAD and a code conflict, the CAD prevails. Two CAD amendments changed the codes in 2026:
- FS-279-26, published April 2, 2026 and in effect from June 1, 2026, adopts CSA B149.1-25 (and B149.3-25) with Ontario amendments and replaces the May 2021 amendment that adopted B149.1-20;
- FS-281-26, published April 8, 2026 and in effect from June 8, 2026, adopts CSA B149.2-25 for propane storage and handling.
TSSA's prep guide lists B149.1 and B149.2 without an edition, and we found no TSSA notice saying when G3 exam questions moved to the 2025 editions. CSA describes its own online Gas Trade practice exam as updated to the 2020 edition of B149.1, and we found no CSA Gas Trade training material described as updated to B149.1-25.
Clause numbers can move from one edition to the next, so a reference from older notes may point to the wrong place in a 2025 book. Before you buy, ask your training provider or TSSA's certification and examinations department (certandexams@tssa.org) which edition to bring. Whichever you bring, read the current CAD amendment with it. It is a free PDF on TSSA's site, and it changes definitions and clauses on piping, appliances and venting, makes Annexes C and G mandatory, and adds Ontario Annexes P to S: piping in rocky areas, mandatory safety checks on residential natural-draft boilers, an existing B vent installed outdoors, and mobile food service equipment.
09How should you study for an open-book code exam?
With the books on the desk, the skill to build is finding a rule fast and reading it correctly, not memorising every figure. TSSA's prep guide gives no G3 time limit, so do not plan on having time to search for every answer. These steps follow from the rules above:
- Learn the layout of B149.1. The CAD's own amendments show it: definitions in Section 3, general requirements in Section 4, piping and tubing in Section 6, appliances in Section 7, venting and air supply in Section 8, then the annexes. Tab each section and the Ontario annexes.
- Keep the CAD beside the code. Where Ontario has replaced or added a clause, highlight or tab that clause so you know to check the CAD. Written notes are not allowed, so the tabs have to do the work.
- Know which document governs. The Act and its regulations, the CAD, the codes and the manufacturer's certified instructions each hold different rules. Ontario's amended clause 4.1.5 says that where the certified instructions and B149.1 conflict, the more stringent applies.
- Know the regulations by subject. O. Reg. 212/01 holds unacceptable conditions and incident reporting, O. Reg. 215/01 holds certificate scopes and supervision, and O. Reg. 211/01 holds propane handling. All three are free on e-Laws.
- Practise lookups against the clock. Pick a topic, find the clause, read it to the end, and time yourself. Do it until the common lookups take seconds.
The listed books are codes and laws. They do not explain Ohm's law, a thermocouple or a lifting flame, so the theory in Modules 3, 5, 6 and 9, and the tools and safety in Modules 1 and 2, need ordinary study. TSSA's FAQ says it provides no study materials, guides or practice exams, so plan on a course, the CSA units or other material for those. If you do fail, start the re-write study from your module breakdown.
10How does TicketPrep's G3 practice test work?
Our timed G3 practice exam is 100 questions in 180 minutes, with 75 per cent to pass. The 75 per cent is TSSA's Fuels pass mark. The 100 questions and 180 minutes are our choice: TSSA does not publish a G3 question count that we could find, and its prep guide gives only the 50 to 165 question range and up to 3.5 hours across its exams.
The bank has 550 questions, 400 Standard and 150 Advanced, written to the 2025 code editions as adopted in Ontario, each one verified against the public sources noted with it. Each practice exam draws from the nine modules in the proportions below. They are our estimate from course hours and the open-book code-lookup style, not TSSA's weights.
| Module | Questions in our bank | Questions per 100-question practice exam |
|---|---|---|
| Module 1: Protect Self and Others | 38 | 8 |
| Module 2: Fasteners, Hand Tools and Power Tools | 28 | 6 |
| Module 3: Propane and Natural Gas | 70 | 12 |
| Module 4: Codes, Acts and Regulations | 124 | 22 |
| Module 5: Electricity | 68 | 12 |
| Module 6: Manuals, Drawings and Graphs | 30 | 6 |
| Module 7: Customer Relations | 14 | 3 |
| Module 8: Piping and Tubing | 106 | 18 |
| Module 9: Gas Appliances | 72 | 13 |
| Total | 550 | 100 |
You can see the style before you pay: the G3 practice test page has five sample questions, the free G3 practice questions page has ten more, and each module above links to five free questions for that module.
11Questions people ask
- How many questions are on the TSSA G3 exam?
- TSSA's Certification Examination Preparation Guide gives no question count for the G3. It says only that typical TSSA exams have between 50 and 165 questions, varying by certificate, with up to 3.5 hours for some exam types. Every question is multiple choice and the Fuels pass mark is 75 per cent. We found no TSSA document that confirms the G3 counts quoted on other sites.
- What is the pass mark for the G3 exam?
- 75 per cent, the pass mark TSSA's prep guide sets for all Fuels exams. If you fail, you can re-write after 30 days and each re-write is billed again. TSSA's exam FAQ allows at most three attempts, and after three failures in a row O. Reg. 215/01 requires a full accredited program before you write again.
- Is the G3 exam open book?
- Yes. You may bring the Technical Standards and Safety Act, 2000, the Fuels regulations and their Code Adoption Documents, CSA B149.1 and CSA B149.2, plus the optional supplement to B149.2. The books must have no writing or notes in them, but highlighting, page dividers and tabs are allowed. You bring your own; the test centre provides none.
- Can I challenge the G3 without taking a course?
- Yes. G3 is the only gas certificate a person who has never held a certificate may challenge. You pass the written exam, then a hands-on practical skills assessment with a TSSA Training and Certification Advisor, and you must finish both within one year of passing the exam. The challenge exam fee is $255.50 from May 1, 2026, plus HST where it applies.
- Where do you write the G3 exam?
- Since March 16, 2026 you apply and pay in the TSSA Client Portal, then book a computer-based exam with Prometric and write it in person at a Prometric test centre in Ontario. Prometric emails your result within 24 hours, and TSSA sends an official letter 48 to 72 hours after the exam. Cancel or reschedule at least 22 days ahead, and only one reschedule is allowed.
12Sources
- TSSA: Certification Examination Preparation Guide (March 16, 2026, PDF): multiple choice, the 50 to 165 question range and up to 3.5 hours, the 75% Fuels pass mark, the 30-day re-write wait, no re-assessment of multiple-choice results, the breakdown by module after a fail, exam-day rules, challenging a question, and the permitted materials for Gas Technician 3. Accessed October 15, 2026.
- TSSA: Gas Technician/Oil Burner Technician Policies and Procedures (September 2025, PDF): the nine G3 modules and 180 suggested hours (s. 19 and 21), the 1996 curriculum updated in 2002, the accredited-program requirements (s. 6), the 450-hour route to G2 and DA (s. 6), the challenge process and its one-year limit (s. 5 and 7), and certificate expiry (s. 3). Accessed October 15, 2026.
- TSSA: FAQs, Examinations and Certification: Prometric sittings, eligibility emails, cancelling and rescheduling, results within 24 hours and the official letter, score reports by module, three attempts at a Fuels exam, and no TSSA study materials or practice exams. Accessed October 15, 2026.
- TSSA: Exam and Certification Improvements Go Online in March 2026: the Client Portal and computer-based exams at Prometric test centres from March 16, 2026, and writing as soon as 3 days after applying. Accessed October 15, 2026.
- TSSA: New Requirement for Fuels G2 Enrolment, Proof of G3 Work Experience for Challenge Certificate Holders: the 450 hours of G3 work experience required from January 1, 2026. Accessed October 15, 2026.
- TSSA: Natural Gas and Hydrogen Fee Schedule (effective May 1, 2026, PDF): the challenge examination, other examination and certificate fees, HST, and the fee for every exam and re-write. Accessed October 15, 2026.
- O. Reg. 215/01, Fuel Industry Certificates (e-Laws): the certificate classes, s. 5 (4) on three failed attempts, and s. 22 on G3 work under general and direct supervision. Accessed October 18, 2026.
- O. Reg. 223/01, Codes and Standards Adopted by Reference (e-Laws): the regulation under which TSSA's Code Adoption Documents adopt the gas codes. Accessed October 18, 2026.
- TSSA: Gaseous Fuels Code Adoption Document Amendment FS-279-26 (April 2, 2026, PDF): the adoption of B149.1-25 with Ontario amendments from June 1, 2026, the CAD prevailing in a conflict, the sections it amends, clause 4.1.5, Annexes C and G, and Ontario Annexes P to S. Accessed October 15, 2026.
- TSSA: Propane Code Adoption Document Amendment FS-281-26 (April 8, 2026, PDF): the adoption of B149.2-25 from June 8, 2026. Accessed October 15, 2026.
- CSA Group: Gas Trade Training Materials: the Gas Trade 3 package of units 1 to 9 with the Unit 4A Ontario supplement. Accessed October 15, 2026.
- CSA Group: Gas Trade Practice Exam (product page): CSA's practice exam described as updated to the 2020 edition of B149.1. Accessed October 15, 2026.
The exam rules were read in TSSA's own documents and pages as saved on October 15, 2026, and O. Reg. 215/01 on e-Laws on October 18, 2026. Where a TSSA document does not state a figure, such as the G3 question count or the module weights, we say so instead of filling it in. The module summaries are our own reading of public sources, not TSSA's curriculum, and no CSA code text is reproduced on this page. TSSA is the final word on its exams; if you find one of ours out of date, tell us.
Related: TSSA G3 practice test · Free TSSA G3 practice questions · How our questions are made · All guides
13Practice for this exam
TicketPrep G3 practice tests cover all nine modules and all 50 of our objectives, and every answer is explained, all four options. You can try five sample questions with no account. The G3 Exam Pass is $69 one time for 120 days, and All-Access at $89 includes it along with the Red Seal trades and 4th Class Power Engineering.
Ten free questions per trade, no account: free practice questions. How our questions are written and checked: how our questions are made.