Gas Technician (TSSA) · Ontario G3
Five TSSA G3 practice test questions, answers included.
Five practice questions from five of the nine modules of the Ontario Gas Technician 3 exam: gas properties, the gaseous fuels regulation, electricity, piping tests and appliance controls. Pick an answer, then open the explanation. Every question in the bank explains all four options, not just the right one.
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Take propane's flammable range as 2.1 % to 9.5 % and natural gas's as 5 % to 15 %. Each gas leaks at the same steady rate into one of two identical closed rooms and mixes evenly with the air as it leaks. Which room reaches a flammable mixture first?
- The propane room, as its lower limit needs under half the gas
- The natural gas room, as its upper limit of 15 % is higher
- Both at once, as gas enters each room at the same rate
- The natural gas room, as the lighter gas mixes with air faster
Show the answer
A. Correct. A propane mixture becomes flammable at 2.1 % against 5 % for natural gas, so at the same leak rate the propane room gets there first, after 2.1 ÷ 5 = 0.42 of the leaked volume natural gas needs.
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A G.2 servicing a furnace in a townhouse finds an unacceptable condition that he judges to be an immediate hazard. Which order of actions does O. Reg. 212/01 s. 13(3) require?
- Give the user written notice first, and shut off only if the user agrees
- Promptly notify the distributor orally, then shut off the gas once it agrees
- Shut off the gas first, then promptly notify the distributor and the user
- Shut off the gas, then notify the distributor in writing within 90 days
Show the answer
C. Correct. Section 13(3) puts the shut-off first: (a) immediately shut off the gas, (b) promptly give the distributor oral notice of the shut-off, (c) promptly give the user written notice describing the hazard and directing no use, plus (d) written notice to the distributor within 14 days and (e) a notice affixed to the appliance.
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A 30 Ω gas valve coil and a 60 Ω zone damper coil are connected in parallel across a 24 V secondary. Treating both coils as resistances, what is their combined resistance?
- 0.050 Ω
- 20 Ω
- 45 Ω
- 90 Ω
Show the answer
B. Correct. 1/R = 1/30 + 1/60 = 0.050, so R = 20 Ω; or (30 × 60) ÷ (30 + 60) = 20 Ω. Parallel resistance is always less than the smallest branch, because each branch adds another path for current.
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During the pressure test of new piping at a cottage, the gauge falls, and leak-detection solution shows bubbles at one union. The G.3 tightens the union, and the solution then shows no bubbles. What comes next?
- Retest only the union with a second coat of solution
- Record a pass, since the leaking union is now sealed tight
- Extend the first test by the minutes already used
- Repeat the full test with the repaired union in place
Show the answer
D. Correct. The test proves the whole system, not one joint: after a repair the piping is brought back to test pressure and held for the full duration with no loss before it passes and the tag is completed. A second leak elsewhere would otherwise go unnoticed.
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A furnace with hot-surface ignition gets a call for heat. In what order does its control normally act?
- Inducer on, pressure switch closes, igniter warms, gas valve opens, flame proven
- Igniter warms, inducer on, gas valve opens, pressure switch closes, flame proven
- Inducer on, igniter warms, flame proven, gas valve opens, pressure switch closes
- Pressure switch closes, gas valve opens, inducer on, igniter warms, flame proven
Show the answer
A. Correct. The control starts the inducer, waits for the pressure switch to prove venting and prepurge, heats the igniter, opens the gas valve onto the glowing igniter, then must prove flame within seconds or close the valve.
Want ten more with every option explained? Free TSSA G3 practice questions: no account, no email, printable.
The TSSA G3 exam at a glance
How many questions are on the TSSA G3 exam?
The Gas Technician 3 (G3) is the first of Ontario's three gas technician certificates, G3, G2 and G1, issued by TSSA, the Technical Standards and Safety Authority. TSSA's Gas Technician policies (September 2025) set the G3 as nine modules and 180 suggested hours of training: safety, fasteners and tools, the properties of propane and natural gas, codes, acts and regulations, electricity, manuals and drawings, customer relations, piping and tubing, and gas appliances. TSSA's Certification Examination Preparation Guide (March 16, 2026) says every question is multiple choice and that Fuels exams, the G3 among them, need 75 percent to pass.
TSSA does not publish the G3 question count. Its preparation guide says its exams typically range from 50 to 165 questions depending on the certificate, with up to three and a half hours to write. Our timed mock exam is 100 questions in 180 minutes at 75 percent: that length is our choice for practice, not a TSSA figure. TSSA also publishes no per-module weights, although a candidate who fails gets a mastery report that breaks the score down by module.
The exam is open book. The guide lists, for the G2 and G3, the Technical Standards and Safety Act, 2000, all Fuels Regulations and their Code Adoption Documents, CSA B149.1 and CSA B149.2, with the B149.2S1 supplement optional. You bring your own copies, and they may carry highlighting, page dividers and tabs but no writing or notes. Since March 16, 2026 you apply through the TSSA Client Portal and write on a computer at a Prometric test centre, with results within 24 hours; TSSA describes in-person sittings only. TSSA's fee schedule from May 1, 2026 lists $255.50 for a challenge exam and $89 for other exams, and every re-write is billed again. After a fail you can re-write in 30 days.
The full TSSA G3 practice exam
Know your real G3 score before exam day.
550 practice questions for the Ontario G3 exam, 400 Standard and 150 Advanced, spread over TSSA's nine modules, with the reason for every option and every calculation worked in the explanation. Timed 100-question mock exams in 180 minutes, scored against TSSA's 75 percent pass mark, so you can see how you do on a full paper against the clock.
Also writing a Red Seal or 4th Class Power Engineering exam? All-Access covers G3 for $89, with all sixteen Red Seal trades and 4A and 4B included.
What the G3 exam covers
Nine modules, 180 hours of training.
TSSA's G3 is modules 1 to 9 of its gas technician training. TSSA does not publish how many exam questions come from each module, so our 550-question bank covers every module, and the counts below are what is in our bank, not on the exam. Each module links to five free questions on it.
- 1
Protect Self and Others · 38 in our bank
The rights and duties of workers, supervisors and employers and the safety bodies that apply to gas work, on-the-job safety and personal protective equipment, WHMIS and hazardous materials, and fire safety. Free Module 1 questions: safety →
- 2
Fasteners, Hand Tools and Power Tools · 28 in our bank
Fasteners and anchors, hand tools and their care, power tools and accessories, and the measuring, pressure, combustion and electrical test instruments a gas technician uses. Free Module 2 questions: fasteners and tools →
- 3
Properties, Characteristics, Safe Handling of Propane and Natural Gas · 70 in our bank
The make-up and physical properties of natural gas and propane, combustion and its products, the hazards of fuel gases and carbon monoxide, finding and responding to leaks, and handling propane containers. Free Module 3 questions: gas properties →
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Installation Codes, Acts and Regulations · 124 in our bank
The bodies that regulate gas work, the Technical Standards and Safety Act, 2000, O. Reg. 212/01 and 215/01, the Gaseous Fuels Code Adoption Document and its Ontario amendments, finding a requirement in B149.1, propane storage under B149.2 and O. Reg. 211/01, and working within the G3 certificate. Free Module 4 questions: codes, acts and regulations →
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Introduction to Electricity · 68 in our bank
Electrical hazards, voltage, current, resistance and power, series and parallel circuits, magnetism, direct and alternating current and transformers, and taking meter readings. Free Module 5 questions: electricity →
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Technical Manuals, Specifications, Schematics, Drawings and Graphs · 30 in our bank
Manufacturers' manuals and specifications, mechanical drawings, schematics and wiring diagrams, graphs, charts and tables, and units and conversion factors. Free Module 6 questions: manuals and drawings →
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Customer Relations · 14 in our bank
Communicating with customers, handling complaints and difficult situations, and preventing damage to the customer's property. Free Module 7 questions: customer relations →
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Introduction to Piping and Tubing Systems · 106 in our bank
Piping and tubing materials and where each may be used, joints, fittings and valves, location, support and protection, pipe sizing, pressure and leak tests, purging and activation, and the water piping that serves gas appliances. Free Module 8 questions: piping and tubing →
- 9
Introduction to Gas Appliances · 72 in our bank
Appliance types and ratings, burners and flames, pilots, ignition and flame sensing, controls and safeties, venting, draft and air supply, converting between natural gas and propane, and shutting down, cleaning and reactivating an appliance. Free Module 9 questions: gas appliances →
Where our questions come from
Every question, built from public sources.
TSSA gives its G3 curriculum to accredited training providers only, so the 50 objectives and 202 learning outcomes in our G3 bank are our own, written across TSSA's nine modules from public sources: the Technical Standards and Safety Act and the Ontario fuels regulations on e-Laws, TSSA's Code Adoption Documents and bulletins, manufacturers' installation manuals, and utility and safety-agency guides. Every question went through a separate, blind verification pass in which every number is recomputed: circuit values, piping loads, flammable limits and pressure conversions. Where a question rests on CSA B149.1 or B149.2, it explains the requirement in its own words; we never quote CSA code text, tables or clause wording. Ontario adopted the 2025 editions of both codes in June 2026, and the bank is written to them with Ontario's amendments; we found no TSSA notice saying when the exam itself moved to the new editions. Nothing is copied from textbooks, from training units or from recalled exam questions. For the exam format, fees and what you can bring into the room, read the TSSA G3 exam guide. Read how our questions are made.
Last reviewed against TSSA's Certification Examination Preparation Guide (March 16, 2026), its Gas Technician policies (September 2025), its fee schedule (May 1, 2026) and the Ontario regulations on e-Laws.
Why practice scores mislead
You can bring the code book and still miss the G3 questions.
The G3 is open book, but the book does not tell you where to look. Knowing that O. Reg. 212/01 deals with unsafe conditions does not tell you whether the gas is shut off before or after the distributor hears about it. Knowing Ohm's law does not stop you adding two coils in parallel as if they were in series. Much of the G3 is knowing which rule applies and the order the work is done in: what proves a repaired line tight, what a hot-surface control must prove before the gas valve opens. Our explanations give the reason behind every option, and our mock exams put 100 questions in front of you in 180 minutes, so you find out whether you can work through a full paper in time, not just whether you recognise the words.
How TicketPrep prepares you
Built like a study tool, not a quiz app.
All nine modules
Every one of TSSA's nine G3 modules, and every one of the 50 objectives we wrote for them, has questions, at Standard and Advanced levels.
Every answer explained
Why the right answer is right, and why each of the other three is wrong, with the regulation, the calculation or the working reason.
Timed mock exams
100 questions from all nine modules in 180 minutes, split by our own estimate. TSSA publishes neither the G3 length nor module weights, so this is our practice format.
Know your weak modules
Your score broken out by module, 1 to 9, against the 75 percent pass mark, so you know which module to drill next.
TSSA G3 exam questions
Before you start.
How many questions are on the TSSA G3 exam?
What can you bring into the G3 exam?
Which edition of B149.1 does the G3 exam use?
Is the G3 practice test free?
Can I challenge the G3 without taking a course?
What work can a G3 do?
Are these real TSSA G3 exam questions?
How is TicketPrep different from other G3 question banks?
Find out where you actually stand.
Five free questions, no account needed. See how you did as you go, then enter your email to read every explanation. About five minutes.
Then Exam Pass is $69 one-time for 120 days of access, not a subscription, with a 7-day money-back guarantee. Write the G3 and don't pass? You get 120 more days free. All-Access covers G3, 4A, 4B and all sixteen Red Seal trades for $89.
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