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How to Become a Gas Technician in Ontario
Ontario's TSSA gas technician ladder: G3 entry certification, the G2 upgrade, training hours, exam format, costs, and contractor registration.
Applies in: Ontario
The path in one paragraph
Ontario licences gas technicians through the Technical Standards and Safety Authority (TSSA) on a three-rung ladder: G3 (entry, supervised), G2 (independent work up to 400,000 BTUH, the credential employers actually want), and G1 (no size limit, commercial and industrial). You get to G3 through a TSSA-accredited school program (about 213 hours) or by challenging the exam, log 4,000 supervised hours as a certified G3, then upgrade to G2 with a second course (about 420 hours) and the TSSA G2 exam. Plan on two to three years from zero to G2, earning a wage through the supervised middle years, and add a TSSA contractor registration if you ever want to run your own shop.
First: the licence structure matters
Get the ladder right before you plan: beginners consistently misread which rung they can work from:
- G3, Gas Technician 3. The entry ticket. You may do a defined list of tasks under the general supervision of a G2 or G1 holder (readily available, not necessarily on site), once your skills are demonstrated and signed off. No independent work, no unsupervised side jobs. Think of it as a licence to learn and log hours.
- G2, Gas Technician 2. The working credential. Installation, maintenance, and testing of gas lines, meters, regulators, and appliances up to 400,000 BTUH, independently. This is the card Ontario HVAC and heating employers write into job postings.
- G1, Gas Technician 1. The ceiling remover. Large commercial and industrial systems over 400,000 BTUH. Requires two years as a G2 plus 500 hours on oversized systems under direct G1 supervision.
Two things that trip people up. First, gas technician certification is not an apprenticeship and is not a Red Seal trade. It runs on TSSA's own track, separate from Skilled Trades Ontario. Second, Ontario law is blunt: under the Technical Standards and Safety Act and O. Reg. 215/01, anyone doing regulated fuel work must be certified, and the business must hold an active TSSA contractor registration (fines up to $50,000 for individuals, $100,000 for corporations per offence). Homeowners are told to demand both numbers before a truck rolls.
G2 vs G3 side by side: what each rung actually lets you do
This is the comparison beginners ask for most, and the shorthand most guides repeat ("G3 = supervised, G2 = independent") hides the details that decide what your day looks like. The scope rules below come straight from O. Reg. 215/01, sections 21 and 22:
| G3 | G2 | |
|---|---|---|
| Works independently? | No: supervised work only | Yes |
| Size cap | 400,000 Btuh | 400,000 Btuh (the same) |
| Legal scope | A defined list only (O. Reg. 215/01 s. 22(1)): gas piping/tubing under 2½″ to the appliance, reactivating a previously installed or converted appliance, cleaning and lubricating, vent connectors/venting/draft controls | Everything the regulation's G.2 scope lists (s. 21(1)): install, inspect, alter, purge, activate, repair, service, or remove a natural gas or propane appliance up to 400,000 Btuh, plus the G.1-scope piping functions in s. 20(2) |
| Type of supervision | "General supervision": a G1, G2, or DA holder who is readily available, not necessarily standing over the work. To touch the defined list you must first show you can do the work and have it signed off on the director's form | None required; a G2 may also work inside a G1's scope under a G1's direct supervision |
| Hardest line | No initial activation of a new or newly converted appliance: s. 22(2) is explicit, so the first-fire call on a fresh install is never the G3's job | No such restriction at this size band |
| What changes in practice | A G3 with a completed sign-off package is useful on a truck doing service calls, venting, and reactivations; a G3 without one is learning and logging | The G2 is the deployable unit: on your own ticket, customer-facing, revenue-generating |
Two honest caveats people miss. First, the G3's "defined list" reads narrow but covers a lot of real residential service work (venting, reactivations, small piping), which is why contractors hire G3s and keep them busy. Second, the supervision requirement is not casual: the supervising certificate holder signs your skill documentation, and those signed hours are the same hours that earn your G2, so who supervises you matters as much as what you do.
The exam rules and certificate mechanics schools skim over
The training programs teach to the exam but rarely walk you through the exam's own rulebook. These are the rules from TSSA's certification policies and O. Reg. 215/01:
- Pass mark: 75%. On the written exam and on the practical evaluation. Not a curve: seventy-five or you rewrite.
- Fail, and you wait 30 days before writing again. You get a results breakdown showing which topics sank you, so use it.
- Three successive failures ends the shortcut: you must complete an accredited program again before writing a fourth time (O. Reg. 215/01 s. 5(4)). This is the same rule for challenge-route and school-route writers.
- A passing grade is valid for 12 months. Write the exam within one year of completing training, and if you challenged, complete the practical evaluation within one year of passing the written, or the result lapses.
- Exam day mechanics: government-issued photo ID at the invigilator's desk, no dictionaries or translators, and the invigilator must be someone other than your program instructor. Schools add attendance gates (80% minimum is the common rule) before they will even book you.
- Renewal is not automatic. Your certificate carries an expiry date: working past it without renewing is unlawful (s. 4(1)). Renew before expiry or within one year after, and you must complete an upgrading course by the director's deadline. Let it lapse a year or more and the application is treated as brand new: the full path, start to finish.
Step 1: Pick a TSSA-accredited G3 program
Training for any level must be TSSA-approved. TSSA's certification policies say so explicitly, and only accredited programs make you eligible to write the TSSA exams. G3 programs run roughly 213 hours (about six to twelve weeks full-time, longer part-time) covering safety, fuel properties, the utilization codes, basic electricity, piping and tubing, and gas appliances. Schools publish their own eligibility gates: St. Lawrence College, for example, requires 75% in each module and 80% in-person attendance before you can write the TSSA G3 exam.
Admission is straightforward: an Ontario secondary school diploma or equivalent, or mature-student status (18+) with a qualifying entrance assessment. Verify any school against TSSA's accredited training-provider list before you enrol: an unaccredited program burns your tuition and your exam eligibility.
Step 2: Write the TSSA G3 exam
The exam is entirely multiple choice: sector-knowledge questions plus technical questions for the level, running 50 to 165 questions with up to 3.5 hours on the clock. Pass, and you hold the G3 certificate. If you took the challenge route instead of school, one more gate applies: a TSSA practical evaluation, billed around $135 per hour, completed within one year of passing the written exam.
Costs for reference: G3 programs at accredited schools typically run a few thousand dollars (one Ontario school publishes $3,900 including modules, codebooks, and the exam fee: use it as a reference point, not a market price). Challenging the exam directly costs on the order of $200 (application plus exam fees per the TSSA fee breakdown providers publish), plus the practical evaluation. Confirm current fees on tssa.org before you book.
Step 3: Work supervised and log 4,000 hours
The G3 years are where most people actually build the career. Get hired by a mechanical contractor, heating company, or appliance service firm, and work under a G2 or G1 holder who signs your hours. Those 4,000 hours are the documented price of admission to the G2, and TSSA is strict about what counts: hours must be accumulated after your certificate was issued, verified by your supervising certificate holder and your employer. Uncertified prior experience does not count.
Use this period well. The G2 exam tests advanced piping, controls, regulators, venting, and forced-air and hydronic systems: the things a good service employer has you touching daily. Our HVAC guide covers the 313A apprenticeship that pairs naturally with the gas licence; many technicians stack both.
Step 4: Upgrade to G2
With 4,000 documented G3 hours, you have two routes: the G2 course (about 420 hours at an accredited school) or a direct challenge of the TSSA G2 exam plus practical evaluation. The exam and the supervision rules mirror the G3 process: multiple choice, technical and sector sections. Passing makes you independently deployable: gas lines, meters, regulators, and appliances up to 400,000 BTUH, on your own ticket.
G2 is also the rung where the pay meaningfully changes. Certified G2 technicians are the hiring unit in Ontario's heating service market; G3s, by law, are somebody's apprentice-equivalent.
Step 5: G1, and the business option
G1 is optional for most residential and light-commercial careers. Pursue it only if large commercial or industrial work is where you want to be: another 4,000 hours as a G2, with 500 hours on systems over 400,000 BTUH under direct G1 supervision.
The business side needs its own step because the licence and the registration are different things. Your G2 is your personal credential. To sell gas work to customers, the business needs a TSSA contractor registration, registered with TSSA and renewed every year. Enforcement is real: in December 2025 TSSA fined an Ontario contractor $10,000 (plus a victim surcharge) for fuel-safety violations including an expired contractor registration. Layer on liability insurance, a business name or incorporation, and GST/HST registration past $30,000 in annual revenue. Our sole proprietorship guide covers the registration mechanics.
Where to train: gas technician schools in Ontario
Our directory of gas technician training programs in Ontario lists TSSA-recognized providers and pre-apprenticeship programs, every one verified.
Related guides
- How to become an HVAC apprentice in Ontario — the 313A trade certificate routinely listed alongside a G2 in the same job posting, the Red Seal-endorsed route behind the pairing.
- How to become a gasfitter apprentice in Alberta (Class A & B) — the Alberta regime: compulsory AIT apprenticeship with the Class A/B split at 400,000 BTU, versus Ontario's TSSA certificate route.
What the G3 path costs
| G3 program at one accredited Ontario school (includes course modules, codebooks, and the exam fee) | $3,900 |
|---|---|
| Challenge route: application fee | $100 |
| Challenge route: exam fee | $100 |
| Practical evaluation (challenge route) | About $135 per hour |
Questions people ask
What is the difference between G3, G2, and G1 gas licences in Ontario?
They are the three levels of gas technician certification issued by the TSSA. G3 is the entry level: you may work only on a defined list of tasks from O. Reg. 215/01 s. 22(1) — small gas piping/tubing under 2½ inches, reactivating previously installed or converted appliances, cleaning and lubricating, and venting/vent connectors/draft controls — under the general supervision of a G2, G1, or DA holder (readily available, not necessarily on site), and only after your essential skills are demonstrated and signed off. A G3 may never do the initial activation of a new or newly converted appliance (s. 22(2)). G2 lets you work independently on gas lines, meters, regulators, and appliances up to 400,000 BTUH — this is the standard credential most Ontario HVAC and heating employers expect. G1 removes the size ceiling entirely and covers large commercial and industrial systems. You start at G3 and climb with training plus documented hours.
Can a G3 gas technician work without a supervisor on site?
The regulation does not require the supervisor to stand over the work — the legal term for the G3's listed tasks is 'general supervision' (O. Reg. 215/01 s. 1): a G1, G2, or DA holder who is readily available to assist, on site or not. Two conditions: you may only do the defined task list in s. 22(1) (small piping, reactivations, cleaning, venting), and only after the supervising certificate holder has documented your essential skills on the director's form. For anything outside that list, a G3 works under the direct supervision of a G1, G2, or DA holder — on site, in close proximity (s. 22(4)). If you're hired as a G3, ask your employer up front who your supervising certificate holder is and when your sign-off happens.
What happens if I let my gas technician certificate expire?
Working past the expiry date without renewing is unlawful — O. Reg. 215/01 s. 4(1). You can renew before expiry or within one year after, but a renewal requires you to complete an upgrading course by the director's deadline. If the certificate has been expired a year or more, the application is treated as brand new — the full path applies again. And remember the exam side has its own clock: a passing grade is valid for 12 months, so the written exam, practical evaluation, and training must stack inside that window.
How long does it take to become a G2 gas technician in Ontario?
Plan on two to three years from zero. The G3 course at a TSSA-accredited school runs about 213 hours, after which you write the TSSA G3 exam. You then need 4,000 documented hours of field experience working as a certified G3 under supervision — prior uncertified experience does not count — before you can challenge or train for the G2. The G2 course itself is about 420 hours of training, and the TSSA G2 exam follows. G2 holders eyeing G1 need another 4,000 hours as a G2, including at least 500 hours on systems over 400,000 BTUH under direct G1 supervision.
Do I need to attend a TSSA-approved school, or can I challenge the exam?
Both routes exist, but the challenge route is narrow. TSSA's certification policies let someone with no certification challenge the G3 exam directly, and a certified G3 with 4,000 documented hours can challenge the G2 — but you still must pass a TSSA practical evaluation within one year of the written exam, and the documented hours must be verified by your supervising certificate holder and employer. Most beginners are better served by a TSSA-accredited school: the structured course covers the code modules the exam tests, and schools handle the exam booking. Check that any school you consider is on TSSA's accredited list before you pay.
How much does gas technician training cost in Ontario?
G3 programs at TSSA-accredited schools typically run a few thousand dollars — one accredited Ontario school publishes $3,900 including course modules, codebooks, and the exam fee, which is a useful reference point rather than a market price. Challenging the exam directly costs on the order of $200 combined (a $100 application fee plus a $100 exam fee, per the TSSA fee breakdown training providers publish), plus roughly $135 per hour for the mandatory practical evaluation. The G2 course costs more than G3 — budget several thousand more — and you'll be earning a wage through the supervised G3 period in between. Verify the current fee schedule on tssa.org before you book, since fees change.
What does the TSSA gas technician exam look like?
All multiple choice, with a sector-knowledge section and a technical section for the level you are challenging. Expect 50 to 165 questions depending on the level, with up to 3.5 hours to write. Schools add their own gates: St. Lawrence College, for example, requires at least 75% in each module and 80% in-person attendance before you are eligible to write the TSSA exam. If you challenge rather than attend school, remember the practical evaluation must be completed within one year of passing the written exam, or the challenge approval lapses.
Can a G3 gas technician work on their own or take side jobs?
No. A G3 certificate legally requires working under the direct supervision of a G2 or G1 holder — unsupervised G3 work is not permitted, including side jobs for friends and family. On top of that, the business performing the work must hold a valid TSSA contractor registration. Supervised-employment is the honest shape of the G3 years: you are building the documented 4,000 hours that unlock the G2, and a good employer will sign those hours properly.
What do I need to start my own gas fitting business in Ontario?
Three layers. First, your personal credential: practically a G2 (the G3 can't work unsupervised). Second, TSSA contractor registration for the business — every fuels contractor must register with TSSA and renew every year; operating with an expired registration draws real penalties (a 2025 TSSA enforcement case fined a contractor $10,000 for fuel-safety violations including an expired registration). Third, the ordinary business machinery: a business name or incorporation, liability insurance, and GST/HST registration once you cross $30,000 in annual revenue. Our sole proprietorship guide walks through the BN and GST/HST mechanics.
Is gas technician a Red Seal trade?
No. Gas technician certification is issued by the TSSA (and its counterparts in other provinces), not through the apprenticeship system, so there is no Red Seal endorsement to earn. The pairing that matters: many gas technicians also hold a Skilled Trades Ontario trade certificate — 313A refrigeration and air conditioning mechanic is Red Seal-endorsed and routinely listed alongside a G2 in the same job posting. If national portability matters to you, the Red Seal route runs through the trade certificate, not the gas licence.
Does my Ontario gas technician certificate work in other provinces?
No — not automatically. Gas technician certificates are provincial: a TSSA certificate authorises you in Ontario. Other provinces have their own safety authorities and certificate structures (for example, Technical Safety BC on the west coast). Some offer recognition of out-of-province credentials, but the process, scope, and conditions vary. If a move is likely, talk to the destination province's safety authority before you count on your Ontario ticket.
Is certification actually mandatory, or can I learn on the job?
Certification is mandatory. In Ontario, anyone working on gas-fired equipment — residential, commercial, or industrial — must be certified by the TSSA, under the Technical Standards and Safety Act and O. Reg. 215/01 (Fuel Industry Certificates). The business layer is equally non-negotiable: only contractors with active TSSA registration are legally authorised to perform regulated fuel work. Homeowners are told to ask for both numbers for a reason — fines run up to $50,000 for individuals and $100,000 for corporations per offence.
Sources
- TSSA, Fuels Industry Professional page (challenge approval rules, practical evaluation timing, certificate renewal process)
- TSSA, Contractor Registration and Certification (fuels contractor registration requirement, technicians must be trained and certified)
- TSSA news release, December 5, 2025 (contractor fined $10,000 for fuel-safety violations including expired registration; annual renewal requirement)
- St. Lawrence College, Gas Technician program page (G3 — 213 hours, 75% per module and 80% attendance for TSSA exam eligibility; G2: 420 hours) —
- Skilled Trades College of Canada, Gas Technician 3 FAQ (G3/G2/G1 scopes; supervision requirement; OSSD or mature-student admission; $3,900 tuition reference)
- Herzing College blog, "Becoming a Certified Gas Technician — 6 Things to Know About the TSSA Exams" (G3/G2/G1 scopes, 400,000 BTUH limits, exam format: 50–165 multiple-choice questions, up to 3.5 hours; TSSA accreditation requirement) —
- Get a Trade, Gas Technician 3 & 2 Combined course outline (G3/G2 unit breakdown)
- TSSA Gas Technician / Oil Burner Technician Policies and Procedures via docplayer (G3/G2 challenge prerequisites — 4,000 hours as G3, practical evaluation within one year, documented/verified experience; G1: 4,000 hours as G2 plus 500 hours on >400,000 Btuh systems; 75% pass mark, passing grade valid 12 months) —
- Ontario e-Laws, O. Reg. 215/01 — Fuel Industry Certificates (consolidation Jan 1, 2022; read 2026-10-20): s. 21 — G.2 scope (independent, ≤400,000 Btuh); s. 22 — G.3 scope (defined task list under general supervision, skill sign-off, no initial activation of new/converted appliance); s. 4 — expiry and renewal (lapse >1 year = new application, upgrading course on renewal); s. 5 — three successive failures require program re-completion; s. 1 — general vs direct supervision definitions —
- Herzing College blog, TSSA gas technician exam pages (exam format 50–165 questions / up to 3.5 hours, 75% pass, 30-day rewrite wait, three-fail rule, exam within 1 year of training, 80% attendance, photo ID, results breakdown) — TSSA gas technician exam pages and TSSA gas technician exam pages