Provinces / Ontario

Ontario

Jurisdiction note

Ontario operating engineer and ski lift mechanic certificates are issued by the Technical Standards and Safety Authority. Refrigeration and Air Conditioning Systems Mechanic (313A) and Welder (456A) certifying exams are administered by Skilled Trades Ontario.

Guides for Ontario

Checked facts are on the guide. Anything still open is labelled TO-CONFIRM or TODO.

ON4th Class Power EngineerTwo multiple-choice papers, Part A and Part B. The current published format is 100 questions and 3 hours on each paper, with 65% required on each paper. The province decides whether you may write, what you pay, and how you book.
ON3rd Class Power EngineerFour multiple-choice papers: 3A1, 3A2, 3B1, and 3B2. SOPEEC, Alberta, and British Columbia publish 100 questions, 3 hours, and 65% on each paper. Ontario's TSSA 3rd Class question count and sitting length are still TODO. You already need a 4th class footing before this exam in the provinces reviewed here.
ONSki Lift MechanicA provincial certificate for passenger ropeways in Ontario. The February 2026 policies require a TSSA exam at 70%, and you bring your own CSA Z98. Question count, sitting length, and the current exam fee were not published in a form this guide could quote.
ON313A RefrigerationThe national exam has 125 multiple-choice questions and a 70% pass mark. You get four hours. Provinces schedule it, set the fee, and issue the certificate. In Ontario the trade is compulsory.
ONRed Seal WelderThe national welder exam has 125 multiple-choice questions, four hours, and a 70% pass mark. Welding processes are 54 of those questions. There is no Hesson practice app for this trade yet, so the page collects a waitlist.
ON309A Construction ElectricianThe Construction Electrician Red Seal exam has 100 multiple-choice questions, a 4-hour limit, and a 70% pass mark. Fees and rewrite rules are provincial.
ON306A PlumberThe Plumber Red Seal exam has 125 multiple-choice questions, a 4-hour limit, and a 70% pass mark. Fees and rewrite rules are provincial.
ON433A Industrial Mechanic (Millwright)The Industrial Mechanic (Millwright) Red Seal exam has 135 multiple-choice questions, a 4-hour limit, and a 70% pass mark. Fees and rewrite rules are provincial.
ON421A Heavy Duty Equipment TechnicianThe Heavy Duty Equipment Technician Red Seal exam has 135 multiple-choice questions, a 4-hour limit, and a 70% pass mark. Fees and rewrite rules are provincial.
ONG3 Gas Technician 3TSSA's Fuels passing grade for Gas Technician 3 is 75%. The written exam is multiple choice, open book, and up to 3.5 hours. TSSA does not publish a fixed question count.
ONG2 Gas Technician 2TSSA's Fuels passing grade for Gas Technician 2 is 75%. The written exam is multiple choice, open book, and up to 3.5 hours. TSSA does not publish a fixed question count.