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Red Seal Program (with provincial and territorial apprenticeship authorities)

Red Seal Plumber Interprovincial Exam

The Red Seal Plumber exam is the interprovincial certification exam for the trade Ontario calls Plumber (306A). It has 125 multiple-choice questions drawn from seven major work activities in the Red Seal Occupational Standard, from DWV and water distribution to hydronic and specialized systems, and the Red Seal pass mark is 70%. You apply for and write it through your provincial or territorial apprenticeship authority.

Last checked against Red Seal Program (with provincial and territorial apprenticeship authorities) on .

Red Seal Plumber (306A) at a glance

Number of questions
125 multiple-choice questions source ↗
Pass mark
70% source ↗
Maximum time allowed
4 hours source ↗
Question format
Multiple choice, four options (A to D) with one correct answer source ↗
Largest exam area
MWA C, sewers, sewage treatment and DWV systems: 32 of 125 questions source ↗
National Occupational Classification
NOC 72300 source ↗
Current National Plumbing Code
National Plumbing Code of Canada 2025 (NRC); provinces and territories adopt editions on their own schedules source ↗
Ontario plumber apprenticeship
9,000 hours: 8,280 on the job and 720 in school; compulsory trade in Ontario source ↗
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What the Red Seal Plumber (306A) covers

AreaWeightWhat to know
A – Performs common occupational skills14 questionsSafety-related functions, tools and equipment, organizing work, and routine trade activities such as layout and trade calculations. Communication and mentoring is in the standard but carries no exam questions.
B – Prepares and assembles tube, tubing and pipe13 questionsPreparing tube, tubing and pipe (6 questions) and joining it by threading, soldering, brazing, solvent welding, mechanical and press methods (7 questions).
C – Sewers, sewage treatment and DWV systems32 questionsBuilding sewers (7), sewage treatment systems such as septic tanks and leaching beds (5), and interior drainage, waste and vent systems (20).
D – Water service and distribution24 questionsWater service (6), potable water distribution including backflow prevention and pressure control (12), and private water pressure systems such as wells and pumps (6).
E – Fixtures, appliances and water treatment systems17 questionsPlumbing fixtures and appliances, including water heaters (11), and water treatment systems such as softeners, filters and disinfection (6).
F – Low-pressure steam and hydronic systems16 questionsPiping and components for hydronic systems (9) and hydronic heating and cooling equipment (7). Low-pressure steam is not Common Core and carries no questions.
G – Specialized systems9 questionsProcess piping systems (5) and other specialized systems (4). Potable water fire protection is not Common Core and carries no questions.

How to get certified

  1. 1

    Register as an apprentice with your provincial or territorial authority

    Apprenticeship is run by each province and territory (for example Skilled Trades Ontario, SkilledTradesBC or Alberta Apprenticeship and Industry Training). Plumbing is a compulsory trade in Ontario, so you must hold a registered training agreement or certificate to do the work there.

  2. 2

    Complete your on-the-job hours and technical training

    Log your work-based hours with your employer and complete each level of in-school training. Ontario sets 9,000 hours for 306A, made up of 8,280 hours on the job and 720 hours in school. Other jurisdictions set their own requirements.

  3. 3

    Or apply as a trade qualifier / challenger

    Experienced workers who never registered as apprentices can usually apply to challenge the exam by documenting their trade experience. Each authority sets its own hour thresholds and evidence rules, so check before you apply.

  4. 4

    Get approved and book the exam

    Once your authority confirms you are eligible, it tells you how and where to write the interprovincial exam. Use the Red Seal Occupational Standard, the official exam breakdown and the self-assessment guide to plan your study.

  5. 5

    Write the exam

    Expect 125 multiple-choice questions and up to 4 hours. You need 70% to pass. A formula sheet and acronym list are provided with the exam. If you are unsuccessful, your authority sets the rules and waiting periods for a rewrite.

  6. 6

    Receive your certificate with the Red Seal endorsement

    Passing the interprovincial exam, along with meeting your jurisdiction's other requirements, leads to a certificate of qualification bearing the Red Seal endorsement, which is recognized across participating provinces and territories.

How to study

  • Study by the official weightings: DWV, sewers and sewage treatment (32 questions) and water service and distribution (24 questions) make up close to half of the exam.
  • Interior drainage, waste and vent systems alone carry 20 questions, so practise trap, venting, fitting and pipe-sizing rules until you can find them in the code quickly.
  • Practise navigating the plumbing code your exam is based on by Part, Section and Article, and tab the sizing tables you use most.
  • Work trade calculations every day with a basic calculator: grade and fall, 45° offsets, static pressure in kPa, tank volumes and hydronic heat transfer.
  • Take timed practice sets: 125 questions in 4 hours is just under 2 minutes per question, so skip and return to long calculations rather than stalling.

Frequently asked questions

How many questions are on the Red Seal Plumber exam?

The Red Seal Program lists 125 questions for this trade, all multiple choice. They are split across seven major work activities: 14 common occupational skills, 13 tube, tubing and pipe, 32 sewers, sewage treatment and DWV, 24 water service and distribution, 17 fixtures, appliances and water treatment, 16 hydronic systems and 9 specialized systems.

What score do I need to pass?

The Red Seal pass mark is 70%. On a 125-question exam that means at least 88 correct answers. Your provincial or territorial authority reports your result.

How long do I get to write it?

Red Seal states a maximum of 4 hours for its exams. Ask your apprenticeship authority about accommodations if you need them, because those are arranged locally.

Is 306A the same as the Red Seal Plumber trade?

306A is Ontario's code for the Plumber trade, which is part of the interprovincial Red Seal Program. In Ontario, Skilled Trades Ontario administers the certifying exam, and plumbing is a compulsory trade there. Other provinces use the Red Seal trade name.

Which plumbing code should I study?

The National Research Council publishes the National Plumbing Code of Canada; the newest edition is NPC 2025, which followed NPC 2020. Provinces adopt editions on their own schedules, and some, including Ontario, put their plumbing rules in the provincial building code. Ask your apprenticeship authority which code and edition your exam is based on before you buy a code book.

What kinds of questions are on the exam?

Red Seal says 15-25% of the questions test knowledge and recall, 60-70% test procedures and application, and 10-20% test critical thinking. There are no trick questions, but the wrong options are not always obvious, so read every choice.

Are steam and fire protection systems on the exam?

Low-pressure steam systems (task F-16) and potable water fire protection systems (task G-20) are marked as not Common Core in the official breakdown and carry zero questions. They are still part of the occupational standard, so you may need them for your provincial training.

Are these practice questions from the real exam?

No. VoltExam's questions are original items written to practise the topics in the official exam breakdown. They are not official Red Seal questions, and doing well on them does not guarantee a pass.

Free calculators for this exam

Official sources

Sources checked November 2, 2026. VoltExam is independent and not affiliated with Red Seal Program (with provincial and territorial apprenticeship authorities). Rules change: confirm details with the official source before your exam.