What 306A is
306A is the Ontario trade code for Plumber. The Certificate of Qualification is issued by Skilled Trades Ontario.
In general terms, the scope covers installing, maintaining and repairing piping systems that carry water, waste, and other fluids in residential, commercial and industrial buildings, to the applicable codes.
What compulsory means
No ticket, no tools. 306A is a compulsory trade in Ontario: to legally work in the trade you must hold the Certificate of Qualification or be a registered apprentice in it.
Hiring uncertified labour for 306A work exposes the contractor too, not just the worker doing it.
The way in
The main route in is a registered apprenticeship through Skilled Trades Ontario. Hour and competency requirements are published there, so check their site for the current standard rather than relying on a secondhand number.
Experienced workers from elsewhere can apply to Skilled Trades Ontario to have their credentials or experience assessed.
The Red Seal exam
Plumber is a Red Seal trade. Passing the interprovincial Red Seal exam adds the Red Seal endorsement, which lets the holder work across provinces without re-examination.
The exam is multiple-choice, built from the Red Seal Occupational Standard. Pass mark, question count, breakdown, sample questions and counselling sheets are published on red-seal.ca.
Every ticket and cert, in one place
Blue Crane keeps every ticket, cert and renewal for the crew in one place, filed to the worksite, with warnings before anything lapses. Free for 30 days, no card.
FAQ
Can I do plumbing work in Ontario without a 306A?
Not in the trade's scope. 306A is a compulsory trade, so you must hold the Certificate of Qualification or be a registered apprentice to legally do the work. The trade's scope and the requirements are published by Skilled Trades Ontario.
How do I get a 306A if I trained outside Ontario?
Apply to Skilled Trades Ontario to have your credentials or experience assessed. If your existing certification qualifies, they set out the route to the Ontario certificate; the requirements are published on their site.
Does my 306A work outside Ontario?
The 306A itself is an Ontario credential. Passing the interprovincial Red Seal exam adds the Red Seal endorsement, which is recognized across provinces and territories without re-examination.
Related: read the training hub, or the pages for 433A and 309A.