In neighbouring Manitoba there's a carve out for locomotive engineers, power engineers, and certain types of electrical work, as long as they're certified by their respective bodies and not pretending to be a different kind of engineer. Didn't see anything in the Ontario act but I wouldn't be surprised if it were there somewhere.

edit: https://web2.gov.mb.ca/laws/statutes/ccsm/e120e.php#66 section J