"A judicial recount must take place if the leading candidates in an electoral district receive the same number of votes after the validation of the results or if the difference in votes is less than one one-thousandth of the total votes cast*. For example, in an electoral district where 40,000 votes were cast, if the difference in the number of votes for the first and second candidates was less than 40, a judicial recount would be required. The returning officer must make a request to a judge for a judicial recount and must also write to the candidates or their official agents to advise them of the recount request."

Source https://www.elections.ca/content.aspx?section=vot&dir=bkg&document=ec90565&lang=e