The basic rule is that OHS requirements are based on the site of the work, not residence. Site issues can get complicated, though, if you’re in a federally regulated industry but work at a site governed by provincial OHS law.
Following the OHS laws isn’t a problem since requirements for workers don’t vary much by jurisdiction. Take comfort in knowing that it’s up to your employer and/or prime contractor if you work on construction sites where workers of multiple employers work, to know and comply with the local OHS requirements.
Generally, workers comp claims must be filed in and subject to the laws of the jurisdiction where the worksite is located. However, things can get tricky, for example, if the injury occurs away from the site in another province, e.g., where a trucker working for an Ontario employer gets into an accident in Manitoba. The good news is that you should be able to approach the Worker Advisor or workers’ comp agency of the jurisdiction for guidance in filing your claim.