Can PVC conduit be run through garage/house firewall?
That should be fine as long as it's Schedule 80 pipe (thanks, Ed Beal). A garage &quot;firewall&quot; isn't usually considered a fire-rated situation like you'd find in a multi-family dwelling. It's just a minor safety measure. Therefore, per my understanding, you wouldn't need a fire-rated penetration. You'd just need to seal it as you describe. Ask your local inspection office (even if you're not getting inspected) to be sure what they'd ask for.
Consider slipping a trim ring onto the pipe to cover the ugly red caulk if your garage is finished.