Hi, 

I cant figure out a way to get the owner of a placed item such as a furnace when using OnEntitySpawned. Can someone help?

Have you tried casting it to BaseEntity, then using the field "BaseEntity.OwnerID"?

Off the top of my head, the game may be setting the OwnerID right after spawning it. If so, you would have to perform the check in a NextTick callback, or use a different hook that is called later, such as OnEntityBuilt.