If case precedence simply defines a safe is as a locking metal box then even one of those flimsy Snap-on cabinet metal lock boxes could be defined as a safe. That doesn't seem right to me.
Go look it it up the containers in the case were school lockers a dude put padlocks on.
Under Section 40 of the Criminal Code, which deals with the defence of dwellings, "everyone who is in possession of a dwelling house is justified in using as much force as necessary, to prevent any person from forcibly breaking into or entering the dwelling house without lawful authority."