Trying for physical security on a larger job site is pretty much impossible. They open the right box the hard way first and then they have torches or power saws or whatever they need. If it's too heavy, there are cranes, loaders, and forklifts available. Usually a couple of trucks so they don't have to risk anything of their own. a dedicated crook will find a way. As much as you can just don't leave anything on a job site and hope they don't follow you home.
