I think you will find that those circuits use isolation transformers and have no path to earth normally -- if you touch active and normal building earth there i

I think you will find that those circuits use isolation transformers and have no path to earth normally -- if you touch active and normal building earth there is no circuit. At to amperage ratings, don't you just mean that they have a 10x safety factor? Probably using current limiting supplies that can handle a short circuit. Fire circuits (and the feed from the main panel) should use fire rated cabling -- generally mineral insulated copper sheathed cables. Most of the standards (NFPA 75/76) are moving away from being prescriptive to being risk or performance based though, so it is possible they used normal conduit if the overall risk was small. Incidentally, hospitals also make extensive use of isolation transformers for wet areas (like emergency / ICU), to provide a local point for resetting breakers (electronically), identifying which point is tripping, etc, see IEEE 602-2007. Much better filtering for medical equipment too. You also tend to see positive retention plugs (in the US, green dot UL 817).