I am talking about a room that surrounded by 2 inches of concrete or other equivelant and probably a 2 hour door. It may not be that practical vs just putting the service equipment in an outdoor location if that becomes the requirement. But I would sure think it should be an option if the requirement requires the service equipment outside the building. Is no different than the fact we can currently encase service conductor raceways in concrete and consider them outside building. It probably will create other headaches like what penetrations are acceptable to leave the vault to supply the structure?