Medical gases are oxygen, nitrogen oxide, and oxygen. They are piped to many rooms in a hospital. Gauges read their pressures and go into alarm when not within spec. I never mentioned "critical systems" but of coarse the most important purpose of the generator in a hospital is to provide critical and emergency power when called upon to do so. Generator annunciator wiring is not circuit wiring. Both the med-gas and generator wires I am describing are for status indicating only. The conductors feeding the gas valves I mentioned before are actually fed separately.