Generators are put in dedicated rooms all the time for industrial applications. I'd love to have the unit from Verizon Granada Hills C.O. - 750KW Continuous, 1MW surge - and you need that when you're starting two 50-ton AC units and several 5 to 10-Ton ones, and all the Phone Switch battery chargers. The phone switch is a huge computer, they don't like working when they get hot.
An Architect, Engineer, and special permits required. You have to make a separate sealed room in the building with provisions for taking the exhaust out the roof to a proper stack, away from all windows and air intakes. Large fixed vent louvers in the wall low and high, and forced ventilation when the engine is running. Remote fuel tank buried or pad-mount outside - only a small Day Tank allowed in the room. Fire sprinklers. Extinguishers. Fire rated doors, walls, ceiling into the rest of the building
And a proper transfer switch, with a way to monitor the Utility line to see if it's back yet. If you just transfer the whole house that's fine, but you still have to tap off a separate 15A breaker to be able to monitor utility power.
You could do the same thing on a smaller scale at home, but you'd still better plan it all out properly first.
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