During the recent blackout in the north east, buildings in my area (Staten Island, NY), with multi phase supply lines, had power on specific phase legs of the incoming power. Most buildings are supplied power in this way
If you have multi phase, you should have an electrician run separate circuits to your server room, making sure the circuits are connected to different phase legs of you distribution box ( circuit breaker panel). During the next blackout you may have power on some circuits.
