This is happening in real time. I have a 600 volt 225amp distribution breaker tripped however the handle is physically still in the closed position. I'm the only one in the building and there's no way I can get the dead front of the switchboard by myself. Any idea what would cause this? It's ultimately feeds 3 10 amp in ceiling unit heaters for a mechanical room.The reason I'm asking is am a little more than paranoid about the selective coordination in this building and I have no idea what the load is at the main breaker. It wouldn't be the first time the main breaker tripped out of coordination. This circuit has also been mislabeled in the building print. I have not checked any of the associated circuits for issues as of yet... Obviously LOL

I hope that turned out okay.

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Thanks.All the equipment is under loto for now and I have checked the breaker to be sure its not hot.This is a hospital and since its a normal power and not a emergency power panel so im leaving it as it stands until tomorrow when the rest of the crew gets here.Ive seen this issue many times before in 120/208 panels over the years and its usually an easy fix but this is the first time i have seen it in a big breaker.Ill let you now what happens.