I think a cooling tower fan (which based on the HP rating is in a very large tower) would not generally qualify as having the possibility of injury to persons, as defined in that reference. That would tend to apply to conveyors, mixers, process machinery and the like, where sudden restarting could injure someone. It is reasonably assumed (yeah, we know what happens when one assumes) that when the tower is being worked on, LOTO would be applied.
Since this is a dual-speed application (maybe- I really think it's a wye-delta start arrangement) though, a manual reset overload would probably have prevented this breakdown.
UL has a standard for overload protection for fan motors (I think it's #508) which specifies that auto-reset overloads shall not be used where a fan is unattended (like a tower) or where the operator may not detect a locked-rotor or failure to start condition.
So, the upshot here is that the overloads should have been manual-reset to begin with. Drillman's doing the right thing.
Im my field, the only overloads set for auto reset are for lamp exhaust and cooling fans. Projector and transport motors have fuse/breaker or manual reset protection.
Drillman megger'd the motor..are you sure it's not locked up? Bad bearings, etc.?
In any event, be very careful when testing. 480 and a motor of that size can bite pretty hard!
