Line feeds both STR and RU simultaneously, they switch the motor from wye to delta. The good news is all the cars in the store (4)are now getting soft starts. As for the fire system, the only reason that I can figure that the system didn't trip was that this particular unit was directly under the outside vent.(which is very large due to multiple power units in the room)I have been a volunteer firefighter for 20 years and this one is sure strange. I think the lid on the tank probably stopped the oil from catching fire by excluding the oxygen, I'm sure it had reached its ignition temp!