the structural damage might have been able to bring the building down, some engineers said. But that would not explain steel members in the debris pile that appear to have been partly evaporated in extraordinarily high temperatures, Dr. Barnett said. " Comment number 84. "A sustained fire from burning diesel fuel would have been sufficient to raise the temperature of the steel columns on the lower floors to the point where they could no longer sustain the weight of the entire structure above them." You think it was diesel Fuel? The following is from NIST's website. "Q: Did fuel oil systems in WTC 7 contribute to its collapse? A: No. The building had three separate emergency power systems, all of which ran on diesel fuel. The worst-case scenarios associated with fires being fed by ruptured fuel lines -- or from fuel stored in day tanks on the lower floors -- could not have been sustained long enough, could not have generated sufficient heat to weaken critical interior columns, and/or would have produced large amounts of visible smoke from the lower floors, which were not observed." Comment number 85. There are many possible explanations for some of the steel being vaporized. One of the most likely IMO is the possibility that during the collapse, live medium and high voltage electrical feeders short circuited to ground through the collapsing steel on top of them before protective overcurrent circuits upstream de-energized them. This is entirely plausible in such a failure scenario and while