Truth is in the Details ™

The Case of the Radiant Rodent

Synopsis:
Penny wise and pound foolish business decisions sometimes come back to bite you.

Background:
A squirrel with walnut-in-mouth was climbing on a 20 MVA (like 20 megawatt) municipal substation transformer when it shorted the 12,470-volt output creating a massive arc. Protective equipment for the substation failed to open the circuit and the arcing was sustained for the better part of a minute until an employee ran into the building and cut the power.

Assignment:
TI was requested to determine the specific physical factors that resulted in substation damage since the utility had coverage for fire but had elected not to carry coverage for electrical equipment breakdown.

 
Analysis:
TI’s on-site interviews learned that a nearby resident had heard the loud noise of the initial arc and upon looking saw the sustained arcing in process. Cell phone at hand, the neighbor caught the balance of the arcing event on video. TI carefully inspected the loss scene and noted that there was no material within the loss area that was capable of supporting combustion. The dense black smoke was primarily the result of thick insulation materials on high voltage wires decomposing within the arc. The cell phone video was notable in that it showed the employee running into the building and the illumination from the arc abruptly ceasing when the employee cut power to the transformer. With the power cut, no ‘fire’ remained. TI precisely described, compared and contrasted the differences in physical factors at work in an electric arc as compared to combustion in a fire and, after so doing, concluded that no damage was done by actual fire in the arcing incident. Unfortunately for the owner, the insurance it had selected provided coverage only for fire, not electric arcing.

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