Matthew Olearczyk, a program manager with the Electric Power Research Institute, explains that typically a squirrel will cause a blackout by scampering across electrical equipment and touching simultaneously both an energized component, like one of the cylindrical transformers at the top of a utility pole, and a grounded piece of equipment. The squirrel completes the circuit, generating an arc. There is an instantaneous flash of blue light. At its center is the squirrel, combusting.