Failure Analysis of a Refrigerator’s Double-Throw Switch Implicated in a Kitchen Fire

A residential fire occurred, appearing to originate in the kitchen of the home. The region of greatest damage was near the refrigerator. A double-throw switch in the refrigerator was found to be heavily damaged and alleged to have been the initiating component by one expert. Recreation testing by that expert, meant to test and disprove a competing hypothesis of the fire origin, instead showed that similar features found on the subject double-throw switch related to interdiffusion of the silver contact and brass base materials and migration of the contact were likely generated by an externally sourced fire while the switch remained powered. As a result, the double-throw switch was not the cause of the fire origin.