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Dish Washer Fire

Upon returning from an overnight trip a family of four arrived back home to find water streaming out of their house. Inside they found there had been a kitchen fire and the water was coming from a dishwasher hose that had sprung a leak. The fire had self-extinguished, most likely due to a lack of oxygen.


Kitchen - Upper View.

Kitchen - Lower View.

After settling with the homeowner for the fire damage, the homeowner's insurance company filed a subrogation claim against the manufacturer of the dishwasher. Chemaxx and Dr. Fox were hired by the legal team defending the dishwasher company and the retailer that sold the dishwasher. The general scope of Dr. Fox's assignment was to review the different reports and expert opinions and analyze and comment on those opinions in the context of NFPA 921, the Guide for Fire & Explosion Investigation.

The claimant's hypothesis for the cause of the fire was that some mechanical damage was done to the incoming 120v wire insulation inside the dishwasher early in the life of the dishwasher either during shipment or installation. Then, some 11 years later, after dust, smog or other non-specific pollution accumulated on the wire that then led to an arc that set fire to the non-specific pollution which then set fire to the flame resistant wire insulation which then set fire to an unknown fuel which then set fire to the inside of dishwasher.

One of the electrical experts for the Claimant specifically referred to "dust bunnies" to help explain the above dust-smog-pollution scenario. For brevity, the Claimant's scenario was subsequently referred to as the "Dust Bunny Hypothesis." It is clear that the Dust Bunnies described by the Claimant's experts in this case are "household" Dust Bunnies and not the types of dusts involved in industrial fires and explosions. Claimant's experts were also very clear that the Dust Bunnies were "crucial" to the Dust Bunny Hypothesis as without them no fire would have happened.

The Claimant's experts did not know if the dishwasher door was open or closed when the fire first started, but after Step 7, per Claimant's hypothesis, the fire then spread to the kitchen. Also at issue in this fire was the deceptive appearance caused by the high fuel load (plastic) available in the dishwasher. However, as discussed in NFPA 921, kitchen appliances present a large fuel load (plastic) and therefore, per NFPA 921, extensive fire damage in and around a kitchen appliance is "not an indicator of a point of origin."

The Dust Bunny Hypothesis was outlined as follows:

Step 1 Mechanical Damage
Step 2 11-year Dust Bunny
Step 3 Dust Bunny Causes Electric Arc
Step 4 Dust Bunny Fire
Step 5 Wire Insulation Fire
Step 6 Unknown Fuel Fire
Step 7 Dishwasher Fire
Step 8 Kitchen Fire

The problems and inconsistencies with the 8-Step Dust Bunny Hypothesis were many and at each step and far too numerous to discuss them all here. However, in the context of the Scientific Method required by NFPA 921, the biggest problem was that the steps in the hypothesis were not experimentally tested. Instead, the Claimant's experts relied on "cognitive testing" and "thought experiments." While NFPA 921 allows for "cognitive testing" and "thought experiments," a single physical experimental test carries considerably more weight with judges and juries.

It's worthwhile to note that "cognitive testing" and "thought experiments" are useful and necessary concepts in NFPA-921 because it should not be necessary to burn down an entire building or explode a space shuttle to test a given hypothesis. However, when a hypothesis is easy, safe and inexpensive to experimentally test, that is clearly the most logical and convincing approach. In this dishwasher case, there were several Steps in the hypothesis that were easy, safe and inexpensive to experimentally test.

Per the Dust Bunny Hypothesis, the mechanism for Step 1 was the rubbing of the incoming 120v wires on the side of a hole in a metal junction box, most likely during transportation or installation. However, another defense expert conducted an experiment on an exemplar dishwasher by rubbing the wire at issue against the edge of this hole (in the exemplar) 200 times. The 200 rubs did not produce any cuts or breaks in the wire. Therefore, the hypothesis involved in Step 1 was tested and found to be false. Furthermore, an exemplar dishwasher obtained by the Claimant's experts was manufactured, shipped, and unpacked without any evidence of any breaks in the insulation of the wires at issue. That is also evidence that contradicts Step 1.

It is also worth mentioning that there was no physical evidence of any Dust Bunnies. Their existence was pure conjecture.

Dr. Fox tested Step 3 by placing actual Dust Bunnies between two live bare 120v wires. No electric arcs could be produced, even though the bare wires were practically touching each other.

Dr. Fox then tested Steps 4 and 5 by igniting a pile of Dust Bunnies to see if that Dust Bunny fire could ignite the wire insulation. The Dust Bunnies did not ignite the wire insulation, not even for a fraction of a second. Steps 4 and 5 were more aggressively tested by exposing the wire insulation to a butane flame. The butane flame did not ignite the wire insulation whatsoever as shown in the next video:

There were also a number of broader issues neglected by the Claimant's experts. For example, but not limited to, the Claimant's experts were aware that the Consumer Product Safety Commission data showed that this make and model of dishwasher had never had a fire and that there have been no recalls. However, there have been many recalls and fires of other makes and models of dishwashers.

The overall Defense Theory was that the fire started outside the dishwasher and that the electrical arcing found inside the dishwasher was the result of the fire and not the cause of the fire. This case did go to trial and Dr. Fox testified as part of the Defense Team and the jury verdict was favorable to the Defense.

Dr. Fox is a Certified Fire & Explosion Investigator and chemical expert with extensive experience in OSHA, EPA and DOT chemical regulations and chemical safety. He specializes in complex industrial chemical accidents, fires and explosions as well as chemical-related consumer product injuries.