After a fire claims the lives of two children, a heater manufacturer is left to blame. But ongoing investigation uncovers a case of mistaken identity.

When a fire broke out in his home before dawn, Christmas Day turned to tragedy for a migrant farm worker and his family. Although he and his oldest child escaped unharmed, the fire killed two of the children and inflicted severe thermal burns on another child and his wife.

Obviously, the first question that comes to mind is: What caused the accident? Several fire investigators and consulting engineers declared the middle child's bedroom as the origin of the fire. They believed a defective electric heater (located on the floor in the center of the room) or a defective extension cord (coiled beneath the head of the oldest boy's bed) started the fire.

Although investigators uncovered no conclusive evidence, they found the name of an electric heater manufacturer on an empty cardbox at the scene. This manufacturer was later named in the suit. Since the value of this fire totaled in the millions of dollars, insurance carriers for the electric heater manufacturer, extension cord wire manufacturer, the retailer who sold the heater, family farm corporation, and the individual family farmers all paid their policy limits ($1,000,000 each) to settle out of court.

Despite the settlement, questions remained unanswered. To help reconstruct the accident, let's take a closer look at the events leading up to the fire. It all started when a claims adjuster (unhappy with his original experts' opinions) hired a new fire investigator to determine if the heater was "on" at the time of the fire. This investigator asked his secretary's husband (characterized as a "mechanical type") for his opinion. This "mechanical expert" testified that because the heater's plastic housing melted and enshrouded all of the internal components, he could not determine the location of the switch or visually see if it was "on" Hoping to extract the switch, he decided to cut the heater into sections. Fearful of destroying useful information, he picked a segment width slightly larger than the known width of the switch and made seven cuts. This so-called expert was obviously unaware of the standard forensic technique of X-raying before destructive testing.

After the settlement, the heater manufacturer's insurance carrier decided this cutting had denied them an effective defense. Therefore, they filed a cross complaint against the fire investigator, his "mechanical expert," and their insurance company for spoliation of evidence to recover the manufacturer's million dollars. Next, attorneys for the heater manufacturer hired me to determine whether the destructive examination of this evidence had unduly limited its defense. Because of the unique nature of this secondary suit, I needed a new cause and origin scenario that included a heater defect. With the house demolished, this required a complete reanalysis of the fire scene photos and numerous depositions. Although casual observation of the exterior of the heater's remains was enough to show it had not directly ignited the fire, I could see a heater defect could possibly have started a fire elsewhere.

After some digging, I discovered the mother had purchased two electric heaters. Taking the advice of her husband, the wife asked his brother for an extension cord. He gave her one using No. 16-3 conductors that appeared twisted and taped to another cord comprised of 16-2 conductors. There was no female connector on this hybrid cord. She followed his instructions to purchase an electrical box with a receptacle and attach it to the cord. To affect a male connector, someone spliced on a 6 in. length of No. 18 insulated wire with a molded plug. Next, she connected the completed "extension cord" to one of the two heaters (located in the center of the middle bedroom), then passed it under the oldest boy's coil spring bed with cotton mattress (where she coiled the excess length), then routed the cord along the wall, through the bedroom door, around the corner through another door to the adjacent living room, and finally plugged it into a receptacle behind the couch in the living room. (The second heater's location never surfaced.)

Swayed by the damage and burned hole in the bedroom's floor, numerous investigators claimed either the makeshift extension cord or the heater started the fire in the highly combustible bedroom. However, there was no evidence to that effect on these objects. Much to the contrary, the lack of arcing showed at the time the heater and that portion of the extension cord within the bedroom burned, the power had already tripped off. The fire could not have started in the bedroom! Investigators eliminated the living room as the origin, because the Christmas tree remained unburned.

They only found arcing at the extension cord's plug behind the couch in the living room. This took place in the 6 in. length of No. 18 wire at the plug. A classic "V" pattern burn on the Sheetrock wall indicates the fire's origin centered behind the couch (with its vertex at the wall receptacle that powered the heater).

So how did the fire get into the bedroom? The extension cord had the insulation burned along the top of its length, from the living room plug, all the way into the bedroom. The weakest link, the No. 18 wire, overheated, melted, and ignited after arcing. Preheated by the heater's high current, the cable's insulation ignited and acted like a fire cracker fuse to bring the ignition energy into the bedroom where it found the substantial, readily ignitable, fuel load.

Unfortunately, the fire investigators made premature determinations without the benefit of the witnesses' statements. With careful reading, I learned the mother and son could not remember if both heaters were the same brand. Awakened by heat and smoke, the mother first observed flames in the corner of the hallway formed by the living room and children's bedroom doors. She crossed this area, woke up the kids, and exited back into the hall with the two youngest boys (where they received substantial burns). The eldest boy went the opposite way, out the window. Ironically, he received no burns; even though investigators claimed the fire started under the head of his bed or in the center of the room he'd just crossed! The witnesses' statements again precluded the fire from starting in the bedroom.

An unusual spring imbedded in the heater's melted plastic housing was not present in an identical factory-supplied undamaged heater. Fire investigators dismissed this as a bed spring, acknowledging the fact that they found the heater remains in the center of the bedroom floor. This spring was about a third of the size of the available bed springs, and no one gave a plausible explanation for how this spring managed to travel to the center of the bedroom and leap into the melting heater.

The defense had been vulnerable because the plaintiff could have proposed the fire started in the living room behind the couch, due to a short-circuit defect within the heater's tungsten coils that caused excessive current to pass through the 13A-rated heater (and the "extension cord"). To disprove this theory, I needed to inspect all the heater wires intact to assure there were no arc and discoloration marks. Without that, I could not say with certainty the heater had no defects. In the X-ray, I could see the 1/16 in. saw blade kerf of the seven cuts severed the tungsten coils 80 times and thus destroyed access to a total of 5 in. of the heater's wire. This theory shows how the defense's evidence in the initial suit had been compromised.

An opposing expert in this secondary action discovered another brand of heater that had an identical spring to that found in the burned one. Further comparisons confirmed the burned heater was not the same as those manufactured by my client! All of this information had been equally available before the original settlement, and thus was not affected by the cutting. Legally, there was no spoliation. Not only had the initial investigators failed their clients, the accused heater manufacturer's insurance company needlessly gave away a million dollars when they had the best defense. It wasn't their heater!

Crawford is a Forensic Electrical Engineer and Electrical Contractor, Palo Alto, Calif.