Fire Investigation: The Case
by LP SThe fire in question occurred at a restaurant. When the fire department arrived, heavy smoke was observed but no flaming could be seen. Firefighters did not locate the source of the smoke until the fire - emanating from the floor/ceiling which separated the area from a storage room below - broke through the kitchen floor. Both local fire department investigators and a private fire cause and origin investigator [hired by the party who ultimately became the plaintiff in the case] investigated the fire. Their work determined that the fire started in the void space between the basement storeroom ceiling and kitchen floor.
In the process of conducting that investigation, a fluorescent light fixture which had been mounted to the storeroom ceiling was located in the fire debris. As part of recognized fire investigation processes, three separate investigators concluded by a process of elimination that the fire started at the fixture location. Contrary to Mr. Burnette’s comments, the investigators are reported to have ruled out associated building wiring as a fire cause to their satisfaction based on the evidence available. We need DP on this one!
Like most fluorescent fixtures, the damaged but intact fixture which was recovered contained a ballast. A ballast is a transformer which converts line voltage to higher voltages capable of powering a fluorescent tube.
The private cause and origin investigator disassembled the fixture and determined its manufacturer. The ballast was determined to be manufactured by Magnetek, an eventual defendant in the case.
An additional expert whose qualifications included a Ph.D. in physics and 20 years experience in studying fires and explosions also evaluated the evidence. He observed oxidation patterns on the fixture and discoloration of the ballast's heating coils. These observations indicated that, prior to the structural fire which occurred, the ballast had shorted, causing internal overheating.
Technical Issues:
This ballast design in this case contained a device called a thermal protector. The thermal protector is a combination temperature sensor and switch with a thermal reset feature. When functioning normally, the thermal protector would de-energize the ballast when it sensed temperatures exceeding 111oC [232o F]. This would cause the light to go off signaling to building occupants that something was amiss with the light installation. When temperatures at the thermal protector fall below 111oC [232o F], the thermal protector restores power to the ballast and the light will once again illuminate.
In the fire at issue, examination of the [incident] thermal protector in the ballast demonstrated that it continued to function even after the fire had occurred, effectively eliminating a temperature excursion based on a thermal protector malfunction before the fire. The Court of Appeals’ opinion is silent in terms of testimony as to what management or staff knew about the ballast. However, if it had been cycling, that would have been a sign that thermal failure was taking place.
As part of the investigative process, tests were conducted by plaintiff's experts who faulted exemplars of the ballast at issue and observed the results. In this case, the ballast reached temperatures of 340o F cycled off and then cycled on once again once cooling
occurred. That testing demonstrated that routine operation of the ballast would occur at temperatures in the range of 149oC [300 o F] as it cycled on and off which is below accepted short term wood ignition temperatures but significantly higher than safe wood exposure temperatures in the range of 90oC [XXX o F] as allowed in our building and mechanical codes and common UL and ANSI standards. at . It is especially critical to consider that The Court of Appeals wrote in its opinion that it believed - based on the evidence provided to that court – that wood ignition occured in all cases at temperatures greater than or equal to 204 o C [400o F].
The plaintiff’s expert expressed the opinion that ballast operating temperatures observed as described above - were lower than ignition temperatures normally accepted for wood adjacent to the ballast. However, the same expert testified in deposition and sought to testify in the trial court that the magnitude of this overheating while below commonly accepted temperatures for the ignition of wood, was sufficient to cause the ignition which occurred because the wood had been subjected to these elevated temperatures for extended periods of time. He characterized that exposure as causing what the court – based on the limited information provided to it - misguidedly referred to in its writings as “pyrolysis”. Accordingly, the plaintiff’ s expert provided an opinion that a short circuit in the ballast created moderate but extended overheating which eventually caused ignition. It was this theory that the Federal Appeals Court referred to as a "pyrolysis theory." That was the opinion upon which this case rose and fell.
The defendant on the other hand claimed that such a “pyrolysis theory” could not be relied on to explain the start of the fire. In its writings, the courts characterized the proffered theory as suggesting " that ……wood can catch fire at temperatures below 400o F if it is exposed to such temperatures over a long period of time." The court’s writings also indicate that it believed – based on the evidence presented - that temperatures in excess of 204 o C [400o F] were in all cases necessary to ignite wood. This is simply not true. One needs only to look at the 70+ year old table presented above to see that such a threshold number was inaccurate.
However, the trial court granted the Motions to exclude the plaintiff’s expert’s opinions and entered a Summary Judgment – a process that provided a finding for the defendant.