Reference
Cause and Origin versus Origin and Cause?
By Mark Hughes, P. Eng.
© 2000 Sintra Engineering Inc.
As fire investigators, we are often asked to examine the cause and origin of a fire. While all experienced fire investigators know the difference between the terms "origin" and "cause", there is also significance to the order in which the terms are presented.
NFPA 921 defines Cause as "the circumstances, conditions or agencies that bring together a fuel, ignition source, and oxidizer (such as air or oxygen) resulting in a fire or combustion explosion." The term Origin is not specifically defined but refers to the "Point of Origin or Area of Origin". If one was to look up Point of Origin you would find it defined as "The exact physical location where a heat source and a fuel come in contact with each other and a fire begins."
The terms seem obvious, and both meanings clear. How can the order in which the terms are presented affect a fire investigation. Is it meaningless semantics?
In general a proper fire investigation, following the "scientific" method outlined in NFPA 921 always follows a similar pattern. In most cases, the fire investigator arrives at the fire scene, proceeds to examine the remains from the fire and identifies the area of origin. A variety of information sources (in addition to the fire scene) including information from witnesses, information from first responders and information from the building owners is use to narrow the area of origin. Once the area of origin is established the trained fire investigator will look in that area for possible causes of the fire. Without the establishment of an area of origin (even if there are multiple areas of origin), the cause will be very difficult to establish.
Many investigators, particularly those in the private sector, are often told of the cause of the fire, before arriving at the fire scene, and asked to prove it. Often an insurance adjuster may have an idea as to the cause of the fire and is be looking for an opportunity to subrogate. Normally any investigator worth their salt will still independently verify the cause of the fire, after the examination of the fire scene and the identification of the area of origin. Despite this potential conflict (wanting to prove a specific cause versus finding the cause independently), some investigators fall into the trap of assessing the cause first without determining the area of origin.
I found was an article at the Interfire VR site (www.interfirevr.com) by Dr. Bernard Beland. The article had originally been published in Fire and Arson Investigator (September 1997). In this article, Dr. Beland stated that there are many exceptions to the rule of finding the origin first and then finding the cause. In fact the article implies that digging in a fire scene for the area of origin is often a waste of time.
Dr. Beland's article then describes two case studies, one involving a problem with a floating neutral and the second with an external heat source (a propane torch). In both cases, Dr. Beland states that the cause was found without identifying the area of origin and that the other investigators wasted their time digging in the dirt to investigate the fire. In both cases, apparently the other investigators found beaded wires at the scenes and attributed the causes of the fires to be electrical.
Maybe these investigators did do a poor job investigating the fire and came up with the wrong conclusion, but what Dr. Beland has neglected to state in his article is that any proper fire investigation would still examine burn patterns within the fire scene and use them to determine the cause. Beaded wires are just a piece of the puzzle. The examination of the beaded wires, in combination with other information from the fire scene, is part of the methodology of fire investigation. If an individual fire investigator does not adequately investigate the fire, then the cause may be incorrectly reported, however, this does not prove the methodology incorrect. Dr. Beland's assertion regarding finding the cause without determining the area of origin is misleading and incomplete.
Fire investigation is the process of determining the Origin and Cause of a fire, not the cause and origin.
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