NCJ Number
90684
Journal
Fire and Arson Investigator Volume: 33 Issue: 4 Dated: (June 1983) Pages: 23-32
Date Published
1983
Length
10 pages
Annotation
This article identifies some common conceptual errors in fire investigations pertaining to why fire burns upward, the flammability of old wood, the cause and point of origin of the fire, fire code violations, the production of combustible gases, and determination of electrical fires.
Abstract
It is common to hear even from so-called experts that fire burns upward because it is searching for oxygen, but in fact fire burns upward because its hot gases are lighter than ambient air and therefore rise. Mention is also often made of the high flammability of old wood compared to wood which is only a few months old; however, the moisture content of wood does not decrease indefinitely with time; it reaches its final value within a few months, then changes constantly by a small percentage throughout the seasons to adjust to the varying conditions. Older houses burn more easily because of construction characteristics rather than the age of the wood. Frequently, investigators will falsely identify a fire cause to be malfunctioning electrical equipment which is found damaged at the fire's point of origin, but the damage to the electrical equipment could have been caused by the fire rather than being the cause of the fire. Further, simply because a fire code has been violated in certain aspects does not mean that such violations contributed to or caused the fire. The fire cause should be established independent of any observed or reported code violations. Fire investigation reports often state that a cable in a wall has produced a fire. It is only in very particular and exceptional circumstances, however, that combustible gases are produced to cause a fire. Detailed attention is given to electrical fires, and the general conclusion is drawn that it is usually difficult, if not impossible, to recognize electrical malfunctions that are fire causes rather than fire consequences. Photographic illustrations are provided along with 12 references.