These are not "terms." They have been put fourth as positive "indicators" of the fire origin That is, if you find this comparative fire damage or fire pattern, it means this ("If this, then this" would be familiar to most who have reviewed any computer programming) These have been used as unqualified laws or "rules of thumb."

What your examples are describing is adding qualifiers to these "rules of thumb." The question becomes what "science" and methodology are you using that would provide reliable added qualifiers to these "rules of thumb?" How does a localized fire condition add reliability to "the area of greatest damage is the area of origin? How does a localized fire condition add reliability to "the presence of a v-pattern points to the fire origin?" These are not fundamentals that can be applied in all cases. These indicators can be true in some cases, but not all cases. That is why they are not reliable.

With that said, the presence of a "v-pattern" and "the area of greatest damage" can be used as evidence to test fire origin hypotheses. The use of the fire damage and fire patterns in this manner is subtly different than using it to an indicator that elucidates the fire origin. That is, as discussed in NFPA 921, you can test an origin hypothesis by assuming a fire starts in your hypothesized area of origin and you analyze the growth and spread of the fire to see if it is consistent with the damage (and timing) that occurred. This is not a trivial concept. It is one of the most important method of hypothesis testing that gets neglected in most fire origin and cause investigations that I am exposed to. So this evidence can be used, but not as indicators or "rules of thumb."

Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
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