Vytenis Babrauskas, Ph.D
Arc mapping was first introduced in the 2001 edition of NFPA 921 and was subsequently expanded so that in the recent editions it constitutes one of the four main methods for determining the origin of a fire. Careful consideration of engineering principles and large-scale experimental studies on the subject indicates that the relevance and prominence of arc mapping as a leading indicator of fire origin is greatly overstated. The technique is valid and applicable only in some very limited scenarios. Yet it has seen very extensive use in recent years by investigators preparing fire reports. In many cases, such attempted use of arc mapping is based on incorrect and invalid hypotheses, which are often implicitly assumed to be true instead of being explicitly stated. The following are myths: (i) An abundance of arc beads at a given locale means that fire originated in that area, while a paucity of arc beads indicates that it did not. (ii) When multiple arcs are present on a circuit, the direction of arcing will necessarily proceed upstream towards the power source. (iii) If an appliance is the victim of a fire, internal arcing will be primarily near the exterior of the unit, while arcing deep inside indicates a fire origin at that place. NFPA is urged to revise NFPA 921 to eliminate arc mapping as one of the four main methods for establishing fire origin, and to subsume it under the more general category of “fire patterns.” In addition, it is important that NFPA 921 reduce the implied general utility of the method and provide more explicit information on its interpretation and its limitations and on the circumstances under which it may be a valid method for assisting in the determination of the fire origin.
Vytenis Babrauskas, Ph.D.
Short circuits to building wiring can happen due to electrical mishaps, or as a result of fire impinging on the wiring. In either case, this may cause arcing. It is sometimes erroneously assumed that this must produce signs of ‘electrical activity,’ which is a term often used by fire investigators to mean discernable arc marks or arc beads. While such artifacts may indeed be produced, it is shown that it does not necessarily happen in every case. Shorting and arcing (whether due to fire or due to an accident) may occur without leaving physical evidence that is discernable as an arc bead. Ejecta also may, but do not have to be produced. Some variables have been identified which can influence the size of arc beads, when arc beads are produced. But stochastic aspects dominate, and no predictive correlations can be expected. It is also shown that there are no prediction methods available to establish if an arc locale will result in severing or welding together of conductors.
From Out of the Abyss...
This week’s article from the past is titled Incendiary Fires Can Be Spotted and was written by Benjamin Horton, CPCU, who was President of the National Adjuster Traing School in Louisville, Kentucky.. It is taken from the Decembe 1968 Vol. XVI No.5 issue.
Incendiary Fires Can Be Spotted
In the new issue of NFPA Journal®, President Jim Shannon said the Association will focus on the leading causes of home fires, including cooking. "We also need to continue to push hard for home fire sprinklers. That's still a large priority for NFPA, and we plan to work very aggressively in 2014 on our residential sprinkler initiative," he said.
From: The Desk of Scotty Baker
To: The CCAI Training Committee
Over the last several training seminars, even as an old hand, I have learned new information concerning fires and how they do what they do.
Get started today
The focus will be on Interviewing, Report Writing and Fundamentals
Register now online or Fill out the registration form and email, mail or fax it
This recall involves Heat-N-Glo® and Heatilator® Corner Unit Series indoor gas fireplaces. The fireplaces are LP or NG-fueled corner units with tempered glass fronts. The following model numbers are printed on the unit rating plate, located near the controls used to operate the units, and in the instruction manual.
See the full details at CPSC
This recall involves indoor 2-light fluorescent light fixtures that range in size from 18 inches to 4 feet long. The fixtures were sold in white and can be mounted from heights between 8 and 12 feet. A date code between 182 11 (July 1, 2011) and 090 15 (March 31, 2015) is affixed to the fixture near the ballast in a DDD YY format. Catalogue and model numbers are located on the second line of a label affixed to the inside of the fixture. Catalogue and model numbers included in the recall: DLE217RLP, DLE217RLPB, DLE 232RLP, DLE232RLPB, SL232R, SL232R/1, SL232RPC, SL232RTP, SLNR232R, SLNR232R/1, SLNR232RCHR, SLW232R, SLW232R/1, SNF115R, SNF117R, SNF125R, SNF217R, SSF217R, WP217R, WP217RNKLLU, WP232R, WP232RLU, WP232RNKL, WP232RNKLLU and WP232RNKLRL.
Click here for full details from CPSC.
Almost every consulting engineer works with codes and standards on a daily basis, but do you know the difference between a code and a standard?
According to the National Institute of Standards and Technology (NIST) Circular No. A-119, Revised, a standard is "[t]he definition of terms; classification of components; delineation of procedures; specification of dimensions, materials, performance, designs, or operations; measurement of quality and quantity in describing materials, processes, products, systems, services, or practices; test methods and sampling procedures; or descriptions of fit and measurements of size or strength." In plain English, a standard consists of technical definitions, procedures, and/or guidelines that specify minimum requirements or instructions for manufacturers, installers, and users of equipment. This can be done by specifying either the methods or the results; the latter is known as "performance specifying." Most importantly, a standard provides standardization or agreement within the industry, which translates to a common reference among engineers, manufacturers, and bidders.
Since the 1989 Montreal Protocol and its successor agreements, the world of refrigerants has been marked by change. In the search for more environmentally-preferable refrigerants, technology has moved from chlorofluorocarbons to a host of alternative substances. Many of these substances are serving as interim measures, until the phase-out of ozone-depleting and global-warming refrigerants meets the targets set by the U.S. Clean Air Act. The journey toward compliance has caused the HVAC equipment and appliance industries to revisit the potential use of substances that have good environmental and thermodynamic properties as refrigerants, but which are also, unfortunately, flammable.
This recall involves Cree LED T8 lamps used indoors to replace traditional two pin T8 fluorescent tubes. The white lamps have a cylindrical shape and measure 48 inches long. The affected units are marked as “BT848 Series Lamp” with the product part number on the lamp itself or printed on a white label affixed to the lamp. A four digit date code is printed on the lamp under a statement that reads “Compatible with Instant Start, Rapid Start and Dimmable Electronic Ballasts.”
Read the details at CPSC
Page 5 of 17
CCAI Advertisers enjoy unprecedented exposure to professionals in the public and private sector with tens of thousands of targeted visitors each year looking to arson.org for critical information on the state of fire and arson investigation in the United States and worldwide!
Banner ads should be formatted to 699 x 125 pixels, JPEG or animated GIF or Flash SWF, 100Kb or less.
Annual advertising rates available.
This is the official website of the California Conference of Arson Investigators.
The information published on this website... more...
Copyright© 2010. California Conference of Arson Investigators. SiteAdmin. Web Design by Todd Lando