Accession Number PB2013-101251
Title Forensic Investigation Techniques for Inspecting Electrical Conductors Involved in Fire.
Publication Date Jul 2012
Media Count 218p
Personal Author J. McAllister R. J. Roby
Abstract Many times, a fire investigator will conclude that a device was electrically energized at the time of a fire based on the presence of a bead on a wire. If an energized device is present in the area of origin, it is likely that it will be considered as a potential cause of a fire. Some training guides put forth that beads can only be formed from arcing on wires that were electrically energized when they were exposed to a fire or caused a fire. Therefore, the presence or absence of a bead on a wire can have a strong influence on the direction of a fire investigation. Hence, it is important to have a clear understanding of the various electrical and thermal conditions which can produce beads on electrical wires. The main objective of this research was to determine, experimentally, if distinguishing characteristics exist between energized and non-energized wires subjected to various types of fire exposures. The large majority of research published in the literature has not tested energized and non-energized wires under the same conditions. A total of more than 190 wires were tested under various fire conditions. Wire types included 12-gauge and 14-gauge solid conductors and 16-gauge and 18-gauge stranded conductors. The tests were conducted using a bench-scale, premixed flame impingement apparatus, a bench-scale 125 kW/m2 radiant tunnel apparatus, a 2/5-scale flashover compartment, and a full-scale flashover compartment. The use of various types of exposure conditions ensured that the characteristics on the wires (or lack thereof) were not caused by one specific type of thermal insult. Wires were tested in both an energized and non-energized state. Energized wires were tested under load and no load conditions. Under load conditions, the energized wires were plugged into a 110-120 volt power source with 9 to 13 amps of current. Under no load conditions, the wires were plugged into the power supply, but no current was flowing in the circuit.
Keywords Building wiring
Electric fires
Electrical activity
Electrical conditions
Electrical conductors
Electrical wires
Forensic investigation
Residential buildings
Thermal conditions
Wire failures

Source Agency Office of Justice Programs.
NTIS Subject Category 49 - Electrotechnology
89G - Construction Materials, Components, & Equipment
50C - Construction Equipment, Materials, & Supplies
Corporate Author Combustion Science and Engineering, Inc., Columbia, MD.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1302
Contract Number N/A

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