Investigations of Fires of Electrical Origins. Factory Mutual System.
Abstract: This article provides guidelines and techniques for
investigating electrical fires. The article is in outline form and starts
with some basic electricity principles. The article then discusses possible
electrical ignition sources and lists common indicators of each. An overheated
wire is an example of a possible ignition source and can be identified by
swelled insulation, internal charring, discolored conductors, and improper
or defeated fuses. The other sources the article outlines are arcing, an
overheated apparatus, and lightning.
The article lists important safety rules regarding electrical systems.
The most important rule is to always assume that there is still power in
the structure even if it has been turned off or the meter has been removed.
The next section of the article provides a list of questions to ask witnesses
and people who occupied the building. Included are specific questions about
the electrical systems of the structure. Witnesses should be asked about
what they saw, heard, smelled, and about the weather. Questions about the
fuses, circuit breakers, switches, wires, and appliances should be asked
of the people who lived, worked, etc. in the building.
The last section discusses wiring, enclosed disconnecting switches, and
relays. The article lists problems in these areas and offers solutions on
how to fix them to prevent fires. For example, if a switch blade is burned
or oxidized from overheating, the article suggests cleaning the blades and
providing new contact clips if the tension is gone. There are also other
suggestions on how to fix common problems in these areas.
For more information, contact:
Factory Mutual Research Corporation
1151 Boston-Providence Turnpike
Norwood, MA 02139
Phone: (781) 762-4300