Apparent Electrical Fires
by Bernard Béland
Béland, Bernard. Apparent Electrical
Fire and Arson Investigator. Vol. 47. No. 2 (December 1996). p 19-21.
A fire is a complex phenomenon even if it involves only a match or a
candle. A fire in a building is a real challenge and its investigation is
full of pitfalls. It is easy to err concerning the point of origin, and
even more so in relation to the cause. The problem is usually not of finding
"a cause" (there are normally numerous possibilities) but finding
"the cause" to the exclusion of all others. Pointing electricity
as a cause is usually quite easy and often wrong since electrical wires
and devices are almost everywhere in any building. These devices will obviously
be damaged by the fire. Numerous authors have challenged these electrical
fires (1-4). Often electricity is pointed without any evidence except for
its mere presence in the area of origin of the fire. That mere presence
is an extremely weak evidence since it is almost always so. Most of the
fire investigators are aware of cases in which electricity was pointed as
the cause to find later that arson had been committed, that dangerous processes
took place, such as welding, just before the fire or even that electricity
was not connected in the suspected circuit.
In this article a few field cases will be considered in which electricity
was pointed as the cause without any evidence. In these cases, legal actions
were taken against the manufacturer, the electrician or other persons who
had something to do with the electrical installation. In one case, extreme
hardship was suffered by the electrical contractor. It is realized that
these cases may not be typical of most fire investigations. Still, such
cases are quite numerous. Such cases were encountered in numerous situations
by this author.
STICKING CONTACT IN A BREAKER
During an evening, a teenager was cleaning bicycle parts with gasoline
in a garage attached to a house. A fire was ignited accidentally, and was
extinguished in a matter of a few minutes. Later, during the night, a fire
started in the garage and eventually destroyed the garage and damaged the
house to render it a complete loss. In the absence of any specific evidence,
it would seem that the most probable cause of the second fire is a rekindle
of the first fire that had not been properly extinguished.
A fire investigator found an arced 8/3 copper cable that fed an electric
range. He checked the 40-A breaker that protected that circuit and found
it in the tripped position. He then checked the breaker with an ohmeter
with a buzzer and found that it had not opened. He then concluded that the
breaker contacts had welded and eventually the breaker manufacturer was
sued. He unhooked the breaker, put it on his car seat and brought it home.
From that point, everyone that tested the breaker found the breaker contacts
open, both electrically and physically. It was claimed that the car vibrations
had broken the contacts loose.
The fire investigator was the only one that ever detected the closed
contacts, the surface of which were normal. He probably misused the meter
and did not properly interpret the reading. The instrument was easy to misuse
and the fire investigator was not competent enough in electricity to properly
use the instrument. An even more likely explanation is that the measurement
was made while the breaker was still connected in the panel. In such a case,
more likely than not, a measurement will show a low resistance even if the
breaker is in the open position. This is due to the numerous other connected
circuits and short-circuits in a burned house. To properly check the breaker
for shorted contacts it has to be disconnected from the electrical circuit.
The theory of the fire investigator is that a short circuit was developed
in the 8/3 cable and the breaker failed to open. The cable then became very
hot and started the fire. There are many faults with that argument. The
cable, where it was not damaged by the heat of the fire had no sign of overheating
even between the arced spot and the breaker panel. Furthermore, that breaker
panel was protected by a 60-A main breaker. In the event of a failed 40-A
breaker, the circuit was still protected by the 60-A breaker. Assuming a
properly functioning 60-A breaker, any short-circuit current would produce
a temperature rise of the cable by about 5 to 10°C under the worse conditions.
An even worse situation would be an overload of about 75-A Under that condition,
the breaker could take a long time to open. Assuming it does not open, the
temperature rise of the cable would then be 40°C above ambient. The
fire investigator never considered that 60-A breaker as a further protection.
Notwithstanding all these weaknesses of the case, the fire was supposedly
of electrical origin and the breaker manufacturer was sued.
FIRE IN WOOD SHAVINGS
In a storage building, a fire was discovered in the attic space around
a recessed lighting fixture. The fire was extinguished quickly and the maximum
depth of char on wooden studs was about a quarter inch deep. The attic space
was insulated with wood shavings to a depth of over one foot. That insulation
was heavily charred and many fire debris were spread away some distance
from the point of origin. Some ten hours later, the fire rekindled around
the same area but was not controlled until the building was a complete loss.
After the first fire, an electrician was called. He disconnected the
circuits that had been damaged by the fire or water and installed some new
cables. On the evidence of beadings, an engineer pointed these electrical
repairs as the cause of the fire and the electrician was sued.
It should be quite obvious that the most probable cause of the fire is
a rekindle of the first fire that was not completely extinguished. The electrical
cause is just a remote possibility for which the evidence is weak or non
existent. It must be admitted as a possibility in the sense that almost
anything is possible. Again a remote possibility was pointed as the cause,
while a more obvious cause was rejected or neglected. Beading is no evidence
of the cause; it occurs at numerous places in almost all fire, including
the area of origin. The evidence of beading would be very useful if it was
unique and that only one particular meaning could be attributed to it. But,
this is not so.
ARCED AND BEADED CABLE
In a tavern, there was a long and large corridor that lead to the washrooms.
The ceiling was covered by cellulosic acoustic tiles and had combustible
thermal insulation such as cardboard sheeting. Such a material can be ignited
by a match in about one second. The ceiling in the corridor had an opening
to give access to the attic space with the use of a ladder if necessary.
At the time of the fire, the building was under extensive renovation,
including work in the attic space. During the day, the tavern was closed
so that work could be done more easily and would open during the evenings
for the patrons. The day of the fire, numerous workers went up in to attic
for work on electricity, plumbing, refrigeration and numerous other reasons.
Power tools and propane torches had been used. There was temporary electrical
wiring including 300-W lamps with extension cords and, of course, the regular
wiring. There were also recessed lighting fixtures.
At the time of the fire, during the evening, there was no one in the
attic but the trap door above the corridor was left open. Numerous patrons
of the tavern were on the premises. One of the clients noticed a glow from
the attic space above the open trap door. The fire was reported but the
building was eventually destroyed to the ground.
A fire investigator found a melted copper wire with beading. That was
pointed as evidence of the cause. The electrician was sued causing great
hardship to his business. The investigator concluded that he had eliminated
all causes but that of the beaded wire and, without a doubt, that was the
As usual, there were numerous evidences of beadings in many other cables.
None of these could be eliminated as a possible cause. The one that was
retained was handy since it was one that was installed as temporary wiring
a few days before the fire. The destruction was so advanced that there was
no clear evidence as to the point of origin. In fact, most of the attic
space was a possible point of origin. The glow from the attic was seen at
the point of the open trap door, but that does not suggest the point of
origin. The origin could have been anywhere and the glow would always be
seen at that opening, particularly in a poorly lit area.
Obviously, in that fire, besides arcing, there were numerous other possibilities.
Among the most obvious one would be the actions of one of the workers during
the day such as smoking materials and soldering of copper pipes. A thermally
insulated recessed lighting fixture, one of the extension cords or a light
bulb are other possibilities. Not to be neglected is that a patron could
have thrown a lit cigarette in the attic. In this particular instance, the
judge retained that temporary wiring as the most probable cause.
A GARAGE DOOR OPENER
A man drove his car back home into the garage using the automatic garage
door opener for both opening and closing the garage door. He then went to
the house. A fire in the garage was discovered about 40 minutes later. The
roof of the garage was completely destroyed and the walls were also burned
completely except for the first foot or so close to the ground. The char
pattern on the remaining of the walls was almost uniform over the whole
perimeter of the garage. Similarly, the car was destroyed to leave only
distorted steel. When the fire was discovered, the detached garage was fully
From the above evidence a fire investigator concluded that the fire started
in the center of the garage because of the uniform char pattern. That would
seem to be a weak argument since one has always a uniform char pattern when
almost everything is burned. Since the lower parts of the wall were not
completely burned, he further concluded that this was a "high fire"
and it must have started at the ceiling level. Again, that evidence is very
weak since most fires that last for some time do more damages at the higher
levels than at the floor level. This is so even if the fire starts on the
floor. The garage had a concrete slab on ground.
In his report, the fire investigator, using the above arguments, concluded
that the only possible cause for the fire was an electrical malfunction
of the garage door opener. He was prudent enough however not to be specific
on the failing process or the part that failed. The manufacturer of the
garage door opener was sued. In his report, the fire investigator neglected
to address many points such as that of the motor that was thermally protected.
Had the motor been stalled for any reason, a fuse would have blown quickly
and the thermal protection would have opened.
There was no obvious causes for this fire although there were quite a
few possibilities besides the door opener such as the lights on the ceiling
and the electrical wiring in the garage. The car could also have started
the fire for numerous reasons. Furthermore, the driver was a heavy smoker;
a dropped cigarette is then a further possibility. In this case, with the
evidence available one should have refrained from giving a probable cause
since all causes were about equally probable although, the most likely cause
is smoking materials. The driver denied that he had smoked; however, a passenger
that was dropped off about one minute before the car was parked in the garage
was sure that the driver was smoking at the time of the drop off.
A HEAT TAPE FIRE
In a crawl space underneath a house, a fire was ignited and eventually
went up into the house through holes made to pass pipes. A heat tape installed
on a water pipe was damaged for a length of a few feet. The resistive wires
were severed. The point of origin was not very clear but part of the tape
was in that area. It was concluded that a faulty heat tape arced and caused
that fire. The remains of the tape was tested. It was found to be open-
circuited at two points where connections are made. Obviously the tape could
not provide any heat even if it had been connected and the thermostat had
been on. At the time of the fire, the ambient temperature was high enough
so that the properly operating thermostat had to be in the off position.
This make up three open-circuits in series. It would seem to be extremely
unlikely that all three had been on before the fire and were off after the
fire. These three open-circuits had never been in the fire area. They had
only been subjected to water from the fire-fighting.
A few filed cases of fires have been discussed in which electricity had
been pointed as the cause. In all instances, the evidence was very weak
or nonexistent. In other cases, the electrical cause was a possibility to
consider but with further investigation, had to be rejected The mere presence
of electrical cables or devices is often used as evidence of the cause.
The investigator should resist this easy way out of a case. Electricity
is so much used in any building that, in most cases, there are numerous
electrical wires in the area of origin. The cables are always damaged such
as burned insulation that produces short-circuit and arcing. The mere presence
of electrical cable, even with evidence of arcing, should not be used as
evidence of the cause. However, under certain circumstances, certain facts
could help point to the electrical cause. These facts should be significant.
The mere flickering of lights when a motor is started or the use of a 20-A
fuse instead of 15-A are not, by themselves, sufficient evidence to point
In a typical house, there is about one foot of cable per square foot
of floor area and, sometimes, much more. Over hundred feet of flexible cord
is quite common. The reader may be surprised to learn that a typical house
has about 50 electrical motors. Most people think that they have just a
few. An air conditioner has compressor and fan motors. A refrigerator has
a compressor motor plus, sometimes one two three motors for air circulation
and cooling of the heat exchanger. Most furnaces have two motors for the
burner and the heat exchanger fluid. Even a microwave oven has a motor for
the cooling fan of the klystron.
These cases were selected to show how easy it is to err in pointing a
cause for a fire. This is particularly true of fires in which electricity
is one of the possibilities. It shows that fire investigation is not easy
and numerous errors are often made. Most of them are probably from incompetence
and misinformation. It should be stressed that this selection of cases is
not necessarily typical of fire investigation. Another set of cases could
have been chosen to illustrate just the reversed situation in which very
good investigations were made. However, these field cases should not be
considered as exceptional. Almost all of these cases were encountered on
a few occasions. In some fires, there are many fire investigators. It is
not unusual to have as many different assumed causes for a single fire as
the number of fire investigators. Even the number of points of origin sometimes
approaches the number of experts retained for the case. If there are four
causes for a given fire, it would seem logical to assume that at least three
causes are wrong. In such a case, the expert most likely to be right is
the one who has classified the cause of the fire as unknown.
This article has illustrated the difficulty in investigating fires. Numerous
pitfalls were discussed. Although these cases were selected to show the
poor investigation in some instances, other cases could have been chosen
to illustrate the reverse situation.
1. B.V. Ettling, "Are We Kidding Ourselves?", F&AI, Vol.
34, No. 4, June 1984, pp. 19-22.
2. J.F. McPartland, "AU These Electrical Fire? - Hogwash!, The National
Fire and Arson Report, Vol. 2, No. 3, September 1983, pp. 5 and 10.
3. B. Béland, "Examination of Electrical Conductors Following
a Fire," Fire Technology, Vol. 16, No. 4, November 1980, pp. 252-258.
4. B. Béland, "Electrical Damages - Cause or Consequence?,"
Journal of Forensic Sciences, Vol. 29, No. 3, July 1984, pp. 747-761.
About the Author
For the past 30 years, Dr. Béland has studied fires under laboratory
conditions and also at fire scenes. Many of the fires, including full size
fires in buildings, were started intentionally to study their behavior.
Dr. Béland specializes in the study of ignition, thermal transfer
and electrical causes. Many systems and devices were used in his experiments
to study their outcome and to determine what types of damage could be associated
with the causes that resulted in the fire. He has also experimented with
numerous systems to determine under which conditions they could constitute
Dr. Béland's research has resulted in the printing of over 100
technical articles in specialized journals such as: L'Ingenieur, Fire Technology,
Journal of Forensic Sciences, Fire & Arson Investigator, Power Apparatus
and Systems, Electrical Business, Proceedings of the Institute of Electrical
Engineers and others.
Dr. Béland has investigated over 900 fires and electrical failures
in which a total of 300 lives have been lost. He is retained by equipment
manufacturers, power companies and research centers. Dr. Béland has
done consulting work and lecturing in eight Canadian Provinces, 37 states
throughout the U.S., four European countries and New Zealand. He has served
as an expert witness in approximately 100 cases for numerous jurisdictions.
Dr. Béland has taught at numerous universities in Canada. He recently
retired from the Universite de Sherbrooke as a Professor in the Department
of Electrical Engineering. Dr. Béland is currently a private consultant
in his own firm.
Reprinted with permission.