Electrical Power Cord Damage from
Radiant Heat and Fire Exposure and
Full Scale Burn Tests of Television Sets
and Electronic Appliances
Donald J. Hoffmann
Safety Engineering Laboratories, Inc.
27803 College Park Drive
Warren, Michigan 48093
(586) 771-0660
selabs@aol.com
Return to Course Book Table of Contents
DR. DONALD J. HOFFMANN is the president of Safety Engineering Laboratories,
Inc., a firm specializing in the testing and evaluation of chemical, mechanical, and
electrical products and processes as well as the investigation and recreation of fire and
explosion incidents. Among other tasks, Dr. Hoffmann performs process safety management assessments and audits, develops protocols for testing and analyzing materials and products, and performs engineering analyses of fire and explosion incidents.
Dr. Hoffmann also serves as a member of the NFPA Technical Committee on Hazardous Chemicals, and is a member of a number of professional associations, including
ASTM, SFPE, IAAI, and AIChE.
Electrical Power Cord Damage from Radiant Heat and
Fire Exposure and Full Scale Burn Tests of Television
Sets and Electronic Appliances
Table of Contents
I. Electrical Power Cord Damage from Radiant Heat and Fire Exposure* ................................................ 21
A. Abstract .......................................................................................................................................... 21
B. Introduction ................................................................................................................................... 21
C. Background .................................................................................................................................... 21
D. Power Cords.................................................................................................................................... 23
E. Test Station ..................................................................................................................................... 23
F. Test Methodology ........................................................................................................................... 24
G. Test Data ......................................................................................................................................... 24
H. Discussion ...................................................................................................................................... 24
I. Summary ........................................................................................................................................ 26
J. Conclusions .................................................................................................................................... 26
K. Acknowledgments .......................................................................................................................... 26
References .............................................................................................................................................. 26
II. Full Scale Burn Tests of Television Sets and Electronic Appliances* ..................................................... 27
A. Abstract .......................................................................................................................................... 27
B. Introduction ................................................................................................................................... 28
C. Background .................................................................................................................................... 28
D. Test Facility, Burn Room, and Instrumentation .............................................................................. 29
E. Tests ................................................................................................................................................ 30
F. Discussion ...................................................................................................................................... 30
1. Fire performance of materials ................................................................................................. 30
2. Fire analysis of burn patterns .................................................................................................. 32
3. Television and appliance damage ............................................................................................ 32
G. Conclusions .................................................................................................................................... 33
References .............................................................................................................................................. 34
Part I: Electrical Power Cord Damage from Radiant Heat and Fire Exposure—Tables and Figures .................. 36
Part II: Full Scale Burn Tests of Television Sets and Electronic Appliances—Tables and Figures ...................... 43
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 19
Electrical Power Cord Damage from Radiant Heat and Fire Exposure
and Full Scale Burn Tests of Television Sets and Electronic Appliances
I. Electrical Power Cord Damage from Radiant Heat and Fire Exposure*
A. Abstract
Nine SPT-1 and SPT-2 type two conductor energized appliance power cords were exposed to radiant
heat and to flames in the presence and absence of combustible materials. The power cords consisted of integral
and nonintegral insulated multistranded 18 AWG copper conductors. The objectives of exposing these power
cords to radiant heat and flame are to: evaluate the performance of the power cords in fire environments, and
characterize the electrical activity and material damage sustained by the power cords. Data was recorded for
713 power cords tested under six different conditions. Not all of the power cords tested showed evidence of
electrical fault activity. However, each power cord exposed to a radiant heat flux of 40kW/m2 in the presence of
combustible material exhibited signs of electrical fault activity. Damage to the copper conductors varied from
localized fusing to complete severance. Power cords exposed to a radiant heat flux of 40kW/m2 in the absence
of combustibles did not always exhibit signs of electrical fault activity. Test data did not show any significant
correlations among types of power cord damage or electrical activity and fire conditions.
Keywords: appliance, power cords, electrical activity, arcing
B. Introduction
One of the methods utilized by fire investigators to investigate the cause of a fire is to examine all of the
possible ignition sources within an area of origin. Electronic devices and appliances such as televisions, VCRs,
radios, and compact disc players, are frequently found in areas of origin. As potential ignition sources are eliminated, appliances and appliance power cords are examined for signs of electrical damage. If electrically caused
damage to power cord conductors is identified, the associated appliance and its power cord can become the object
of intense examination. The formation of beads or balls of copper on one or more copper conductors of a power
cord is typically interpreted as evidence that electricity was supplied to the appliance when the fire occurred.
An analytical technique to determine whether electrically caused damage to conductors was the cause of a fire
or occurred as a result of the fire does not currently exist.
The objectives of the research reported here are to determine: (1) any differences in the power cord
performance based on manufacturer and on type of construction; (2) conditions under which power cord faults
caused by exposure to radiant heat and flame draw sufficient current to open a typical residential circuit breaker;
and (3) any significant difference in damage appearance of electrical conductors under different initiating events
that produced electrical faulting. Additional work is under way to examine the capability of and conditions under
which power cords can cause fires.
C. Background
The primary focus of fire investigations is to determine the cause of a fire. Included in the array of tools
and techniques that an investigator can use when determining the cause of a fire is the examination of electrical
* Previously published as: Hoffmann, J.M., Hoffmann, D.J., Kroll, E.C., Wallace, J.W., Kroll, M.J. Electrical power cord
damage from radiant heat and fire exposure. Fire Tech. 34(2001):129–42. Content published here with permission.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 21
conductors found in the fire scene. Evidence of faulting can be found on the electrical conductors in appliance
cords, branch circuit wiring, on electrical connections, panel boxes and the internal wiring of a wide variety of
electrical equipment and devices. When damage to conductors is found, the first determination to be made is
whether the observed damage is in the suspected area of the fire’s origin. Next, the observed damage to the conductors is classified as nonelectrical in nature (e.g., thermal melting, alloying, or mechanical damage); or electrical
in nature as caused by the undesired flow of electrical current between conductors or between a conductor and
ground.
Authors Etting,1 Beland,2 and Bright3 inter alia have described the differences in damage to electrical
conductors caused by fire, that is, thermal melting, alloying, and electrical faulting. A summary of the characteristics of these types of damage is contained in NFPA 921, Guide for Investigation of Fires and Explosions, and
in Reference 3. Typically the determination of whether conductor damage is electrically or thermally caused is
straightforward and causes little controversy among competent fire investigators. When damage to electrical
conductors is caused by electrical faulting, however, the determination of whether the fault caused the fire or
was caused by the fire is an entirely different matter.
Within the past 20 years, a number of investigators have proposed methodologies in an attempt to accurately distinguish between damage caused by faulting of electrical conductors by a fire, and damage caused
by faulting of electrical conductors that started a fire. For the most part, these methodologies have focused on
the chemical analysis of the fused copper in an attempt to relate the presence or absence of particular chemical
species dissolved in the copper.
The initial work in this area by MacCleary and Thaman4 is summarized in Reference 5. These researchers
utilized Auger Electron Spectroscopy capabilities of surface chemical analysis including Auger Electron Spectroscopy to measure oxygen concentration at various depths (from the surface) in copper beads produced by
electrical faults. (The reader is referred to references 13 and 14 for techniques, methods and capabilities of surface
chemical analysis including Auger Electron Spectroscopy.) Anderson6,7 applied Auger Electron Spectroscopy to
extend the analysis to carbon, chlorine, copper, calcium and zinc. The basic idea behind this “depth analysis”
theory is that if an electrical fault causes a fire, the fused copper beads found after the fire will contain gases absorbed from the nonfire environment when the metal was molten (i.e., when the bead was formed). In contrast, if
an electrical fault is caused by and during a fire, such as by charring the insulation and/or producing a conductive
path between conductors in a fire, the copper beads will have been formed in a fire combustion gas environment.
Chemical species present in the fire environment include carbon (carbon, carbon monoxide and dioxide), chlorine (hydrogen chloride), calcium (carbonate) and other elements not expected to be present in ambient pre
fire conditions.
Subsequent to the publication of Anderson’s findings, questions have arisen regarding the validity of
Auger analyses to definitively establish when a copper bead was formed. Several authors have published critiques
and direct challenges to Anderson’s postulates. Howitt,8 for example, points out that “the levels of gas solubility
in liquid copper [are] several orders of magnitude below the minimum amounts that one could possibly hope
to detect by Auger analysis.” He cites research that shows not only that the solubility of oxygen in molten copper
is extremely small but that oxygen is more soluble in solid copper at its melting point than it is in liquid copper
at its melting point. Howitt ascribes the high percentage of oxygen that Anderson finds during his analyses to
cupric oxide [sic] (Cu2O). In fact, it may well be that both cuprous and cupric oxides are present since both are
relatively stable even in a mildly reducing atmosphere and are readily formed in fires.
Henderson9 and Beland10 have analyzed data profiling the atomic weight percentage of carbon at various depths in copper beads. They analyzed and compared data from copper beads that were produced in a fire
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November 2003
(i.e., electrical fault caused by the fire) and for beads that caused the fire (i.e., electrical fault causes the fire). On
the basis of carbon depth profiles, neither author was able to differentiate between copper beads produced by an
electrical fault that caused (initiated) a fire and copper beads that were produced when a fire caused an electrical
fault to occur. They, as well as others, are also critical of Anderson’s work based on an apparent lack of known
and/or standards testing by Anderson. The authors of this paper have also analyzed unpublished data provided
by Anderson in litigations. We have been unable to reach the same conclusions as Anderson even when provided
with his analysis. The analysis of Auger spectroscopic data from copper beads found at fire scenes appears to be
an inconclusive method, at best, for determining whether or not the incident beads were formed during the fire
or at the onset of the fire. The results of microscopic examination of fire related damage in most instances can
not be related to the macroscopic behavior of fire.
Two other approaches to the use of electrical conductor damage during fire investigation has been presented by Delplace11 and by Gray.12 Gray investigated conductor damage caused by a fire and damage to conductors caused by an extreme current overload. Using a scanning electron microscope (“SEM”), Gray compared the
beads formed under these two conditions and reported that these two different fault conditions can produce
distinct patterns that can be differentiated by the SEM. No subsequent work on this method, however, has been
published. Delplace used arc damage on branch circuit wiring to track fire growth and spread. The analysis of
electrically caused damage to branch circuit wiring and appliance cords is an important investigative tool for
confirming or eliminating fire origin areas particularly when severing faults are noted.
D. Power Cords
The power cords used are typical of those used with radios, televisions, and other electronic equipment.
The multistranded copper conductors are insulated with polyvinyl chloride flexible plastic formulations. Cords from
different manufacturers may have contained slightly different amounts of plasticizers, fillers, pigments, and other
additives. To the extent such differences may have existed they were not quantified or evaluated in this testing.
The nine insulated copper conductor power cords are identified as: SEL01-I (SPT-2), SEL02-I (SPT-2),
SEL03-I (SPT-1), SEL04-I (SPT-2), SEL05-I (SPT-1), SEL06-I (SPT-2), SEL07-NI (SPT-2), SEL08-NI (SPT-2)
and SEL09-NI (SPT-2). Power cords suffixed with -I indicate integral or single jacket insulation and power cords
with a -NI indicate non-integral or double jacket insulation. SPT-1 and SPT-2 refer to the type of power cord as
defined in Article 400 of the National Electrical Code.
E. Test Station
A test station to expose different appliance (e.g.., television, clock radio) power cords to radiant heat
and direct flame impingement was constructed. Figure 1 is an illustration of the test station.
A single electrical circuit, protected by a single pole Type OP 15 AMP, 125 volt circuit breaker, was wired
to a duplex receptacle. The power cord that was being tested was plugged into one outlet. The other end of the
power cord was connected to a lamp containing a 15-watt light bulb. The second outlet in the receptacle also was
connected to a lamp also containing a 15-watt light bulb. When, or if, the power cord under test severed during
the test its associated lamp would extinguish. If damage to the test power cord caused the circuit breaker to trip
the other lamp also would extinguish. If the circuit breaker did not trip then this lamp would remain lit indicating
that the cord fault (i.e., arc) was of insufficient RMS current to open the circuit.
The RMS available fault current at 36 inches along the test power cord from the receptacle at the test station was determined to be approximately 300 amps. (The available fault current was determined by John Matthews
and Associates, electrical engineering consultants and Detroit Edison Company for the electrical utility servicing
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 23
the facility in which the tests were conducted.) For shorter distances from the receptacle, the RMS available fault
current would be slightly higher. In either case, the available RMS current easily exceeded the amount necessary
for instantaneous tripping of the Type OP circuit breaker.
The radiant energy and flame exposure test configurations were intended to simulate a typical environmental condition found at a fire scene where power cords are exposed to radiant energy and/or flames before, during and after flashover. A radiant heat exposure of 40kW/m2 was used to simulate flashover and postflashover.
While this is somewhat higher than the 20kW/m2 typically used to achieve flashover, the only difference in test
results that were noted when the radiant heat energy source was being evaluated was the time-to-fault. The higher
radiant energy value was chosen to reduce the time to fire involvement by the exposed cord or combustible surface. Flame exposure conditions were achieved by ignition of carpeting or hardwood flooring under a test cord
by radiant energy, or by applying a flame to the cord from a gas burner or wood crib.
F. Test Methodology
Six configurations used during the test are summarized in Table 1. Radiant energy was produced by a
cone shaped electric heating element mounted on a ceramic base. Heat flux from the cone was controlled by a
variable power source and calibrated to 40kW/m2 at the power cord surface using a Schmidt-Boelter water
cooled heat flux transducer.
Each test was videotaped and the cord damage cataloged and photographed after the test.
G. Test Data
The data from each test configuration were tabulated and are presented in Tables 2–5. The different types
of power cords, test configurations, types of activity, time to activity, and power cord integrity were compared to
determine if there was a correlation between (1) the damage to the power cord(s) and the simulated fire environments and (2) the frequency of activity with power cord type for comparative fire performance. The damaged
conductors from each test were examined independently by three experienced fire investigators and engineers.
The purpose of this examination was to compare the laboratory induced damage with that typically observed at
fire scenes, in artifacts collected at fire scenes and from damaged conductors produced in full scale room fire tests.
H. Discussion
Observations during power cord testing established that during some tests (1) no electrical activity
occurred (i.e., no faulting of the energized power cord), (2) a fault in the cord occurred sufficient in magnitude
to interrupt the test light circuit but not sufficient in magnitude to trip the circuit breaker, and (3) a fault in the
cord occurred sufficient in magnitude to interrupt the circuit of the test light and trip the circuit breaker. The
nonoccurrence or occurrence of electrical activity in power cord electrical activity for each test configuration is
summarized in Table 2.
In Test Series A, each power cord was suspended in air and subjected to a heat flux of 40kW/m2 at the
cord’s surface. Due to the size of the cone and the configuration of the power cord, the length of cord surface
exposed was approximately six to eight inches. In this test configuration, 58 percent of the power cords did not
exhibit electrical activity and circuit integrity was maintained during exposure to the radiant energy for 15
minutes. Of the 76 cords that did exhibit electrical activity in this test configuration, the fault in 45 cords was
sufficient to trip the circuit breaker. Thirty-nine cords severed completely during the test. Twenty-three of the
severed cords tripped the circuit breaker and 18 cords interrupted only the test lamp circuit.
In Test Series B, fewer power cords exhibited electrical activity when radiant heat (i.e., 40kW/m2) was
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Fire and Casualty ❖
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directed on the surface of the power cord at a 45 degree angle. Due to the size of the cone and the configuration
of the power cord, the length of cord exposed was two to three inches. In this test series, 25 percent of the cords
exhibited electrical activity. Three cords tripped the circuit breaker. Fewer power cords severed (i.e., 11 percent)
when compared to the horizontal orientation tests (i.e., 19 percent) in Test Series A. Of the 12 severed power cords,
three of the severed cords faulted with sufficient magnitude to trip the circuit breaker.
More power cords exhibited electrical activity when exposed to direct flame in Test Series C than in
the radiant heat Test Series A and B. Thirteen of the 77 power cords that exhibited electrical activity interrupted
only the test lamp circuit. Twelve of the 13 power cords had nonintegral or double jacket insulation. Faults in the
remaining 64 cords were sufficient to trip the circuit breaker. Flame impingement did not increase the tendency
of the different power cord types to sever when compared with radiant heat exposure. The time to electricity
activity, however, was significantly reduced. All power cord electrical activity occurred within three minutes of
flame exposure.
In Test Series D and E, each power cord was tested laying on carpet and wood substrates. The 40kW/m2
radiant heat source was directed at the power cord and substrate. Integral power cords exhibited electrical activity
within four minutes from the start of the test while the nonintegral power cords exhibited activity between 4.5 and
6.5 minutes. The nonintegral power cords exhibited a greater tendency to sever than the integral power cords. A
majority (i.e., 63 percent Test Series D and 71 percent of Test Series E) of power cord faults tripped the circuit
breaker.
In Test Series F, power cords were suspended over and exposed to a wood crib fire. The wood crib was
ignited using a kerosene saturated cloth. The fire from the wood crib eventually involved the power cord insulation. All power cords in Test Series F exhibited electrical activity and 16 of the 18 cords tested tripped the circuit
breaker.
Data from the power cord tests show that, regardless of power cord type, exposure to the same heat flux
or flame conditions produces similar results. Different test results from the same power cord under the same conditions indicates that the current, associated with the fault, has variable magnitude. There is, however, a greater tendency for the circuit breaker to trip when an energized power cord is exposed to flame than to radiant energy only.
Damage to the copper conductors caused by electrical activity in each Test Series was documented. The
physical appearance of the damage did not correlate with a single test variable or power cord type. The observed
electrical event was not always instantaneous. Instances of continuous arcing were observed but the damage associated with single versus multiple events could not always be differentiated. Examination of the power cords
after each Test Series shows that, in general, severed cords typically have beads of copper on each end of the
severed conductor. Conductors that did not sever had localized fusing or melting at the interface between conductors. Multiple occurrences of arcing along the conductors was not uncommon. There was no discernable
pattern of electrical fault damage that allows a determination of what fire conditions are associated with the observed damage. Figures 2–6 are photographs representative of the damage sustained by the copper conductors
of power cords that exhibited electrical activity.
During the course of the tests and following the completion of the tests, the conductors of the power
cords were examined by experienced fire scene and fire artifact investigators. The types of damage observed were:
multiple areas of arcing evidence along a cord (Figure 2), severing of a conductor(s) with distinct or minimal
beading (Figure 3), fusing of some or all of the strands within a conductor (Figure 4), partial severing of the
power cord conductors with and without beading (Figure 5), pitting of conductors from arcing, and deposits of
copper that were ejected during the arc onto conductors in the vicinity of the faults (Figure 6). The types of damage to the multistranded copper conductors induced by fire in these laboratory tests were indistinguishable from
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 25
those observed from fire scenes. Full scale room fire tests conducted by Safety Engineering Laboratories involving
electrical appliances such as televisions, radios, stereos, refrigerators, and cordless telephones have also produced
damage to the appliance power cords that is not distinguishable from the damage produced in the laboratory
tests. (Unpublished results from Safety Engineering Laboratories, Inc. SEL conducted a series of full scale tests
for the Consumer Electronics Association to provide instructional materials for assisting in evaluating fire scenes
involving small appliances and electronic devices. Powered appliances were used in some of these tests.)
I.
Summary
Some test data indicate slight variation in performance among the different power cords in the radiant
heat exposure tests. A statistical analysis of the results, however, indicates that these differences are not significant
enough to provide a basis for information about the characteristics of the exposure fire. Similarly, nonintegral
power cords do not perform significantly different from the conventional single extrusion cords with the exception of time: the nonintegral cords maintain electrical integrity longer when exposed to radiant energy or flame
than integral or conventional cords. Both integral and nonintegral cords, however, exhibit electrical activity 100
percent of the time when exposed to a fire from a combustible surface (e.g., wood and carpet). Damage ranging
from conductor severing to strand fusing cannot be used as a determinant of whether or not the observed damage
was sufficient to trip a circuit breaker. A severed conductor is not more likely to trip a circuit breaker than other
types of observed electrically caused damage.
J. Conclusions
Based on the Test Series, the following conclusions were reached regarding the exposure of electrical
power cords to radiant heat and flame:
• Energized power cords do not always produce evidence of electrical faults when exposed to radiant heat sources that char or ignite the cord insulation. Energized power cords in contact with
combustible surfaces ignited by radiant heat always produced evidence of electrical faults.
• The physical appearance of electrical faults in power cords produced when energized power cords
are exposed to radiant heat or flame does not depend upon the:
• Magnitude or duration of the fault current (i.e., trips circuit breaker),
• The conditions of fire exposure,
• The type of insulating material and construction of a electrical power cord.
• Electrically caused damage to power cord conductors produced under controlled laboratory fire
conditions does not differ from that damaged observed under field fire conditions.
K. Acknowledgments
The authors thank the Consumer Electronics Association (“CEA”) and Safety Engineering Laboratories,
Inc. (“SEL”), for financial support in conducting this research. We are also indebted to CEA member companies
for their material support and thoughtful suggestions. We would also like to recognize Dan Kugler and Roger
Harrison of SEL for their efforts in organizing and conducting many of the tests.
References
1. Etting, B.V. Electrical wiring in building fires. Fire Technology 14(4)(Nov. 1978):317.
2. Beland, B. Examination of electrical conductors following a fire. Fire Tech. 16(4)(Nov. 1980):252.
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Fire and Casualty ❖
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3. National Bureau of Standards, Fire Investigation Handbook, PE 81-113482, eds. Bright, R.G., Norah, J., U.S.
Department of Commerce, 1980.
4. MacCleary, R.C., Thaman, R.N. “Methods for Use in Fire Investigation,” United States Patent, Patent Number 4,182,959, (1980).
5. Interview: Did the short cause the fire or did the fire cause the short. Fire & Arson Investigator
30(1)(1979):57.
6. Anderson, R. N. Surface analysis of electrical arc residues in fire investigation. J. Forensic Sci.
34(3)(1989):633.
7. Anderson, R.N. Which came first the arcing or the fire, a review of Auger analysis of electrical arc residues.
Fire and Arson Investigator, Mar.1996, p. 38.
8. Howitt, D.G. The surface analysis of copper arc beads–A critical review. J. Forensic Sci. 42(4)(1997):608.
9. Henderson, R., Manning, C., Barnhill, S. Questions concerning the use of carbon content to identify “cause”
vs. “result” beads in fire investigations. Fire & Arson Investigator 48(3)(Mar, 1998):26.
10. Beland, B. Examination of arc beads. Fire & Arson Investigator 44(4)(June 1994):20.
11. Delplace, M., Vos, E. Electric short circuits help the investigator determine where the fire started. Fire Tech.
19(3)(1983):185.
12. Gray, D. A., Drysdale, D.D., Lewis, F. A. S. Identification of electrical sources of ignition in fires. Fire Safety J.
6(1983):147.
13. Grogan, A., Rice, S., Davidson, M. “Surface chemical analysis.” In ASM Handbook, vol. 10, 445 (1992).
14. Grant, T. J. “Methods for quantitative analysis in XPS and AES” In Surface and Interface Analysis, vol. 14,
271(1988).
II. Full Scale Burn Tests of Television Sets and Electronic Appliances*
A. Abstract
Ten full-scale burn tests of television sets and electronic appliances were performed to (1) demonstrate
the ignition propensity and fire performance characteristics of materials used in the construction of television
sets marketed in the United States and to compare these to the fire performance of television sets marketed in
Europe; (2) document the damage to television sets when exposed to nearby burning materials; (3) evaluate
and compare the damage to television sets when subjected to different size, duration and types of fires; (4)
evaluate fire damage to television sets and electronic appliances when exposed to postflashover conditions; and
(5) evaluate electrical damage caused to components of electronic appliances while they are powered and subjected to exposure fires.
Ignitability tests showed that television sets constructed with cabinets made of V-0 rated plastics (for
the U.S. market) will not ignite and propagate a flame under the test conditions. Television sets made of HB rated
plastics (for the European market) will ignite and propagate a flame under the same test conditions and the
television set will be consumed in the ensuing fire. The UL 94 tests do not provide rate of heat release data;
however, calorimetry test data showed that the rate of heat release and the burning of the electronic appliances
and television sets were in part dependent on the size of the exposure fire.
* Previously published as: Hoffmann, J.M., Hoffmann, D.J., Kroll, E.C. Kroll, M.J. (2003). Full scale burn tests of television sets and electronic appliances. Fire Tech. 39:207–224. Content published here with permission.
Electrical Power Cord Damage and Full Scale Burn Tests
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Examination of the television sets and electronic appliances after the burn tests showed that the severity of damage and type of damage varied significantly. Electrical fault activity was noted to have occurred both
exterior and interior to the powered television sets as well as other powered electronic appliances. In all cases, the
fire source was external to the appliance.
Post fire examination after the flashover fires showed that fire pattern analysis and burn damage are not
necessarily indicative of the area of origin or cause and can be misleading to even “experienced” fire investigators.
B. Introduction
The investigation of a residential fire scene quite often will focus on the omnipresent television set—possibly because of its size, fuel load, and electrical energy that is involved. The question becomes whether or not it
can be determined by inspection of the damage to the television set whether the fire originated at the television set
or whether the damage was sustained by the television exposed to an external fire. With these interests and several
other specific objectives in mind, Safety Engineering Laboratories (“SEL”) conducted a series of full scale burn
tests for the Aftermarket Evaluation Working Group of the Consumer Electronic Association’s Product Safety and
Compliance Engineering Committee. The tests were conducted at SEL’s full scale burn facility in Yale, Michigan.
Sixteen commercially available television sets and an assortment of electronic appliances, including
large and small radios, answering machines and cordless telephones, were exposed to external fires. The size of
the external fire sources ranged from small isopropyl alcohol pool fires to upholstered and wooden furniture fires.
Preliminary tests were conducted to quantify the size of the ignition source and duration of the exposure fire.
The test objectives were to: (1) demonstrate the ignition propensity and fire performance characteristics
of materials used in the construction of television sets marketed in the United States and to compare these to the
fire performance of television sets marketed in Europe; (2) document the damage to television sets when exposed
to nearby burning materials; (3) evaluate and compare the damage to television sets when subjected to different
size, duration and types of fires; (4) evaluate fire damage to television sets and electronic appliances when exposed
to postflashover conditions; and (5) evaluate electrical damage caused to components of electronic appliances
while they are powered and subjected to exposure fires. Specifically, the fire performance of a variety of television
sets in both pre- and postflashover fire environments was tested and compared. The damage sustained by the
television sets and electronic appliances when subjected to known external (exposure) fires was characterized.
The damage sustained by the plastic enclosure, internal components and power cords of operating televisions
was compared to damage sustained by televisions that were not powered. The response of circuit overcurrent
protection devices associated with energized televisions and electronic appliances in fire environments was integral in this study. The results of the testing and the damage to the television and appliances were used to evaluate some popular notions about how the picture tube assembly and other major components behave in fires.
C. Background
The first standard for television sets was introduced by Underwriters’ Laboratories (“UL”) in 1957 under
UL 492, Standard for Radio and Television Receiving Appliances, Ninth Edition (previously the Standard for
Power-Operated Radio Receiving Appliances).1 The first requirement for a specific fire performance rating for
enclosure materials was effected on July 1, 1974, requiring that polymeric materials used in cabinet enclosures
meet the HB rating.2 The fire performance requirement was subsequently increased to a V-2 rating in 1975, a V-1
rating in 1977, and a V-0 rating for major parts of an enclosure in 1978.3 The 15th edition of the standard, renumbered UL 1410 in 1976 and currently titled Standard for Television Receivers and High-Voltage Video Products,
continues to require a V-0 rating for major parts of the television enclosure.4
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The introduction of these fire performance requirements coincided with increased interest from the U.S.
Consumer Product Safety Commission (“CPSC”) in the development of a standard for television receiver safety.
In 1975, the CPSC issued a notice in the Federal Register to begin the development process of a consumer product
safety standard addressing the hazards (i.e., fire, electric shock, explosion, and mechanical hazards) of television
receivers.5 As the UL standards became more stringent, the CPSC continued to monitor the perceived hazards
involving television sets. According to a 1979 statistical analysis performed by the CPSC, from 1975 to 1977 there
were approximately 34.4 fires per million color televisions with cabinets of UL 94 HB (“HB”) plastic (532 fires
total) and 4.6 fires per million color televisions with cabinets of V-0 plastic (46 fires total) manufactured between
1970 and 1977.6 While some of this difference can be attributed to an overall decrease in the number of fires and a
decrease in the use of HB plastic, the CPSC analyst states that, “…even if the data are restricted to 1975–1977 fire
incidents in 1975–1977 produced sets, the relative risk of fires in TV sets with HB plastic is four times higher
than the risk with V-0 cabinets.” Using other data from this time period (i.e., the 1970s), there were an estimated
10,000 television fires annually.7 Criticisms of this statistic included the identification of smoke, odors, and
other failures that did not contribute to the destruction of any property outside of the set as a fire incident.8
Currently, it is estimated that there are approximately 2,000 television, radio, VCR, and phonograph fires
annually in U.S. homes.9 Of these, the CPSC estimates that half can be attributed to televisions.10 Thus, in the last
five years for which data is available (i.e., 1994–1998), it is estimated that there have been 364,540 residential
fires annually, and an estimated 940, or 0.25 percent, of these fires have been identified as related to televisions.
According to Neilsen Media, there are more than 102 million “TV homes” in the U.S.,11 and of these homes, approximately 35 percent have two television sets in their homes and 41 percent have three or more.12 This means
that there are more than 221 million television sets in U.S. households. Of these 221 million television sets, an
estimated 940 are alleged to be involved in fires each year, or 2.4 fires per million television sets. The trend in fires
involving television sets and other electronic appliances is illustrated in Figure 1. From this graph, the decline
in the number of fires alleged to involve television sets and/or electronic appliances is apparent.
The widespread use of television sets and other consumer electronic appliances in residential homes
caused these products to be identified as potential causes and/or areas of origin during a fire scene investigation.
For television sets, some experts have tried to correlate the position of the electron gun, the damage to the shadow
mask, and the position of the tube neck with the origin of the fire being inside the television set or outside the
television set.13 In other known cases, opinions as to the television being the cause of the fire has been made based
solely on the evidence of internal electrical faults identified inside the television set and “hot spots” noted on the
television sets’ circuit boards, usually around the flyback transformer. There are no test data or other articles to
support or validate these observations and opinions. Other household electronic appliances have been identified
as the cause of a fire based solely on the evidence of electrical faulting occurring in the appliance, on its line cord
or at the blades to its plug and/or based on internal hot spots noted on the appliance’s circuit board. Exposure fire
testing of energized line cords has shown that electrical faults occur when the insulation of the energized line cord
is compromised due to exposure to heat and/or fire.14 Although some burn testing of televisions or consumer
electronic appliances and their damages has been done,15,16,17 none has been reported in refereed literature.
Testing of consumer electronic appliances in full scale fire exposures is the subject of this article.
D. Test Facility, Burn Room, and Instrumentation
Five of the burn tests were performed in SEL’s standard burn room (12'×8'×8'), which is fitted with an
exhaust collection hood and calorimetric measuring system. The size and construction of the burn room and the
configuration of the duct and associated instrumentation is based on applicable portions of ISO 9705 Fire Tests—
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 29
Full Scale Room Test for Surface Products.18 The hood exhaust system and instrumentation were calibrated with
propane before and after the tests conducted in the burn room.
K-Type thermocouples (“TCs”) were used to monitor the temperature inside the burn room and inside
the exhaust collection duct. Gas sampling probes, located in the duct, continuously sampled and monitored oxygen, carbon monoxide and carbon dioxide concentrations in the combustion gas collected from the burn room.
After each burn test, the television and other electronic appliances were photographed in place then
removed from the burn room. All television sets and electronic appliances were examined by uncovering layers
of debris to record damage patterns and the appearance of individual components such as fuses, transformers,
capacitors, the picture tube assembly, and circuit boards.
E. Tests
Table 1 is a summary of the television and electronic appliance ignition and burn tests. Table 1 includes
the rating of the cabinet plastic classification (V-0 or HB), the television screen size, the number and kind of electronic appliance(s) used during the test, the external fire source, combustible articles present, whether the television and appliances were energized or not, and the total time of the test from ignition to extinguishing the fire.
As shown in Table 1, each burn test was performed two times: once using televisions and electronic
appliances that were not energized (Tests 1A, 2A, 3A, 4A, 5A); the second time using energized and operating
televisions and electronic appliances (Tests 1B, 2B, 3B, 4B, 5B). For Tests 1A-3A and 1B-3B, the television sets
were placed inside a wood entertainment center. For Tests 4A and 4B, the television set was placed on a wood stand
next to an upholstered chair. During Tests 5A and 5B, multiple television sets and electronic appliances were
placed on wood stands and on the floor in a burn room containing an upholstered chair and area rug. In Test
5B, the energized appliances were serviced on independent circuits and protected by 15-amp circuit breakers.
Circuit integrity and circuit breaker activation was monitored.
Isopropyl alcohol (“IPA”) in a two-inch-diameter aluminum dish was used as the external fire source for
the television sets in Ignition Tests 1 and 2 and Tests 3A and 3B or was used to ignite an electrical appliance (telephone or radio) adjacent to the television set in Tests 1A, 1B, 2A and 2B. IPA, as an ignition source, is easily duplicated and has been used in industry-sponsored tests as an ignition source.15 In Tests 4A, 4B, 5A and 5B, sheets of
newspaper under the cushion and on the floor in front of the upholstered chair were the first materials ignited.
For Tests 1–4, the fire was allowed to continue until just before flashover conditions were attained or
when a steady, long term fire growth was continuing such that all combustible material might be consumed, at
which time the fire was extinguished. In Tests 5A and 5B, the fire was not extinguished until four minutes past
flashover. It was determined that flashover conditions in the room were achieved when crumpled newspaper, used
as flashover indicators, on the floor ignited and/or the measured temperature inside the room reached 1200°F.
F. Discussion
1. Fire performance of materials
The fire performance of the wood entertainment center and television cabinet materials were determined
using the ASTM 1354 standard method for Heat and Visible Smoke Release Rates for Materials and Products using
Oxygen Consumption Calorimeter19 or as it is more commonly referred to as cone calorimetry. Cone calorimetry is
used to determine the ignitability, heat release rates, mass loss rates, effective heat of combustion, and visible
smoke development of materials and products. A sample of the television cabinet from a television set and the
entertainment center were cone tested at 20 kW/m2 and 40 kW/m2. The 20 kW/m2 incident heat flux is generally
30
❖
Fire and Casualty ❖
November 2003
accepted as the heat flux at flashover conditions; 40 kW/m2 incident heat flux is a representative value of the heat
flux between adjacent items in fire environments. The cone calorimetry data from the television set and the entertainment center are compared to literature values for common polymeric materials at 20 kW/m2 and 40 kW/m2.20
Tables 2 and 3 summarize and compare the cone data of the entertainment center, television cabinet, common
flame retarded and non flame retarded polymeric materials at heat fluxes of 20 kW/m2 and 40 kW/m2, respectively.
The composition of the plastic cabinet of a V-0 rated television was determined using Fourier Transform
Infrared Spectroscopy (“FTIR”) and Energy Dispersive X-ray Spectroscopy (“EDS”). The television cabinet is a
polystyrene based polymer with a calcium based filler and treated with flame retardants that contain bromine and
antimony. The results of the cone testing of the television cabinet (averaged more than three determinations for
samples from two different television cabinets) show that its fire performance properties are comparable to a wide
range of fire retarded plastics and some alloys of non fire retarded plastics. The V-0 television cabinet is below the
average rate of heat release for the materials listed and about at the median at both 20 kW/m2 and 40 kW/m2.
The plastic cabinet of the European television set was analyzed by FTIR and EDS. The cabinet is composed primarily of polystyrene. Minor aluminum was detected by EDS. The fire performance of the cabinet would
be similar to a non-fire-retarded polystyrene that has a considerably higher peak heat release (1100 kW/m2 at
40 kW/m2 incident flux) than the U.S. manufactured V-0 cabinet (230 kW/m2 at 40 kW/m2 incident flux).
The plastic cabinet of the V-0 television set (Ignition Tests, Test 3A) ignited by 5 ml IPA in a dish did not
propagate combustion and self-extinguished after the IPA was consumed. Flame spread (if any) on the side of the
plastic cabinet was limited to the area directly above the ignition source. In contrast, the plastic cabinet of the
HB television set, when ignited by the same ignition source, burned readily with rapid flame spread. The plastic
cabinet and combustible components of the HB television were mostly consumed during the course of the fire.
A second ignition test was performed on a V-0 television set using a larger exposure fire of IPA and a plastic
telephone as the exposure fire. The television set showed limited damage, did not propagate a flame away from
the exposure fire and self extinguished after the IPA and telephone plastic were consumed.
The full scale rate of heat release (“RHR”) was determined by oxygen consumption calorimetry for four
V-0 television sets and one HB television set placed in wood entertainment centers. The ignition source in all cases
was 5 ml of IPA. The placement of the ignition source varied dependent on the test. For all V-0 television tests, one
or two plastic electronic appliances were placed adjacent to the television cabinet and were ignited by the IPA.
The HB television cabinet was ignited by IPA. Rate of heat release data is summarized in Figure 2. The initial peak
rate of heat release was 455 kW for the HB television; the average initial peak rate of heat release for the four V-0
televisions and appliances next to the television was 302 kW.
The fire performance of V-0 television sets was found to be a function of (1) the size of the initial exposure fire, that is, quantity and size of plastic electronic appliances ignited next to television; (2) the duration of the
exposure to the external fire; and (3) the degree of involvement of the entertainment centers. Damage to the
plastic cabinet of the V-0 television set was limited and there was no propagating fire when exposed directly to
the isopropyl alcohol exposure fire. When a plastic electronic appliance was ignited next to a V-0 television, the
plastic was consumed only where directly exposed to the larger exposure fire. However, flame spread across the
plastic cabinet to regions away from the burning electronic appliance was due to progression of fire across the
burning entertainment center vinyl covered particle board construction.
The fire performance and damage to the television sets were also found to be dependent on the duration
of exposure to the external fire. For example, the television sets in Test 4A and 4B, exposed to the burning of the
upholstered chair for three to four minutes, exhibited less damage than the television set adjacent to the burning
electronic appliance in Test 2.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 31
2. Fire analysis of burn patterns
One objective of the fire tests was to determine if burn patterns in the room were consistent with the origin
or location of the external fire. It was found that the damage to the entertainment centers, the electronic appliances,
and the plastic enclosures of the television sets, and the burn patterns on the gypsum wall in the burn room were
consistent with the size, duration, and location of the initial exposure fire. The post fire analysis showed that asymmetric fire patterns and heat damage was consistent with the location of the exposure fire for all but one preflashover exposure fire test. Test 1B showed a “V” pattern emanating from the floor behind the entertainment center
and below the location of the television. On the basis of this “V” pattern and the damage to the combustible materials nearby, the fire origin could be interpreted to be located on or near the floor behind the entertainment center
when the fire origin was to the left and along side the television inside the entertainment center. Instead, the “V”
pattern was caused by the burning, melting and dripping of the plastic electronic appliance next to the television.
Analysis of the burn patterns from both postflashover tests (Test 5A and 5B) showed that burn patterns
could be generated that were not indicative of the area of origin of the fire. For example Test 5B showed two “V”
patterns, one along the wall to the left, and one on the wall behind and to the right of the upholstered chair used as
the exposure fire. These “V” patterns originated from a burning radio located on the floor at that location (Figure
3), and a burning table stand and electronic appliances to the right of the chair (Figure 4). Other burn patterns
in the flashover tests showed similar misleading patterns from asymmetric burning of a television set with the
most damage on the side away from the origin of the fire to patterns on the gypsum walls indicating a “V” pattern
pointing to a television stand and associated electronics. There were some patterns that were indicative of the
fire originating in the chair, such as asymmetric burning of one side of a television stand next to the chair.
3. Television and appliance damage
Examination of the television sets and electronic appliances after the tests was done to determine the
extent of damage. The examination of the televisions included noting the damage to the picture tube glass, the
condition of the shadow mask, the location of the electron gun and yoke assembly, damage to internal components
and noting evidence of electrical faulting. Examination of the other electronic appliances included differential
damage hot spots and electrical activity.
The response of the television picture tube in the exposure fires varied. In the preflashover burn tests, the
picture tube cracked and glass fell in front and/or behind in no descriptive pattern as to origin or cause of the
fire. In Test 2B, the picture tube of the HB television picture tube imploded prior to flashover conditions in the
room. This implosion caused glass tube fragments to be expelled away from the set at a maximum distance of
fifteen feet. During the postflashover tests, the television picture tubes typically imploded. In Test 5A, three out
of four television sets were heard to implode; in Test 5B, all four television set picture tubes imploded.
The condition of the shadow mask of each picture tube was examined and compared to the mode of
failure of the picture tube. When the mode of failure of the picture tube was cracking, the shadow masks showed
varying degrees of damage from none and still in place (Tests 1A, 1B and 2A) to the shadow mask being shredded
and imbedded into the remaining fused plastic of the television set (Test 2B). When the mode of failure of the
picture tube was implosion from an exposure fire next to the television set (Test 3A), the shadow mask was
shredded and concave. When the mode of failure was implosion during or after flashover (Tests 5A and 5B)
and/or failure during flashover, but possibly not by implosion, then the damage to the shadow masks varied
from shredded, deformed, and damaged concavely (into the television set remains) and convexly (away from
the television set remains) to minimal damage and still in place.
The post fire location of the electron gun/yoke assembly from each television set was noted after each
32
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Fire and Casualty ❖
November 2003
burn test. The position of the electron gun/yoke assembly varied from directly below its location in the television
set fused into the remaining plastic to behind or beside the television set. No correlation could be made on the
position of the electron gun assembly and the type of exposure fire experienced by the television set.
During the B series tests, the television sets and electronic appliances were energized and the branch circuits, which supplied power to the appliances, were monitored. When the fire was ignited next to the television
set and involved the telephone and radios, the circuit breakers protecting those items tripped (Tests 1B and 2B).
When the fire involved the upholstered furniture next to the television set and radio and neither appliance or its
associated power cord was involved in the fire, the circuit breaker did not trip and power remained on to each appliance (Test 4B). When the fire was allowed to progress to flashover, all but two circuit breakers that had an appliance plugged into its receptacle tripped after flashover. Both of the circuit breakers that did not trip had two
electrical appliances plugged into their respective receptacles. Electrical faulting was noted on one of the appliances to each receptacle drawing insufficient current to trip the breaker. Similar results, that is, electrical faulting
in exposure fires with insufficient current draw to trip the breaker, were noted in tests where line cords were
subjected to an exposure fire.14 Nonenergized melting of copper conductors inside the television and/or appliance was also documented.
The examination of the electrical faults that occurred to the televisions and electronic appliances was
documented. A majority of the faults noted occurred on the line cord to the appliance or television. However, in
two instances, one television and one radio, the electrical fault occurred inside the cabinet housing the electrical
components. Figure 5 shows electrical activity on the stranded conductors inside the television from Test 2B.
Figure 6 shows electrical activity at the transformer for a radio used in Test 5B. The electrical activity damage
noted on the line cords was consistent with the damage previously noted.14 The faults on the line cords occurred
at different locations from the crimped connector for the plug blades to the entrance and/or plug into the appliance and/or television. A typical line cord fault is shown in Figure 7. Electrical faulting occurred at the receptacle
for two appliances in Test 5B; that electrical faulting produced a severing arc that severed the plug blades in the
receptacle (Figure 8).
The circuit board inside the electronic appliances showed varying levels of damage based on the exposure fire. X-rays of the fire damaged appliances and television remains confirmed that varying levels of damage
occurred to the circuit board. The television sets suffered fire damage burn patterns that left the main circuit board
undamaged by heat (Figure 9), caused localized damage to the main circuit board (Figure 10) to severe fire and
heat damage to the main circuit board of the television (Figure 11). Damage to the electronic appliances from the
postflashover burn tests (Tests 5A and 5B) was considerable with severe fire damage to the appliances and their
circuit boards. The damage to the appliances’ circuit boards varied from localized extreme heat damage to uniform damage. Damage to the circuit board was not indicative of a cause of the fire; however, the damage was
consistent with the extent of burning or duration of exposure.
The condition of the fuse inside each television set was examined after fire exposure. The results showed
that some of the fuses remained intact and showed continuity after the burn tests; however, in other televisions, the
fuse element had opened. Examination of the mode of failure of the fuses, that is, by heat from the fire or overcurrent protection is the subject of another study in progress.
G. Conclusions
Fire tests comparing the U.S. marketed V-0 plastic cabinet televisions with European HB plastic cabinet
televisions clearly show the improved fire performance of the V-0 rated fire retarded products. Modern U.S.
televisions are resistant to small ignition sources both external and internal to the television cabinet. The small
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 33
ignition source tests of V-0 cabinet televisions show that these appliances will self extinguish when the ignition
source is removed and, in general, do not produce a self-propagating fire.
The ignition tests and the tests in which V-0 and HB television cabinets were exposed to moderate exterior exposure fires demonstrate the differences of the V-0 cabinet to resist attack by exterior fire ignition sources
compared to the European HB rated cabinets. Using the same size and quantity of IPA (i.e., the same ignition
source), the U.S. marketed V-0 cabinets did not have significant flame spread away from the ignition source. These
cabinets did not produce a self-propagating fire and self extinguished after the exposure fire fuel was consumed.
The European HB television set ignited easily, developed into a self-propagating fire, burned readily and caused
the fire to grow to flashover conditions prior to extinguishment.
Oxygen consumption calorimetry of the television sets, electronic appliances and a laminated wood
particle board entertainment center showed: (1) the HB European television had an initial peak rate of heat release
of 455 kW with no other electronic appliances involved and caused the room to approach flashover conditions
prior to extinguishment, and (2) the V-0 constructed U.S. television set had an initial peak heat release (averaged)
of 302 kW including the electronic appliance initially ignited. The fire growth was stabilized and/or slowly involved the wood cabinet and approached flashover condition prior to being extinguished. These tests clearly show
the importance of total fuel configuration in developing fires. This is especially true when high rate of heat release appliances are part of the fuel package.
The burn tests show that, in general, preflashover fire generated patterns could be used to determine the
area of origin of the fire. In one case, however, melting, dripping and burning plastic caused drop down to generate an origin like burn pattern away from the actual origin. Postflashover fire generated patterns were difficult to
interpret with respect to determining the origin. Localized patterns on the television and appliances varied from
minimal to uniform damage to localized hot spots. The room burns produced patterns that were both consistent
with the origin as well as burn patterns and “V” patterns that were inconsistent with the origin. These tests again
demonstrate that caution must be used when evaluating burn patterns alone to determine the origin of a fire.
This is particularly true for compartment fires that have progressed to flashover conditions.
The condition of the television and electronic appliances after the burn tests, such as the damage to the
television picture tube, location of picture tube glass, location of the electron gun/ yoke assembly, damage and
position of the shadow mask and damage/damage patterns to circuit boards, showed no correlation with the cause
of the fire. Electrical faulting was noted on energized conductors of the line cords, inside the televisions or electronic appliances and at the plug blade assemblies. In each of these cases, the damage was caused by the fire and
not a cause of the fire. Melting of nonenergized conductors was also noted in the televisions and electronic appliances that was a result of the thermal effects of the fire alone.
References
1. Underwriters Laboratories, Inc. UL 492: Standards for Radio and Television Receiving Appliances, Ninth
Edition, Northbrook, IL: UL, 1957.
2. Hoffman, S.D. and Duda, D.O. A History of: the Development of the Proposed Federal Mandatory Safety Standard for Television Receivers. A Voluntary Effort (for the U.S. Consumer Product Safety Commission), Northbrook, IL: Underwriters Laboratories, Inc., 1980.
3. Underwriters Laboratories, Inc. Revision pages for Standard for Television Receivers and Video Products. UL
1410, Thirteenth Edition, Northbrook, IL: UL, June 13 1978.
4. Underwriters Laboratories, Inc. UL 1410: Standard for Television Receivers and High Voltage Video Products,
Fifteenth Edition, Northbrook, IL: UL, November 12 1998.
34
❖
Fire and Casualty ❖
November 2003
5. 40 FR 8592, Federal Register, February 28 1975.
6. Harwood, B. Fire Incidence in Television Receivers, Washington, DC: U.S. Consumer Product Safety Commission (“CPSC”), June 26 1979.
7. CPSC, Fact Sheet No. 11: TV Fire and Shock Hazards, Washington, DC: CPSC, May 1975.
8. Mennie, D., “Troubleshooting” color tv: more smoke than fire may emanate from widely publicized consumer surveys and hazard data, IEEE Spectrum, June 1975, 57–62.
9. Rohr, K.D., The U.S. Home Product Report (Appliances and Equipment Involved in Fires), Quincy, MA:
National Fire Protection Association, April 2000.
10. Mah, J., 1998 Residential Fire Loss Estimates, Washington, DC: CPSC, 2001.
11. Nielsen Media Research, “FAQs—About Universe Estimates,” retrieved on November 20, 2001 from
http://www.neilsonmedia.com.
12. TV-Turnoff Network, “Facts and Figures about our TV Habit,” retrieved on November 20, 2001 from
http://www.tvturnoff.org.
13. Yearance, R.A., Electrical Fire Analysis, Second Edition, Springfield, IL: Charles C. Thomas, 1995.
14. Hoffmann, J.M., Hoffmann, D. J., Kroll, E. C., Wallace, J.W., Kroll, M.K. Electrical power cord damage from
radiant heat and fire exposure. Fire Tech. 37(2001):129–41.
15. Troitzsch, J. H. Fire Safety of TV-sets and PC-monitors, retrieved on July 30, 2002 from
http://www.ebfrip.org/statements/Troitzschfinalreport.pdf, 1998.
16. Simonson, M., Blomqvist, P., Boldizar, A., Moller, K., Rosell, L., Tullin, C., Stripple, H., Sundqvist, J. O., Fire-LCA
TV Case Study, SP Report 2000: 13, Borås, Sweden: SP Swedish National Testing and Research Institute, 2000.
17. Hietaniemi, J., Mangs, J., Hakkarainen, T., Burning of Electrical Household Appliances: An Experimental
Study, VTT Research Notes 2084, retrieved on October 1, 2001 from http://www.inf.vtt.fi/pdf/tiedotteet/
2001/T2084.pdf, Espoo, Finland: VTT Technical Research Centre of Finland, 2001.
18. International Organization for Standardization, Fire Tests—Full-Scale Room Test for Surface Products, ISO
9705:1993, Geneva, Switzerland: ISO, 1993.
19. American Society for Testing and Materials, ASTM E 1354-97: Standard Test Method for Heat and Visible
Smoke Release Rates for Materials and Products Using and Oxygen Consumption Calorimeter, West Conshohocken, PA: ASTM, 1997.
20. Babrauskas, V. and Grayson, S.J. Heat Release in Fires, 403–404. New York, NY: Elsevier Science Publishers, 1992.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 35
Part I: Electrical Power Cord Damage from Radiant Heat
and Fire Exposure—Tables and Figures
Table 1. Description of the six power cord test configurations
Test Series
Configuration
Radiant Heat (40kW/m2)
Flame Impingement
†
Horizontal exposure
(Test Series A)
Power cord suspended horizontal between two ceramic mandrels
with ½" sag in the cord midway between mandrels.†
45° Exposure
(Test Series B)
Power cord draped over ceramic mandrel with radiant heat
oriented at 45 degrees to the vertical.
Horizontal over carpet
(Test Series D)
Power cord placed on carpet with radiant heat directly above.
Horizontal over parquet floor
(Test Series E)
Power cord placed on untreated parquet wood flooring with radiant
heat source directly above.
Gas flame (Test Series C)
½" flame from gas burner impinging on the natural bend in cord
plugged into a duplex outlet.
Wood crib (Test Series F)
Power cord suspended over wood crib fire.
Radiant heat source positioned 2¼ inch above the power cord.
Table 2. Total number of power cords exhibiting electrical activity for each test configuration
Cord Type
Test Series C
Test Series E
Test Series A Test Series B
Flame
Test Series D
Radiant
Test Series F
Horizontal
45°
impingement Radiant heat
heat over
Wood
Radiant Heat Radiant Heat
on cord
over carpet wood flooring
crib fire
Total
SEL01-I
5/20
4/20
8/10
20/20
15/15
2/2
62%
SEL02-I
4/20
6/20
4/10
20/20
15/15
2/2
59%
SEL03-I*
17/20
6/10
10/10
20/20
15/15
2/2
91%
SEL04-I
10/20
4/10
8/10
20/20
15/15
2/2
76%
SEL05-I*
8/20
2/10
10/10
20/20
15/15
2/2
74%
SEL06-I
12/20
5/10
7/10
20/20
15/15
2/2
79%
SEL07-NI
4/20
0/10
10/10
20/20
20/20
2/2
68%
SEL08-NI
6/20
0/10
10/10
20/20
20/20
2/2
71%
SEL09-NI
10/20
0/10
10/10
20/20
20/20
2/2
76%
Total
42%
25%
86%
100%
100%
100%
NI indicates non-integral insulation; -I indicates integral insulation;
* indicates SPT-1 type power cord; all other power cords are SPT-2 type.
36
❖
Fire and Casualty ❖
November 2003
Table 3. Time to activity (Minutes ± Seconds)
Cord Type
Test Series A
Test Series B
Test Series C
Test Series D
Test Series E
Test Series F
SEL01-I
4:14 ± 0:27
7:01 ± 1:51
1:06 ± 0:39
3:09 ± 0:31
3:56 ± 0:42
1:51 ± 0:35
SEL02-I
5:35 ± 2:23
3:51 ± 0:48
0:59 ± 0:08
3:25 ± 0:19
4:00 ± 0:37
3:10 ± 1:13
SEL03-I*
4:45 ± 2:31
6:53 ± 2:25
0:23 ± 0:03
2:36 ± 0:18
3:18 ± 0:30
2:18 ± 1:00
SEL04-I
4:40 ± 2:16
4:13 ± 0:59
1:03 ± 0:16
3:18 ± 0:32
4:26 ± 0:49
1:25 ± 0:00
SEL05-I*
6:26 ± 3:53
3:41 ± 0:16
3:37 ± 2:33
3:22 ± 0:16
3:48 ± 0:35
2:19 ± 0:42
SEL06-I
6:29 ± 3:03
3:59 ± 0:44
2:14 ± 1:01
3:04 ± 0:36
3:29 ± 0:32
4:56 ± 0:19
SEL07-NI
4:15 ± 0:48
No Activity
1:06 ± 0:15
4:18 ± 0:24
5:21 ± 0:28
4:46 ± 0:24
SEL08-NI
5:28 ± 3:16
No Activity
0:55 ± 0:05
4:21 ± 0:32
5:04 ± 0:24
3:59 ± 2:34
SEL09-NI
7:56 ± 2:19
No Activity
0:48 ± 0:03
4:16 ± 0:20
4:45 ± 0:48
1:51 ± 0:30
NI indicates non-integral insulation; -I indicates integral insulation;
* indicates SPT-1 type power cord; all other power cords are SPT-2 type.
Table 4. Number of power cords which severed/total number of cords tested
Cord Type
Test Series A Test Series B Test Series C Test Series D Test Series E Test Series F
Total
SEL01-I
1/20
2/20
1/10
4/20
9/15
0/2
20%
SEL02-I
2/20
1/20
0/10
6/20
13/15
0/2
25%
SEL03-I*
5/20
5/10
0/10
9/20
3/15
0/2
29%
SEL04-I
4/20
2/10
2/10
8/20
8/15
0/2
31%
SEL05-I*
4/20
0/10
6/10
18/20
13/15
1/2
55%
SEL06-I
7/20
2/10
4/10
11/20
9/15
0/2
43%
SEL07-NI
1/20
0/10
3/10
18/20
18/20
2/2
51%
SEL08-NI
3/20
0/10
2/10
17/20
17/20
1/2
49%
SEL09-NI
8/20
0/10
3/10
12/20
18/20
0/2
50%
Total
19%
11%
23%
57%
72%
22%
NI indicates non-integral insulation; -I indicates integral insulation;
* indicates SPT-1 type power cord; all other power cords are SPT-2 type.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 37
Table 5. Number of power cords which severed/the number of power cords tested
which exhibited activity, severed and caused the circuit breaker to open
Cord Type
Test Series A Test Series B Test Series C Test Series D Test Series E Test Series F
Total
SEL01-I
1/1
2/0
1/1
4/0
9/8
0/0
17/10
SEL02-I
2/2
1/0
0/0
6/3
13/9
0/0
22/14
SEL03-I*
5/5
5/3
0/0
9/6
3/2
0/0
22/18
SEL04-I
4/3
2/0
2/2
8/3
8/3
0/0
24/11
SEL05-I*
4/2
0/0
6/6
18/8
13/8
1/1
42/25
SEL06-I
7/4
2/0
4/4
11/3
9/3
0/0
33/14
SEL07-NI
1/1
0/0
3/0
18/16
18/7
2/0
42/24
SEL08-NI
3/1
0/0
2/0
17/9
17/13
1/1
40/24
SEL09-NI
8/4
0/0
3/0
12/8
18/12
0/0
41/24
35/23
12/3
21/13
103/56
55/65
4/2
Total
NI indicates non-integral insulation; -I indicates integral insulation;
* indicates SPT-1 type power cord; all other power cords are SPT-2 type.
38
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Fire and Casualty ❖
November 2003
Figure 1. Test station showing (1) test lamp, (2) circuit breaker lamp, (3) circuit
breaker panel, (4) variable power supply for the radiant cone,
(5) the radiant cone positioned over line cord, and (6) the power cord
Figure 2. Damage to the conductors of a type SPT-1 power cord with integral insulation
which exhibited continuous arcing when exposed to flame (Test Series D)
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 39
Figure 3. Bead formation on the conductors of a type SPT-1 power cord with integral insulation
which severed when exposed to radiant heat (Test Series A)
Figure 4. Localized fusing / melting between conductors of a SPT-1 power cord with
integral insulation when exposed to radiant heat (Test Series A)
40
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Fire and Casualty ❖
November 2003
Figure 5. Partial severing of conductors after a type SPT-2 power cord with
integral insulation was exposed to flame (Test Series F)
Figure 6. Copper deposit and pitting on conductors of a type SPT-2 power cord
with integral insulation exposed to flame (Test Series F)
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 41
42
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Fire and Casualty ❖
November 2003
V-0
V-0
5B
V-0
4B
5A
V-0
V-0
3B
4A
HB
3A
NA = not available
5
4
3
V-0
2B
V-0
1B
V-0
V-0
1A
1
2A
V-0
Ignition 2
2
V-0
Ignition 1
Yes
1 Cordless Phone
1 Small Radio
In burn room with upholstered chair and
area rug
Yes
4 Radios
4 Telephones
1 Ans. Machine
36"
31"
27"
25"
In burn room with upholstered chair and
area rug
No
4 Radios
4 Telephones
1 Ans. Machine
TV/Radio on tables beside upholstered chair
TV/Radio on tables beside upholstered chair
Videocart under hood
Entertainment Center
Entertainment Center
36"
30"
2×27"
Yes
No
Yes
No
Yes
Entertainment Center
Entertainment Center
Entertainment Center
On videocart under hood
On videocart under hood
1 Radio
1 Radio
None
None
1 Telephone
No
No
1 Cordless Phone
1 Small Radio
1 Telephone
No
No
None
Telephone
TV & Devices
Electronic Devices Energized
Configuration
27"
27"
20"
19"
20"
20"
20"
20"
20"
20"
TV Cabinet Plastic Screen
Classification
Size
Test
Table 1. Summary of Television Full Scale Burn Tests
Newspaper and Upholstered Chair
Newspaper and Upholstered Chair
Newspaper and Upholstered Chair
Newspaper and Upholstered Chair
5 mL IPA
5 mL IPA
5 mL IPA adjacent to phone
5 mL IPA adjacent to phone
5 mL IPA
5 mL IPA
5 mL IPA adjacent to TV
5 mL IPA and telephone
External Fire Source
Part II: Full Scale Burn Tests of Television Sets and Electronic Appliances—Tables and Figures
6 min 50 sec
4 min 30 sec
3 min 17 sec
3 min 30 sec
1 min 36 sec
12 min 19 sec
16 min 5 sec
15 min 50 sec
7 min 48 sec
6 min 18 sec
5 min 34 sec
NA
Time to Ext.
Table 2. Cone calorimetry results of the entertainment center, V-0 television cabinet and common
polymeric materials [20] at an incident flux of 20 kW/m2.
Peak RHR
kW/m2
tig sec
Total RHR
MJ/m2
Average RHR
kW/m2
∆Hc
MJ/kg
Entertainment Center
197
1473
83
64
13
V-0 TV Cabinet
224
166
35
156
11
72
236
36.5
23.6
7.0
PVC WC
116
117
47.3
53.8
10.5
ABS FV
224
5198
80.7
ND
17.0
ABS FR
224
212
38.3
ND
12.5
FL PVC
233
102
116.4
111.1
19.3
DFIR
237
254
46.5
53.7
13.1
PS FR
277
244
93.0
ACET
290
259
143.9
82.2
13.0
PMMA
409
176
691.5
167.5
23.5
NYLON
517
1923
188.0
31.0
23.3
ABS
614
236
159.8
ND
56.7
PS
723
417
202.6
ND
40.7
PE
913
403
161.9
Material ID
PVC WC FR
ND
81.1
15.0
41.1
ND = not determined; PVC WC FR = Flexible wire and cable poly (vinyl chloride) compound containing fire retardants;
PVC WR = Flexible wire and cable poly (vinyl chloride) compound without fire retardants; ABS FV = Acrylonitrile butadiene styrene with poly (vinyl chloride) as an additive; ABS FR = Acrylonitrile butadiene styrene terpolymer fire retarded
with bromine compounds; FL PVC = Standard flexible poly (vinyl chloride) compound; DFIR = Douglas fir wood board;
PS FR = Fire retarded polystyrene; ACET = Polyacetal; PMMA = Poly (methyl methacrylate); NYLON = Nylon 6,6; ABS =
Acrylonitrile butadiene styrene terpolymer; PS = Polystyrene; PE = Polyethylene.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 43
Table 3. Cone calorimetry results of the entertainment center, V-0 television cabinet and common
polymeric materials [20] at an incident flux of 40kW/m2 .
Material ID
Peak RHR
kW/m2
tig sec
Total RHR
MJ/m2
Average RHR
kW/m2
∆Hc
MJ/kg
Entertainment Center
225
66
110
131
11
V-0 TV Cabinet
230
27
64
187
10
92
47
51.7
62.7
9.5
PVC WC
167
27
95.7
127.6
15.5
ABS FV
291
61
108.5
152.1
17.4
ABS FR
402
66
70.3
214.8
12.4
FL PVC
237
21
98.2
168.5
15.7
DFIR
221
34
64.1
122.7
17.6
PS FR
334
90
94.5
200.7
14.6
ACET
360
74
141.3
192.2
12.7
PMMA
665
36
827.9
486.4
23.3
NYLON
1313
65
226.3
277.9
31.0
ABS
944
69
162.5
543.9
28.8
PS
1101
97
210.1
503.7
38.0
PE
1408
159
220.9
455.9
46.6
PVC WC FR.
ND= not determined; PVC WC FR = Flexible wire and cable poly (vinyl chloride) compound containing fire retardants;
PVC WR = Flexible wire and cable poly (vinyl chloride) compound without fire retardants; ABS FV = Acrylonitrile butadiene styrene with poly (vinyl chloride) as an additive; ABS FR = Acrylonitrile butadiene styrene terpolymer fire retarded
with bromine compounds; FL PVC = Standard flexible poly (vinyl chloride) compound; DFIR = Douglas fir wood board;
PS FR = Fire retarded polystyrene; ACET = Polyacetal; PMMA = Poly (methyl methacrylate); NYLON = Nylon 6,6; ABS =
Acrylonitrile butadiene styrene terpolymer; PS = Polystyrene; PE = Polyethylene.
44
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Fire and Casualty ❖
November 2003
Figure 1. Residential fires involving televisions, radios, VCRs, and phonographs between 1980 and
1997 (Data from NFPA U.S. Home Product Report (ref. 8)).
Figure 2. Rate of heat release data calculated by oxygen consumption calorimetry during the full
scale burn tests of televisions and electronic appliances.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 45
Figure 3. “V” pattern on the wall of the burn room after Test 5B.
The “V” pattern is not indicative of the fire origin.
Figure 4. Post flashover fire photograph of the burn room which contained an upholstered
chair, area rug and multiple televisions and electronic appliances. The differential burn
patterns on the walls are not indicative of the fire origin. The first material ignited was the
upholstered chair located in the center at the rear wall shown in the photograph.
Figure 5. Electrical activity on the conductors inside the V-0 television cabinet from Test 2B.
The television was energized but the origin of the fire was outside the television cabinet.
46
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Fire and Casualty ❖
November 2003
Figure 6. Electrical activity on the conductors of the transformer from a HB radio used
in Test 5B. The radio was energized but the origin of the fire was outside the radio.
Figure 7. Damage to the conductors of a V-0 television line cord resulting from
an exposure fire (Test 1B). The television was energized but the origin of the fire
was outside and to the left of the television cabinet.
Figure 8. Severed electrical blades from the line cord of a HB answering machine in Test 5B.
Electrical Power Cord Damage and Full Scale Burn Tests
❖ Hoffmann
❖ 47
Figure 9. The circuit board of this V-0 television was exposed to post flashover conditions but was
protected by other components of the television including the picture tube glass and shadow mask.
Figure 10. Example of localized damage to the circuit board components
inside the V-0 television used in Test 1B.
Figure 11. Uniform fire damage to the circuit board inside a V-0 television from
Test 5B. The television was energized and exposed to flashover conditions.
Return to Course Book Table of Contents
48
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Fire and Casualty ❖
November 2003