An analysis of heat flux induced arc formation in a residential electrical cable

Novak, Cameron J.; Stoliarov, Stanislav I.; Keller, Michael R.; Quintiere, James G.

doi:10.1016/j.firesaf.2012.10.007

Cited by 26 publications

(14 citation statements)

References 6 publications

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“…5 shows a typical near-failure current history observed in these experiments. Even at a high temporal resolution, the transition between no current and high current appears to be instantaneous, which is consistent with our previous observations [13].…”

Section: Cable Testssupporting

confidence: 93%

“…The failure was observed in every test. The time to failure was significantly more reproducible than that measured in the previous experiments where the same cable was exposed to a constant radiant heat flux [13]. The temperature of the cable was found to follow the temperature of the oven (shown in Fig.…”

Section: Cable Testssupporting

confidence: 55%

“…This observation supports the failure mechanism that is similar in nature to a dielectric failure. This mechanism is discussed in detail in our previous publication [13]. A hypothesis that it is a chemical interaction between the products of decomposition of PVC and paper that initiates this failure will require additional research.…”

Section: Discussionmentioning

confidence: 95%

“…In particular, determining whether an electrical cable failure is the source of ignition or simply a result of an already existent fire has been a problem for many in the fire investigation community [3]. A failure of energized cable frequently causes an arc, which is defined as an electric discharge across a gap or through a semi-conductive medium [4,5]. For residential purposes, arcing events (or faults) can be divided into two main categories: series and parallel.…”

Section: Introductionmentioning

confidence: 99%

“…These models describe transient heat transfer inside the cable and rely on the notion of a critical insulation temperature at which an arc fault takes place. The results of a study conducted recently by our group [13] performed on a 14 American Wire Gauge (AWG) nonmetallicsheathed cable suggest that the timing of an arc fault is defined by a critical degree of the thermal decomposition of the electrical insulation, which is a function of both local temperature and time.…”

Section: Introductionmentioning

confidence: 99%

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A criterion for thermally-induced failure of electrical cable

Fisher

Stoliarov

Keller³

2015

Fire Safety Journal

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Section: Cable Testssupporting

confidence: 93%

Section: Cable Testssupporting

confidence: 55%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A criterion for thermally-induced failure of electrical cable

Fisher

Stoliarov

Keller³

2015

Fire Safety Journal

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Leakage currents precede short circuits in PVC‐insulated cable when exposed to external radiant heat

Iwashita

Keller²,

Hagimoto³

et al. 2016

Fire and Materials

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Summary The mechanism of how and when an arcing short or a physical short occurs on a polyvinyl chloride (PVC)‐insulated cable when exposed to radiant heat flux has been found experimentally. How this mechanism acts on the size of the resulting arc beads is also considered. As a physical short usually changes into an arcing short in an instant, it is difficult to determine which type of short circuit occurs as the first phenomenon. To solve this difficulty, a short circuit current was limited to the order of an ampere, which is large enough to trigger an arcing short, and short circuit tests were conducted with a PVC‐insulated cable. Before an arcing short, a small amount of leakage current in the order of milliamperes was observed flowing through PVC insulation, which gradually increased and finally turned into an arc. On the other hand, no leakage current was observed before a physical short. These results indicate the following mechanism: When PVC insulation between conductors in a cable melts when a heat flux is applied, conductors often come close to and into contact with each other. In this case, the leakage current is unrecognizably small because the PVC insulation is not yet carbonized and still has a high resistivity. Meanwhile, when conductors do not come into contact with each other, PVC insulation is gradually carbonized and the leakage current increases until an arcing‐through‐char occurs. Copyright © 2016 John Wiley & Sons, Ltd.

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Characterization of arc beads on energized conductors exposed to radiant heat

Iwashita

Hagimoto²,

Sugawa

2017

Fire and Materials

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Summary It has been discovered through experimentation the mechanism of how and when an arcing short or a physical short occurs on a cable when exposed to a radiant heat flux. It is then considered how this mechanism acts on the size of the resulting arc beads. Another discovery was that a leakage current precedes a short circuit. Subsequently, it was found that arcing shorts and physical shorts can be distinguished based on the amount of leakage current that precedes the short circuit. In the case of an arcing short, the leakage current is large and the arc bead is small. The opposite is true for a physical short. In the case of a physical short, the leakage current is small and the arc beads are large. Tests were conducted with a Japanese polyvinyl chloride (PVC)–insulated sheathed cable, an American PVC–sheathed non‐metallic (NM) cable, and an American cloth–sheathed NM cable. The following were found: A Japanese PVC–insulated sheathed cable tends to cause a physical short and to form larger arc beads than other cables. American NM cables tend to cause an arcing short. Especially, an American cloth–insulated cable tends to be preceded by a larger leakage current and to form smaller arc beads than other cables. This result corresponds to the experimental description in NFPA 921 concerning arc beads on a cloth‐sheathed NM cable.

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An analysis of heat flux induced arc formation in a residential electrical cable

Cited by 26 publications

References 6 publications

A criterion for thermally-induced failure of electrical cable

A criterion for thermally-induced failure of electrical cable

Leakage currents precede short circuits in PVC‐insulated cable when exposed to external radiant heat

Characterization of arc beads on energized conductors exposed to radiant heat

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