Glowing connections

Ettling, Bruce V.

doi:10.1007/bf02473119

Cited by 8 publications

(5 citation statements)

References 3 publications

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“…Aronstein, Beland, Ettling, Speltzer, and Horine [2][3][4][5][6] began more closely investigating glowing connections in the early 1980's. Interest in faulty connections and electrical failures developed when many jurisdictions banned the use of aluminum branch circuits after it was discovered that the fault rate of these circuits was much higher than their copper counterparts.…”

Section: Fire Technology 2006mentioning

confidence: 99%

“…Ettling [5] developed glowing connections using a steel nail in contact with a copper or aluminum wire. He varied the load by using one or two resistance heating elements.…”

Section: Fire Technology 2006mentioning

confidence: 99%

“…The required volume of contact for a wire screw connection, assuming v = 0, ρ = 1.8 * 10 −8 m, I = 15 A, and ϑ = 60 (based on the rating of a 14-gauge copper conductor) [12], would be V c = 4.82 * 10 −9 m 3 (5) where V c = π r 2 L. A solid 14-gauge wire has a diameter of approximately 1.63 × 10 −3 m; therefore, the length of the wire contacting the screw terminal for 14-gauge wire should be no less than 2.31 × 10 −3 m (0.0909 inch).…”

Section: Contact Sizingmentioning

confidence: 99%

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Heating at Electrical Contacts: Characterizing the Effects of Torque, Contact Area, and Movement on the Temperature of Residential Receptacles

2005

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Testing was performed using 120 volt, 15-amp receptacles and copper wire to determine the effect of torque and wire contact area on temperature elevation at receptacle screw terminals. Torque was varied on both the hot and neutral terminals from 0 to 12 inlbs, and the apparent wire contact at the screw terminal was varied by 1/8 and 5/8 . There was no significant difference in temperature when changing apparent wire contact. Increased temperatures were observed with reduced torque, however, they were not significant enough to initiate a glowing connection, nor high enough to cause rapid oxidation. Further testing showed that movement of a loose connection was necessary to cause significantly high temperature changes, arcing and sparking, rapid oxidation, and in some cases, glowing connections.

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Section: Fire Technology 2006mentioning

confidence: 99%

“…Ettling [5] developed glowing connections using a steel nail in contact with a copper or aluminum wire. He varied the load by using one or two resistance heating elements.…”

Section: Fire Technology 2006mentioning

confidence: 99%

Section: Contact Sizingmentioning

confidence: 99%

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Heating at Electrical Contacts: Characterizing the Effects of Torque, Contact Area, and Movement on the Temperature of Residential Receptacles

2005

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“…Eventually, high-resistance connections can heat to the point of glowing, which can persist for minutes, hours, or days [3]. Overheating and glowing connections have been studied in copper wiring by a number of authors [3][4][5][6][7][8][9]. These studies used different methods to initiate a glowing connection and examined a wide range of currents (0.5-20 amps) and voltages (120-220 volts AC).…”

Section: Introductionmentioning

confidence: 99%

Electrical Receptacles - Overheating, Arcing, and Melting

Benfer¹,

Gottuk²

2014

Fire Saf. Sci.

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This study was designed to experimentally characterize factors that can cause electrical failures (i.e., overheating connections), to assess the damage and potential forensic signatures of these failures, and to characterize the similarities and differences between arcing and melting in receptacle components and wiring. Laboratory testing evaluated the impact of a wide range of variables on the formation of overheating connections in residential duplex receptacles including screw terminal torque, wiring method (back-wired, or side-wired), and primary receptacle materials. A total of 408 trials of receptacles with various terminal connections were tested in the laboratory setting; receptacles were powered for up to 16 months. A small portion of receptacles with loose connections overheated to the point of failure of the receptacle; some including flaming events. Failure events occurred between 5 and 365 days after tests were started. Four hundred and sixty eight (468) receptacles were placed in compartment fire tests and furnace fire tests. These tests were designed to evaluate the persistence after fire exposure of overheating/arcing evidence from failure events (i.e., from potential fire cause events). The fire exposure tests also served to analyze the characteristic traits of arcing and melting damage. The results indicated that only very loose connections (less than 0.339 N-m [3 in-lb]) at moderately high currents (9A or higher) tend to form significant overheating connections and receptacle failures, irrespective of other variables such as receptacle materials and installation. Characteristic indicators of overheating and glowing terminal connections were identified and were found to persist after fire exposure.

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“…Newbury, et. al, described a glowing process in loose aluminum wire/brass and iron connections that formed high temperatures [6]. Ettling identified the oxidation process of the interface as the initial start of the glow formation [7]. Sletbak, et. al, showed current and voltage waveforms that corresponded to a glowing connection on copper and identified the oxide as Cu2O [4].…”

Section: Introductionmentioning

confidence: 99%

Glowing Contact Physics

Shea

2006

Electrical Contacts - 2006. Proceedings of the 52nd IEEE Holm Conference on Electrical Contacts

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There has been very little published research on glowing connections, especially their mechanisms and properties. In this study, oxide conductivity, surface x-ray maps, temperature measurements, and electrical waveforms were used to identify the structure and composition of glowing connections. It is shown that a glowing connection consists of a glowing molten liquid filament, which produced the orange glow that meanders on the surface of a solid copper oxide bridge that forms between two wires.Temperature and video measurements indicate that the glowing filament is in a liquid state.With the addition of oxide bridge resistivity measurements, the saw-tooth voltage pattern, typically seen in currents below 5Arms, has been explained. Also, when the glowing connection was slowly cooled, an impression of the glowing filament remained on the solid oxide. Subsequent SEM and x-ray mappings of this glow track revealed a track rich in copper, oxygen, and sulfur. This glow track explains the occasional low resistance path across the wires that can occur when the solid oxide bridge remains intact after cooling. Measurements in vacuum showed that oxygen was necessary to sustain the glowing filament even if there was a preexisting CuO oxide bridge present. Physical parameters affecting glow characteristics will be discussed; especially the semi-conducting nature of the copper oxide, and a model of the glowing contact, based on this data, that show some of the significant factors controlling the glow.

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Glowing connections

Abstract: This paper gives the results of a series of experiments and how they shed light on problems of electrical fires. Experimental glowing connections were made by allowing wires to make poor contact with another object in series in a circuit.

Cited by 8 publications

References 3 publications

Heating at Electrical Contacts: Characterizing the Effects of Torque, Contact Area, and Movement on the Temperature of Residential Receptacles

Heating at Electrical Contacts: Characterizing the Effects of Torque, Contact Area, and Movement on the Temperature of Residential Receptacles

Electrical Receptacles - Overheating, Arcing, and Melting

Glowing Contact Physics

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