Burning Wirenut

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Sierrasparky said:
could one of the cables wicked water into the box.
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No, there is no drains, no roof drains, no pipes or signs of leaks, if you look the cables loop over the I beam and stay under the slab. The beams are covered with a fiberglass fire proof material and always dry,I hope the picture is clear by the beam.
I really can not tell how the the box is rusted. Maybe one of the other members can tell if the heat and fire could cause it????
 
mike7330 said:
No, there is no drains, no roof drains, no pipes or signs of leaks, if you look the cables loop over the I beam and stay under the slab. The beams are covered with a fiberglass fire proof material and always dry,I hope the picture is clear by the beam.
I really can not tell how the the box is rusted. Maybe one of the other members can tell if the heat and fire could cause it????
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Hi Mike, what I know after having spent 10 years studying these phenomenons, is that heat generates always oxidation. I'm not surprised. There are often problems with the connections of heating element ( hot water tanks, etc.) because of this. Probably elements favorable to the ignition of fire were present in this box...Perhaps not much was missing before a fire would have started. And if this box was in a house built of wood, with Romex stapled to wood studs?

Regards,
 
AFCIs vs heat detection devices

AFCIs vs heat detection devices

AFCIs, whether branch circuit type or combination type, DO NOT protect against series arc faults. I know - I've tested them, and they do not ever de-energize the circuit when the arcing is in a series circuit. No matter how careful the electrician who does the installation is, or how good the quality of the equipment and tools used for the installation, or how good the actual splicing devices are - failures still occur. AFCIs will not protect residences from arc faults - they have differential protection similar to GFCIs, so they will trip in a parallel arc fault (phase to ground). Devices that can detect a hot spot, or loose connection, in an electrical installation are needed to prevent fires. I am encouraged to see this technology being developed. Stay tuned, folks. It's coming, and it's a good thing.
 
edward said:
I need to disagree with you. Once the connections are done correct using the correct material and are in the correct environment then they shouldn't come apart.
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I should be rich and good looking too .... instead of just good looking.:)
 
mike7330 said:
No, there is no drains, no roof drains, no pipes or signs of leaks, if you look the cables loop over the I beam and stay under the slab. The beams are covered with a fiberglass fire proof material and always dry,I hope the picture is clear by the beam.
I really can not tell how the the box is rusted. Maybe one of the other members can tell if the heat and fire could cause it????
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Mike some explanations:

http://c-joule-effect-inc.com/cjouleeffectincglowing_connections-electrical_-1.html

Regards,

ICC
 
I would like to observe that burning plastic -and I have participated in burning up rooms packed with tons of wires and cables- produces an extremely corrosive smoke and corrosive ash.

Indeed, the plating on our tools was eaten up in no time at all- nevermind the much thinner plating on the strut and such. It was as if the ash was pure hydrochloric acid.

Plus, burning anything creates a significant amount of moisture. Anyone who has used a catalytic heater in a tent can attest to this.

Finally, corrosion radically increases with an increase in temperature.

Add it all up, and that rust and crud just might be the result of that connection 'cooking' for awhile.

Or, perhaps, it was installed already rusted.
 
So how far are they from implementing the GCI technology? Are the connectors reusable? Will they work on different configurations than just straight through splices? Can it be built into devices?

It seems like a reasonable and useful technology, although it would only protect those connections being made by a professional which would still not eliminate the dangers associated with bad cord ends, damaged cords, loose receptacle prongs, bad device connections etc.
 
George Stolz said:
I have a technology that already prevents the fires this device protects against:

00973710000


;)
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Try an experiment. Twist you wires together cut them off as you normally would then put your foot on one and pull the other, comes apart? Now pair up with no twists, put a wire connector on. Pull again. Come apart? Your a pretty tough guy if it did. I know, just think how tough it would be it they were twisted too. I've seen twists so screwed up it might have been better to just tape them and go home.
 
don_resqcapt19 said:
I have not seen anything that would lead me to believe that an AFCI, even of the combination type, will detect and clear a high resistance connection. There are two issues. First is it an arcing connection. A high resistance connection can produce enough heat to cause a lot of damage without being an arcing connection. Second you can produce a lot of heat in a small area with currents less than 5 amps. Even if it is a series arc, the AFCI does not look at the arc signature unless the current exceeds 5 amps.

It is my opinion that this type of problem is the main reason why most brands of AFCIs have GFP protection. At some point, hopefully before the building is on fire, this type of fault will become a ground fault and the GFP part of the AFCI will clear the circuit. It seems to me that the newer GE AFCIs, without ground fault protection lose a lot of their ability to protect in cases like this.
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This bears repeating, as well as adding that UL has recently recognized the glowing contact as a chief player in electrical fires

A Mr Joe Engle mentions this i his latest IEEE papaer, as well as expands on what is basically historic commentary of the evolution leading up to this point

http://www.combinationafci.com/resources/doc_ieee_combination_afci.pdf

~rj~
 
edward said:
I need to disagree with you. Once the connections are done correct using the correct material and are in the correct environment then they shouldn't come apart.
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So mechanical things never fail?:happysad: How come there are so many places that offer repair services?

romex jockey said:
Folks

please note this series event was not mitigated by either gfci or afci

~RJ~
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I did not expect GFCI to trip unless you are lucky for a conductive path to ground to develop. Then the AFCI would trip also but because of the GFCI component built into it.

This is a common occurance yet the industries millions of dollars of reasearch did not find a reliable way to detect it, and forced us to use a product that maybe does very little for us.
 
I see no reason to provide another type of protector for this issue when requiring GFP protection on the already required AFCIs will provide protection from this issue in most cases. As the glowing connection melts the insulation, it is very likely that a ground fault will occur within the box and the circuit would trip prior to having enough heat to ignite something inside or outside the box.
 
don_resqcapt19 said:
I see no reason to provide another type of protector for this issue when requiring GFP protection on the already required AFCIs will provide protection from this issue in most cases. As the glowing connection melts the insulation, it is very likely that a ground fault will occur within the box and the circuit would trip prior to having enough heat to ignite something inside or outside the box.
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What happens if a ground fault does not occur? I have uncovered many connections - not so many wire nuts but mostly switches or receptacles where this happened and no ground fault - just eventually burned itself until the circuit was open. If it happens with 277/480 it is usually even worse looking and often you don't even have to remove any cover to tell there is a problem in the box.
 
don_resqcapt19 said:
I see no reason to provide another type of protector for this issue when requiring GFP protection on the already required AFCIs will provide protection from this issue in most cases.
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Don, according to Joe Engel in the paper previously linked to, the manufacturers have pulled the GFP from the combination AFCIs.

Being circuit breakers, both types provide both overcurrent
and overload protection. All Branch/feeder AFCIs provide
ground fault (30mA) protection, while manufacturers are
removing this feature from their Combination AFCIs. Both
AFCIs provide protection against parallel arcing, while neither
provides protection against series arcing. The UL 1699 AFCI
standard only tests for parallel arcing; it doesn?t test for ground
fault or series arcing.
The importance of ground fault goes beyond shock
protection; it in combination with arc fault protection has been
shown by UL to mitigate the effects of a ?glowing contact?.
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Leaves me to wonder, what exactly is left in the little black box? :slaphead:
 
What is the most likely cause of all the splices burning that you guys have posted? It looks like a lot of the glow arcs are starting beyond the wirenut, back where the insulation is. Is that the case or are even well twisted splices at risk for burning up?
 
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