Pyrophoric carbonization

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GoldDigger said:
Mr. Kirchoff's rules apply even to a one load series circuit, you just don't need to use them for analysis.
But, yes, the service neutral can be elevated from ground enough to cause carbonization even though the service line wires are open.
Simplest example is a duplex with one drop and two meters and an open POCO neutral upstream.. Opening one main leaves both neutrals hot.
(I think I saw the same video you did.). :)
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Yes , and i'd dearly like to find said video GoldOne.....

~RJ~
 
Curious nerd said:
Can anyone think of a safe way to do a test applying 120V through either old or new construction-grade softwood?
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Use a current limited AC supply with an inverse time characteristic, not a direct line supply. A resistive or inductive current limiter might inhibit the pulse of current associated with a micro arc. A series capacitor might work.
Enclose the wood in a fireproof enclosure and use high temperature wire.
 
junkhound said:
400 or 500 uA (yes MICRO, e-6 amps) is sufficient to cause tracking to start and tree on any surface, even Teflon, glass, and glazed ceramic. Have run tests on everything from Torlon and Teflon to glass and bakelite and even wood.

Basic process is that the conductive moisture film (even condensed fog) on something like TFE or polyimide conducts a few hundred uA when there are any contaminates. When the film breaks on something hydrophobic like TFE, or a section dries out like on wood, the first point of the high resistance current break arcs and carbonizes a tiny spot. This spreads on repeated wet dry cycles. Can take months or years for 120V in a seldom wet environment, at 480V where there is fog it can happen in weeks. Testing where a continuous spray and dry cycle is applied, the time to track between cm separations at 500 Vdc is only minutes. Faster above paschen minimum voltages.

On materials like glass and Teflon, the surface is just etched and no carbon path is created, just craters for more contaminates to collect over time, which may have organic materials that can create a conductive path (typically years). Any organic insulator will track. An IEC test for this is comparative tracking index, CTI.
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Obviously you're up on this Junk

So please educate us , the IEC has some test? Paschen's laws? ....?

~RJ~
 
Curious nerd said:
Can anyone think of a safe way to do a test applying 120V through either old or new construction-grade softwood?
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Golddigger already gave you one answer, I'll just add in some historical notes for the 'young squirts' here who do not know the origin of the term 'breadboard' for electronic circuit prototyping.

Even 40 years before us old (nearer 4 score than 3 score) farts were born, guys would appropriate the distaff lady's board she used to knead bread on, and pound it full of small nails.
Then you would solder the components to these 'terminals', add nails as you expanded the circuits.

Now of course, back in those high temp high voltage tube days, if the lady demanded her 'bread board' back or 'no supper', the electrician in the house would have to pull the nails if he wanted any homemade bread. So, every time the 'breadboard' got switched back and forth from making bread to prototyping circuits, , there would be lots of moisture in the holes, so carbonization was quite common given that most plate voltages to cathode or filament was 650 or so volts and often only 1/4" apart.

Note for the really old guys over about 80:
I never met anyone who did circuit design and who built cat whisker radios as a kid before 1947 who did not bang their head and say " I could have been the inventor of the transistor if I'da just thought about it some more"
 
romex jockey said:
afci's are completely irrelevant to the topic

~RJ~
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Listen here. I am probably the best on my block when it comes to electrical stuff. Maybe even my entire neighborhood.

AFCI's are today's seatbelt. There were passive restraint system haters back then just like there are AFCI haters today.
 
DeltaFarce said:
Listen here. I am probably the best on my block when it comes to electrical stuff. Maybe even my entire neighborhood.

AFCI's are today's seatbelt. There were passive restraint system haters back then just like there are AFCI haters today.
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There is one very big difference to your analogy.
Like them or not, seat belts work. And they work better than previous alternatives.

With AFCIs, there is not a lot of evidence that they detect anything harmful in a residential situation that an "old fashioned" GFCI breaker would not have detected just as well.
And the newer AFCIs that do not have GFCI functionality are, IMHO, a lot less safe than a GFCI.
Now the dual function AFCI/GFCI breakers may really do a good job, but probably not much better than the GFCI alone.

JMO
 
GoldDigger said:
There is one very big difference to your analogy.
Like them or not, seat belts work. And they work better than previous alternatives.
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The people who put AFCI's in code are infallible. They wouldn't have made AFCI's a code requirement unless they were absolutely, positively, 100% perfect and ready to save lives.
 
DeltaFarce said:
The people who put AFCI's in code are infallible. They wouldn't have made AFCI's a code requirement unless they were absolutely, positively, 100% perfect and ready to save lives.
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In a perfect world where benevolent souls are the norm, and who knows maybe the NFPA is.

But, explain to us who are not as smart, how do AFCIs save lives? What are the mechanisms of action behind that?
 
DeltaFarce said:
Listen here. I am probably the best on my block when it comes to electrical stuff. Maybe even my entire neighborhood.

AFCI's are today's seatbelt. There were passive restraint system haters back then just like there are AFCI haters today.
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Grand

I want your autograph

Now that we've established that, can we please discuss the topic at hand, which has nothing to do with your forte'?

~RJ~
 
DeltaFarce said:
The people who put AFCI's in code are infallible. They wouldn't have made AFCI's a code requirement unless they were absolutely, positively, 100% perfect and ready to save lives.
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Well, it took me reading a few replies and this one finally opened my eyes about the 'farce' part of screen name :lol::angel::slaphead:
I think you have found that most folks AGREE with you on AFCI , heh, heh.


farce: noun nonsense, satire


 
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