210.12- Arc Resistance Found to be only 0.03 ohms

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mbrooke

mbrooke

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According to this ROP citing UL's study, a parellel arc fault has an impedance of only 30 milliohms or 0.03 ohms.

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This again would support what I've been saying all along: An arc fault is NOTHING more than a typical short circuit. This would further indicate that there is no arcing whatsoever as defined by paschen's law- we never even go past townsend discharge.

And of course 500 amps at the panelboard- the key (hypothetical) number holding back NFPA 70 from declaring that ordinary circuit breakers are capable of providing complete arc fault coverage for most typical run lengths.
 
So...
Your saying an arc fault and a short circuit are the same thing?

poppycock and balderdash...
 
How about 240? Where is the Paaschen's law threshold for metallic surfaces in air?

FWIW the test used for AFCI parallel fault at 120V uses a pyrolized surface path, so Paschen's law does not apply. On the other hand, I would not necessarily call it an ARC fault at that point.
 
GoldDigger said:
How about 240? Where is the Paaschen's law threshold for metallic surfaces in air?

FWIW the test used for AFCI parallel fault at 120V uses a pyrolized surface path, so Paschen's law does not apply. On the other hand, I would not necessarily call it an ARC fault at that point.
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At the higher end of 240 volts to ground arcing is possible in theory.

https://www.researchgate.net/public...reakdown_in_Air_over_Very_Small_Gap_Distances

However, over driven staple testing at UL found several kv necessary to break down the gap.

Testing done by Legrand now says surge protection devices are very likely to prevent break down and subsequent carbonization.
 
GoldDigger said:
How about 240? Where is the Paaschen's law threshold for metallic surfaces in air?

FWIW the test used for AFCI parallel fault at 120V uses a pyrolized surface path, so Paschen's law does not apply. On the other hand, I would not necessarily call it an ARC fault at that point.
Click to expand...

330 volts peak:


1617995834996.png
 
There is an electrician on YouTube that just loves AFCI.... maybe I’ll invite him, in the comment section, to this forum. He loves grounding electrodes too.
 
gar said:
210410-1734 EDT

An arc is not a constant resistance device, but rather an approximately constant volt
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Perhaps, but UL has it down at 0.03%. At 125% over a breaker's mag trip its said the circuit is protected from arc faults.
 
210410-2010 EDT

Most of my last post was lost.

An arc is a constant voltage type of load over a wide current range. The arc voltage drop is a function of length, gas, and pressure.

.
 
gar said:
210410-2010 EDT

Most of my last post was lost.

An arc is a constant voltage type of load over a wide current range. The arc voltage drop is a function of length, gas, and pressure.

.
Click to expand...


Right, if you have an actual arc.

At 120 volts your dealing with sputtering, a short circuit which in its simplest terms is merely a rapidly intermittent short circuit.
 
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