2020 NEC AFCI

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kwired said:
Problem with AFCI is it mostly focuses on examining characteristics of the current wave form (I think, they kind of keep the details more top secret then national security issues:blink:) There are way too many possible patterns to recognize and there is potentially some that are acceptable that get rejected anyway because they are not acceptable in other situations. And anything unknown but questionable probably is rejected.
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Analyzing the current waveform was a flawed theory from day one better than 15 years ago. It hasn't become possible with any more reliability today. There is no way to discern normal electrical disturbances from abnormal ones with any certainty.

-Hal
 
hbiss said:
Analyzing the current waveform was a flawed theory from day one better than 15 years ago. It hasn't become possible with any more reliability today. There is no way to discern normal electrical disturbances from abnormal ones with any certainty.

-Hal
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I agree and did from the beginning. They can try all they want to develop something that does work reliably, but what they did wrong (for the industry) was sell the concept to code making panels and say it is all in the name of safety - so they can profit while attempting to further perfect the product, which may or may never happen, improvements were made but will likely never be close to perfected.

Then there is the "glowing connection" issue that IMO is a cause of many electrical fires that doesn't get detected - or if it does is already too late in the game.
 
romex jockey said:
So why can't we have afci mains?

~S~
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I know Peter D brought up the main AFCI as a bad idea, but to elaborate it would result in clearing the whole home for a nuisance trip which AFCI are very good at. Even in Europe where main RCDs were/are common the trend is to have several submain RCDs or individual RCBOs in new installations.
 
peter d said:
That sums up my belief and likely many others as well. Whole house GFCI protection makes perfect sense to me if a whole house solution is desired, although I don't think it's necessary. Given the choice between AFCI and GFCI, GFCI wins hands down. I really have no idea why the industry pursued AFCI when a proven technology was already available.
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I think- bare with this theory for a moment: Marketing. A GFCI is a GFCI. An AFCI is a whole new price point. As such you can require both and secure the sale of two "different" technologies or devices where only one price point would have been present in a fair, honest world.
 
romex jockey said:
Few ask why, if afci technology is so great, it's not a worldwide phenomenon


the quick answer is, because it's existed outside the US for generations , under terms like RCD, differential and toroidal.



The reality being we're not 'leading edge' , we are mimicking the tried/true cloaked in the guise of marketing and packaging.



Right now NEMA has a 'road show' of numerous sparks that are proliferating IAEI and other trade org meetings, Manufacturers continue to write articles stating nefarious stats, have 'afci' websites ,and have essentially banded together creating a national narrative.


They've also taken great pains to silence the nay sayers ,and either buy or wait out any competition via a string of patent wars.


Only one voice exists, Joe Engel , whom was their leading R&D man

No trade rag will touch it (we've tried) , anyone connected with the NFPA will discredit and/or denounce it (as we've seen in this forum) , and CMP-2 refuses to opine on it


there's a reason for that, which is why it needs to be spread around more

thx

~RJ~
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This sadly, I have to agree with. See reply below :)


kwired said:
Those aren't the same thing. AFCI's may utilize some of the same features though.

Problem with AFCI is it mostly focuses on examining characteristics of the current wave form (I think, they kind of keep the details more top secret then national security issues:blink:) There are way too many possible patterns to recognize and there is potentially some that are acceptable that get rejected anyway because they are not acceptable in other situations. And anything unknown but questionable probably is rejected.
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In terms of what they are trying to accomplish, they are one in the same.


What UL and other AFCIs players will not tell you as that AFCIs were originally created with the wholehearted intent to mimic European technology. The theory started when someone pitched the idea that European circuit breakers were more likely to trip faster on shorted lamp cords and shorted NM. It was then postulated that faster tripping in Euro breaker prevented fires and the slower tripping on US breaker resulted in fires. This evolved into UL creating hundreds of test "scenarios" demonstrating how European breakers and RCDs tripped faster than US breakers- which was easy to do with a short circuit deprived source and a dull guillotine slowly trying to sever a zip cord. Of course the European breaker with the lower magnetic pickup tripped first in such a rig. And it does look convincing on the surface- Square D used a similar concept to market their QO breaker which had a lower magnetic pickup and would trip out first when placed in series with a competitor's breaker.


As such it was proposed (and it actually happened) to lower the the trip thresholds on US residential breaker. Then comes along a theory that some homes might have POCO short circuit levels very well below below 500amps- say 150amps. This low level plus the impedance of the branch circuit might not trip the breaker magnetically (fast enough). Trip more than a few cycles= fire :roll: Is was then theorized the lowest short circuit current that anyone could ever find in a home under all and worst case conditions would be at 75amps. Again- only a theory and pretty much assumption.

So the orginal proposed solution to this problem was a 75amp solenoid coil in every 15 and 20amp breaker. However, 75amps is below the inrush of most appalinces like Vaccum cleaners. So then the idea was that instead of useing a coil looking for a magnitude of 75amps, a circuit board looking for the sputtering waveform of a short circuit beggning at 75amps would be used instead. So a vaccum of cleaner with an inrush of 120amps would not trip, but if sputtering was deteceted at 120amps, the circuit board would trip the breaker in a few cycles. The modern AFCI breaker was born.


As for the term arcing, its just marketing babble. Very earlly on the sputtering from severed cords was renamed as "arcing". However, arcing and sputtering are to very different thinks. Even by UL's own indirect citing of Paschens theory, arcing is not possible at 120 volts. So the theory of carbonization comes along to patch that hole... supposed lightning strikes glaze the over driven staple- that would kill the AFCI electronics in the first place. I guess thats where self testing will come in...



And the biggest irony of all... AFCIs are now being pitched to the European IEC world as something new and orginal. Truth is its not- for 25 years UL and others were ARGESIVELLY trying to mimick European technolochy while trying to twist reality that 120 volts could sustain an arc the same way 230 volts can.
 
mbrooke: Sorry, that 120V does not sustain an arc is not correct: 120V carbon electrode arc lamps were used in projectors of movie theatres in the past!
 
Sahib said:
mbrooke: Sorry, that 120V does not sustain an arc is not correct: 120V carbon electrode arc lamps were used in projectors of movie theatres in the past!
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Yup- and thats why UL had to create the carbonization theory. Lightning and high voltage surges in the order of thousands of volts carbonize the damaged cable insulation which creates a sustained current flow across the carbon path. Only problem being that these high voltage spikes will damage the electronics within AFCIs.
 
Sahib said:
mbrooke: Sorry, that 120V does not sustain an arc is not correct: 120V carbon electrode arc lamps were used in projectors of movie theatres in the past!
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120V cannot sustain metal-to-metal arcing. It can sustain arcing when a carbon electrode is consumed during the maintenance of the arc.
 
ramsy said:
Can 240v arcs be sustained between any 2 legs with 240v potential, or any similarly damage cables?
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Yes- at approximately 234 volts you gain the ability for an an arc to sustain itself in regular air. This is assuming several conditions are met and the conductors are in very close proximity (practically touching) to one another. Often the breaker or fuse needs to be oversized to hold on the arcing current.


Here is a real world example of a sustained arc fault on a 230 volt (nominal) supply:



https://www.youtube.com/watch?v=-qCuXF9eDBM
 
ramsy said:
Is there any evidence or demonstration of AFCI devices interrupting these arcs?
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Well, that depends on how you put it- or view it. AFCIs have detected such arcs in simulated lab testing as have GFCIs, GFP, fuses and circuit breakers. Now if the arc signature component will catch such an arc in the real world is not known.
 
romex jockey said:
I'd simply encourage any interested party to 'field test' them, like>>>

https://youtu.be/iLmC5quELrE

~RJ~
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Or this :lol:


https://www.youtube.com/watch?v=-rfqqNg-uVE


Honestly, every lab video I question in that you have no idea what parameters are present. Also notice in the first video how the white sleeve fell and the arcing continued. Not saying AFCI don't trip on simulated/stimulated arcing, but I often wonder how that reflects the real world. Hollywood can make a fuel tank explode with a bullet, in the real world folks often can't. Sorry, bank robbers.
 
mbrooke said:
I think- bare with this theory for a moment: Marketing. A GFCI is a GFCI. An AFCI is a whole new price point. As such you can require both and secure the sale of two "different" technologies or devices where only one price point would have been present in a fair, honest world.
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Supply and demand factors into it as well. By putting emphasis on getting AFCI's to be required by code you somewhat secure the demand part. (whether they do what you say they are suppose to do or not)

GoldDigger said:
120V cannot sustain metal-to-metal arcing. It can sustain arcing when a carbon electrode is consumed during the maintenance of the arc.
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and if you don't replace the consumed carbon it will not be sustained. Just like when welding with a stick or wire feed welder - if you don't continue to feed material into the arc - it eventually will go out.
 
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