2017 NEC AFCI

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flatlander said:
I thought I was loosing my mind when I read through the draft and comments. Really tough to sort through in my opinion.
If this is truly their opinion to delete the matched device system then I don't understand why they left in the exception for a Mettalic raceway.

This is so crazy to think that any old listed breaker will do.
how does this arc fault protect the romex between panel and first outlet.

This is just backwards.

why not just.do away with them altogether. We all think they are a nuisance anyway.
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You want to know what the CMPs don't want you to know? A "parallel arc fault" is nothing more then a short circuit. Im not kidding, Im serious. This all got started when someone said that when a breaker does not trip magnetically on a fault it will result in a fire. I still have to see the evidence to back that one up. But it sure looked good in the eyes of marketing.
 
And unless I missed something in theory classes, wouldn't a series fault be detected as long as the device doing the sensing is anywhere in the series of the current that is flowing through the fault?

This leaves us with about the only series fault not to be sensed by a device at first outlet is either a loose connection at either end of the "home run" or damage has occurred within the "home run" that creates a series fault.
 
kwired said:
And unless I missed something in theory classes, wouldn't a series fault be detected as long as the device doing the sensing is anywhere in the series of the current that is flowing through the fault?

This leaves us with about the only series fault not to be sensed by a device at first outlet is either a loose connection at either end of the "home run" or damage has occurred within the "home run" that creates a series fault.
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Series arc fault need AFCIs to be detected because the current is often below 20amps limited by the loads on the circuit, however a parallel arc fault pulls as much current as the circuit allows. The 75 amp threshold came from what is believed to be the lowest short circuit value which can be found on resi wiring.
 
So we just pray that a series arc does not occur on the home run.
How Frikin ridiculous for professional technical people.
I remember the first ads for afci. The pictures depicted a nail in a wire causing a series fault. So we just hide under a rock and say home runs don't get hit by nails. Are they for real.

I hate Afci but this reasoning is nauseating.
 
flatlander said:
So we just pray that a series arc does not occur on the home run.
How Frikin ridiculous for professional technical people.
I remember the first ads for afci. The pictures depicted a nail in a wire causing a series fault. So we just hide under a rock and say home runs don't get hit by nails. Are they for real.

I hate Afci but this reasoning is nauseating.
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It has never been proven that a "series arc" tripping a breaker thermally results in fire. But that idea sure was pushed around:

http://paceforensic.com/pdfs/newsletter/KeepingPace-7.pdf

http://paceforensic.com/pdfs/newsletter/KeepingPace-37.pdf

http://paceforensic.com/pdfs/newsletter/KeepingPace-15.pdf


http://paceforensic.com/videos
 
flatlander said:
I thought I was loosing my mind when I read through the draft and comments. Really tough to sort through in my opinion.
If this is truly their opinion to delete the matched device system then I don't understand why they left in the exception for a Mettalic raceway.
Click to expand...

I think this is a maneuver to force AFCI into use in existing dwellings with fuse centers, without mandating replacement of overcurrent protection with circuit breakers, thus reducing the financial penalty to the home owner for, say, adding a circuit for a space heater / AC for an elder in one's care, or all sorts of other financial hardship examples.

Think about it a second. In an existing shack, I can add an Outlet Branch Circuit AFCI device in a box connected to a fuse center using a rigid offset nipple, and then run NM-B for all the rest of the new branch circuit.

And the 2017 NEC second revision prelim 210.12(A) (7) says that fuse / OBC AFCI equals the protection of a Combination-type AFCI, or other variations also spelled out.

It seems, in the numbering of the entries on Page 67 of http://www.nfpa.org/Assets/files/Abo...C_SRprelim.pdf that additional editing will occur, to tighten up the actual-to-be-published-numbering of the text, so I may be wrong.
 
flatlander said:
May have been a parallel arc when the nail tripped the breaker the first time. After resetting the breaker on a blasted wire it now becomes a potential heated section of wire or a series arc. Seen it too many times to count on my hands.
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Did the breaker trip after you reset it? How long did it take? Did a fire ensue?
 
flatlander said:
May have been a parallel arc when the nail tripped the breaker the first time. After resetting the breaker on a blasted wire it now becomes a potential heated section of wire or a series arc. Seen it too many times to count on my hands.
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Also, I disagree, a series arc can only take place of the conductor is completely broken (severed).
 
I'm sure it reset fine as it was back on in these instances. How many time has someone put a nail in a wire and tripped a breaker , reset the breaker and walked away?
Now you have a thinner section of wire heating the surrounding area.
Do these conditions lead to fire.
Don't know. I have seen scorched wood in a situation that is
30 years old. One instance a #8 aluminum reduced to about a 12. And still working.
 
flatlander said:
How many time has someone put a nail in a wire and tripped a breaker , reset the breaker and walked away?
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:D
Brings to mind the Master who taught me. He'd have two guys device everything while he, or another, would make up the panel. At the end, devicing done, the breakers were turned on.

He explained, earnestly, that once in a while a breaker would blow back but, upon turning it back on, it would hold and he'd never get a call back. He'd never investigate, unless it kept tripping.

He's retired now, after a long successful career, sold the business to his son, and it just keeps growing.

I still imagine those fireballs. . . somewhere in the house. . .
 
flatlander said:
I'm sure it reset fine as it was back on in these instances. How many time has someone put a nail in a wire and tripped a breaker , reset the breaker and walked away?
Now you have a thinner section of wire heating the surrounding area.
Do these conditions lead to fire.
Don't know. I have seen scorched wood in a situation that is
30 years old. One instance a #8 aluminum reduced to about a 12. And still working.
Click to expand...

Did the breaker trip thereafter being reset?

Id argue in most cases it just trips the breaker. But, ok, we want all installations to be covered and not gamble due to limited evidence. In all these cases the EGC is involved, so GFP does the same with 100% reliability. Still do not see the whole need for arc signature yada, yada.
 
al hildenbrand said:
:D
Brings to mind the Master who taught me. He'd have two guys device everything while he, or another, would make up the panel. At the end, devicing done, the breakers were turned on.

He explained, earnestly, that once in a while a breaker would blow back but, upon turning it back on, it would hold and he'd never get a call back. He'd never investigate, unless it kept tripping.

He's retired now, after a long successful career, sold the business to his son, and it just keeps growing.

I still imagine those fireballs. . . somewhere in the house. . .
Click to expand...

Probably an EGC touching a device screw. Current blows a chunk out of the EGC and screw... presto you now have air between the two points :thumbsup:


There is one thing AFCI (at least the 30/50ma GFP) have caught and that would be sloppy electricians.
 
The development of 2017 NEC is far from being complete, so I wouldn't get too worked-up over the Second Draft Reports. Receipt for recirculation of voting doesn't occur until January 22, 2016. The Correlating Committee doesn't meet until February. Things can change!

NITNAM filings are accepted until April 29, 2016. Assembly voting occurs at the annual meeting in June. And, appeals can be submitted as late as July 2016.

So, a lot can happen between now and the publication of the 2017 NEC.

This may even be an issue that gets a TIA issuance...

So, stay tuned!
 
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