This thread “degenerated” into a discussion of Arc Fault Circuit Interrupters.
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=81674.1&maxT=1
I found this article that defines the types of Arc fault circuit interrupters (AFCI).
– Branch/Feeder AFCI – This device is installed at the origin of a branch circuit
or feeder, such as at a panelboard, to provide protection of the branch circuit
wiring, feeder wiring, or both, against unwanted effects of arcing. This device
also provides limited protection to branch circuit extension wiring (e.g. cord
sets and power supply cords). These may be a circuit-breaker type devices
or a device in its own enclosure mounted at or near a panelboard.
– Outlet Circuit AFCI – This device is installed at a branch circuit outlet, such
as at an outlet box, to provide protection of cord sets and power-supply cords
connected to it (when provided with receptacle outlets) against the unwanted
effects of arcing. This device may provide feed-through protection of the cord
sets and power-supply cords connected to downstream receptacles.
– Combination AFCI – This is an AFCI which complies with the requirements
for both branch/feeder and outlet circuit AFCIs. It is intended to protect
downstream branch circuit wiring, cord sets and power-supply cords.
There is also a separate type of device that goes on the end of supply cords. They are being used on new window AC units.
AFCI’s have a fault current detection function. It is similar to GFCI’s except that it set for 30 ma and the purpose is to detect failing insulation and not personal protection.
The other feature is arc detecting. There are two types. Series and Parrallel.
The branch feeder type of AFCI’s only detect parallel types of arcs at a level of 75 amps. Note. Although the spikes of the current is 75 amps the average is low enough that it won’t trip on an overload.
The outlet type of AFCI is suppose to detect arc fault of 5, 10, and 150% of load arcs. I am not clear if that is series or parallel arc. This is representative of arcing in a cord or at the plug/receptacle. Where as the 75 amp arch is representative of problems in the house wiring.
The combination type means that it can detect both type of arcing.
This article was printed in 2003 while the 2005 NEC was being prepared.
http://www.iaei.org/subscriber/magazine/03_f/03_f_brendanfoley.htm
At that time there was discussion of requiring a combination type of AFCI.
It is really blistering against it.
” Experience with Combination AFCIs
Combination AFCIs have been UL listed by three companies, Pass & Seymour Legrand, HETKO and Square D. The Pass & Seymour Legrand device was listed in 1999,9 the HETKO device was listed in the first quarter of 2003, and the Square D AFCI was listed in August/September of 2003. None are commercially available. It must be noted that the detection of low current arcs by combination AFCIs necessitates technology that is capable of distinguishing, on a continuous basis, between damaging arcs and the safe arcs and transient waveforms associated with everyday circuits. Thus there are safe arcs associated with motor brushes (for example, vacuum cleaners), with switches (for example, light controls, hairdryers, etc.), with bi-metal temperature controls of household appliances (for example, irons). Further, there are chopped waveforms associated, for example, with electronic power supplies (computers, lamp ballasts, etc.).”
As they finally released it the 2005 NEC requires the branch-feeder AFCI to be used for bedroom circuit until 2008. It is not clear, but I think that after that time the combination type be used.
The PROPOSED 2008 NEC requires COMBINATION type AFCI’s on ALL 15 and 20 amp, 120v circuits in residents.
Replies
I didn't see this post this morning !
I found the definition over at UL .....
http://www.ul.com/regulators/afci/categories.cfm
.....this is iaei from their website, it would seem that CMP-2 is going to have to consider widening 210.12
..." Expansion of AFCI
The proposals to expand coverage to locations beyond dwelling unit bedrooms included a number of prospective areas:
· All circuits in dwelling units
· All living areas in dwelling units
· Dormitories
· Assisted living units and nursing homes
· Day-care facilities "
even though the latest generation of the device has a few flaws in it
it is obvious this could be very lucrative for mfrs. so much that HETKO (korea) wants on the bandwagon..
big $$$ figures have been used to show why these things ARE necessary...from the CSPC
fortunately, ROP 2008 is available for reading in .pdf
but at 998 pages I don't have the patience to look for proposals to 210.12
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.Wer ist jetzt der Idiot
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Edited 11/19/2006 10:54 am by maddog3
Well the copy that I have shows only 802 pages.But here is the main part of the text.(B) Dwelling Units. All 120-volt, single phase, 15- and
20-ampere branch circuits installed in dwelling units shall
be protected by a listed arc-fault circuit interrupter, combi-nation
type installed to provide protection of the branch
circuit. [ROP 2û105, 2û142, 2û111]Really just what I had summerized.I have no idea how these are handled. If they update the whole thing from time to time or if a working group works on different sections and it is only when it is time to put the new version together does everything get reviewed.
public Proposals are accepted until
Nov, 4 '05 by 5 P.M. ESTthere are meetings in Jan. and Apr.the Report of Proposals (ROP) is made public after
July 14 ' 06then comments (Receipt of Comments) are accepted until
Oct.20 '06 by 5 P.M. ESTthe Code Making Panels meet to discuss the comments from
No.28- Dec.9 ' 06there are Correlating Committee Meetings from
Feb 19 - 23 ' 07Reports of Comments(ROC)are made public after
Mar. 23 " 07Standards Council Issuance takes place
July, 2007.
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.Wer ist jetzt der Idiot
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Because I was wiring my own house and saving some dough, I decided to fork out for a bunch of AFCIs. As a result, every recep in the house is protected by either GFI or AFI. The inspector warned me about nuisance trips, but after two years of living here, there hasn't been a single problem.
I can see the day when it will be a code requirement. If they save lives, add little cost, and aren't a nuisance, why not?
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
do you test them? regularly?
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.Wer ist jetzt der Idiot
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>>>do you test them? regularly?
Ah, sure, ya really,.....
Well, Ok, once every few months. I don't have the fancy hand unit. I just press the button on the breaker.
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
"As a result, every recep in the house is protected by either GFI or AFI."Why not both?They are really two different things. And if things that the AFCI adds real protection then why aren't you also protecting all of the circuits, even those with GFCI?And by the way you don't have a combintation type of AFCI.Don't know if there are any commercially available yet. Those are the ones that will really be prone to false tripping."It must be noted that the detection of low current arcs by combination AFCIs necessitates technology that is capable of distinguishing, on a continuous basis, between damaging arcs and the safe arcs and transient waveforms associated with everyday circuits. Thus there are safe arcs associated with motor brushes (for example, vacuum cleaners), with switches (for example, light controls, hairdryers, etc.), with bi-metal temperature controls of household appliances (for example, irons). Further, there are chopped waveforms associated, for example, with electronic power supplies (computers, lamp ballasts, etc.)."
>>>Why not both?
>>>They are really two different things.
Yes, I'm aware of the difference, although probably not to the technical depth that you are. Fact is, I had to draw the line somewhere, and I figured I could always go back to add AFI breakers on circuits with inline GFIs when the prices come down and performance goes up.
...Plus I didn't want to give the inspector something to sneer about. Our's makes life difficult enough for HOs as it is....
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
I'll never put AFCI's in my house. If somebody puts them in, I'll remove them.
We was in a condo in Las Vegas, very dry climate. Every time you walked across the rug in the bedroom and touched a lamp, the AFCI would blow and all of the lights in the bedroom would go out. Had to reset the breaker. LOL.
We are fairly dry in Kansas, don't need the nuisance.
Ozlander
so you test them....good......now , can you tell me what wiring is protected by an AFCI breaker ?hint: it ain't the table lamp or the clock on the nightstand
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.Wer ist jetzt der Idiot
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>>>can you tell me what wiring is protected by an AFCI breaker ?
Anything that could develop an arc: extension cords slammed in doors or under rugs (oops), loose wire nuts, poorly secured plug terminals, old receps with tired contacts..... etc.
Is that what you asked?
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
"Anything that could develop an arc: extension cords slammed in doors or under rugs (oops), loose wire nuts, poorly secured plug terminals, old receps with tired contacts..... etc."Most of those are low current series arcs and would not be detected by an AFCI.
>>>Most of those are low current series arcs and would not be detected by an AFCI.
Huh? An unknown load plugged into a squashed extension cord cannot be assumed to be low current or in series.
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
The load should be a maximum of 15 amps.And in most cases any fault would be series.The current AFCI will only detect parallel arcing of 75 amps.Now if you have a heavy duty expension cord with both hot and neutral (or ground) exposed then you might get shorting arcing high enough to trip it.But most cases will be series arcing and at a realatively low current level depending on the load.
>>>The current AFCI will only detect parallel arcing of 75 amps.
See, I knew you had a better technical understaning than I. I'll have to do some reading on this issue.
At a limit of 75 amps parallel, it's no wonder that I don't have any nuisance tripping; I do tight wiring and I practice basic electrical safety. It also makes me wonder what the heck is happening with those that complain of nuisance tripping...
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Bill, can you give us all a differentiation between parallel and series arcing? Where and why would these commonly occur?
Thanks. Your elec. posts are always interesting to me. Seriously. I'm not just sucking up!
"Thanks. Your elec. posts are always interesting to me. Seriously. I'm not just sucking up!"Cash works better than sucking up.Thanks."Bill, can you give us all a differentiation between parallel and series arcing? Where and why would these commonly occur?"Now, I don't know exactly what the background is on all the AFCI designs and testing. So I might have it exactly correct.A parallel arc is when you have connection between the hot and neutral or ground. This requires a failure of the insulation on the hot wire and also on the neutral/ground unless it fault to a bare ground.Most residential wiring today is romex and plastic boxes. That leaves very few ways that you can get a parallel fault. One possiblilty would be a nail through a cable. Another would be a stapple that is over driven and cuts through the sheath and the wire insulation.Romex with metal box and AC cable have more places where they can parallel arc.With a parallel arc the current flow goes from zero or whatever load there was towards infinity. If it was a dead short the breaker would quickly trip. But with any arcing fault the connections "burns out" (creating heat) and goes back to normal and then repeats.A series arc is when you have something in series with the flow of current that is failing. In that case the current flow goes from whatever the load is to towards zero. Then the connect is remade and current flow resumes. Each time that the connection is made and released arc forms and heat is generated. Also when the connection is remade it is often not a solid connection so there is more resistance and more heating.Many places for a series arc. Bad wire nut connection. Backstab connections. You can also have it under a screw terminal connection, but that is very rare. Loose plug to receptacle connection. Broken wires in a power cord, specially where it connect to the plug.I have absolutly no data to back this up, but I suspect that series arcing is much bigger problem. Many be an order or two of magnitude.