info on arcing-fault brakers

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Old 11-10-02, 10:57 PM
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info on arcing-fault brakers

Hi everybody,im wondering if someone knows from practical experience if arcing -fault detection brakers REALLY work and PROTECT houses from fires,also can this devices be adapted to work in a fused circuit
tnx a lot papi
 
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Old 11-11-02, 05:49 AM
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Arc Fault breakers do protect in a different way than a standard breaker, GFCI breaker and a fuse. The jury is out regarding how much of an actual difference it will make.
If it means anything, the 2002 national electric code requires arc fault breakers on all bedroom circuits.
To use these breakers in a fused panel arrangement, you will have to install a sub-panel with breakers from fuses in your existing panel.
 
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Old 11-11-02, 08:12 AM
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An interesting article appeared today from Don Ganiere in the Mike Holt newsletter talking about the practical benifits verus cost I will try and insert it here for you to take a look at

"I still find it very strange that the AFCI requirement was put into code without any statements saying how many fires these devices would be expected to prevent. Where is the cost benefit study? We will never have the technology to make our electrical systems safe and even if it was physically possible to make them 100% safe, it would not be economically possible.

I have worked up some fire data numbers using information from "Fire in the United States, 12th Edition". http://www.usfa.fema.gov/downloads/p...s/fius12th.pdf This is 1998 data. The numbers in this report are based on NFIRS (National Fire Incident Reporting System) data. The NFIRS data accounts for 39% of all fires that occur in the US. I have adjusted the numbers by this factor to account for all fires.

This data shows that there were 401,695 residential unit fires in the US in 1998. The point of origin for 12.9% of these fires was the sleeping room. Of the fires that originated in the sleeping room, 19.9% were reported to have been caused by the electrical distribution system and 11.6% by appliances. Applying these percentages to the total number of residential unit fires shows that 51,819 fires originated in the sleeping room. Of these 51,819 fires, 31.5% were caused by the electrical distribution system or appliances. This would mean that 16,323 dwelling unit fires may have been electrical in origin.

Mr. Robert Clarey of Cutler-Hammer made the statement that AFCIs could be expected to prevent 40% of these fires. This statement was made in comment 2-68 in the '98 ROC. This means that if every dwelling unit bedroom branch circuit in both new and existing dwelling units had AFCI protection, we would prevent 6529 fires per year.

We now have to look at the total number of dwelling units existing in the US and the number that are added each year. US Census data show that there were 115,253,000 housing units in 1999. 1,640,900 new housing units were built in 2000. If you divide the 6529 dwelling unit fires that would be prevented if all dwelling units had AFCIs by the total number of existing housing units and then multiply that result by the number of new housing units being built, we can expect that 93 dwelling unit fires would be prevented the first year of full compliance with the AFCI rule.

Note: This number is high as fires do not occur nearly as often in new buildings. The fire data used to get the AFCIs into the code showed that 85% of the electrical fires originated in dwelling units over 21 years old. This 85% electrical fires occurring in dwelling units over 21 years old data is from the 1987 Consumer Products Safety Commission report titled, "Residential Electrical Distribution Systems Fires". This data was cited in comment 2-63 in the 1998 ROC.

This brings up the additional question of whether the AFCI breaker will still be functional, when it its needed, over 10 years after its installation. The NEMA Study (http://www.mikeholt.com/htmlnews/afci/GFCInema.pdf) seems to indicate that many will not be functioning at that time.

If we assume an installed cost of only $75 per new dwelling unit, that means that we would be spending $123,067,500.00 per year to install AFCIs in each of the 1.6 million new dwellings. The $75 assumes an average cost of $40 per AFCI, an average of 1.5 AFCIs required per dwelling unit, and $15 for additional labor and material that may be required such as two runs of 12-2 in place of a single run of 12-3.

If we adjust the number of fires that will be prevented by the use of AFCIs for the 15% of electrical fires that occur in dwelling units 10 years or less in age, we find that in the first year of compliance we would expect to prevent 14 fires. The cost of preventing these fires this first year would be over 8.7 million dollars per fire!

Each successive year of full compliance will result in additional fires prevented in the dwelling units that are constructed each year as well as those prevented by the previous year(s) AFCI installations. Even we these additional prevented fires are factored in we still don't have a reasonable cost benefit. At the end of 10 years, the cumulative AFCI installation cost will be over 1.2 billion dollars and the total number of fires prevented will be less than 750. The cost per fire prevented over the 10 years is still over 1.66 million dollars! Is this a reasonable cost/benefit??"

These are Don Ganiere facts and figures I have not done any checking into them as I have just seen this for the first time this morning. but it does make sense
 
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Old 11-13-02, 06:58 AM
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How much is your life worth? Can you put a price on your life or your children’s lives? I am VERY experienced with AFCI's. I am not affiliated with any AFCI manufactures, but I have tested all of them in a lab situation. The current AFCI technology is not all that good at all. It really only protects against high current parallel arcing or arcing to the ground wire. This makes no sense because by the time you get a high current arc, hot sparks are already flying. They are significantly safer then normal breakers, but there is much room for improvement. The biggest problem with them is that they do not detect series arcs due to loose terminals, wire nuts, and broken wires. Soon enough you will see AFCI’s that detect all arcing. The UL requirements are getting more stringent due to industry concerns. If you have seen first hand some arcing faults with and then without even the current AFCI technology, you would be lining up to pay $75 for safety.

I am in no way trying to sell these things. I am just trying to share my experience. I believe that when this technology evolves people will buy them because they save lives, not because some corperate big wigs pushed a requirement into the NEC.
 
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Old 11-13-02, 07:29 AM
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Homer your raise some valid points unfortunatly I have not seen the tests you have so I can only go on what I've read and what is put in front of me I understand many people are changing their veiws on these devices every day. But I still would of liked a little more study done on them before having them rammed down our throats. One life is worth a lot but I think there are a lot of misconceptions about them and they should be addressed by the NEC, UL and the manufacturers. Explain and provide the backup for the decision.
 
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Old 11-13-02, 08:13 AM
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I agree

I definitely think that it was premature to require the use of these limited function devices. If they where able to detect all arcing then I could see it, but we are not at that point yet. I believe the manufactures are screwing themselves because there is so much opposition due to the AFCI’s limited capabilities. I will not be suppressed if the requirement is dropped during the next NEC cycle.
 
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Old 11-14-02, 11:55 PM
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Tnx very much all for the excelent info and exchange of opinions.
My personal interest about this devices is that i live in a house that has knob and tube wiring.I have been very concern about the risk of fire.
I have got from this forum great support at diferent times i asked i question for i m really greatful to all those that shared their expertice.

I m having some dificulties trying to rewire the house while wating for surgery and i thoght that by installin these brakers i would buy some peace of mind until spring reducing the risk of fire by how much? i was hoping to hear that they would provide 100% protection,i see this is not the case.

The circuits for the hot water tank, oil furnace,all of the basement and part of the kitchen are not more than a few years old and done with modern wires,however my worries come from two other circuits that feed all lights and plugs in three bedrooms,two stair cases,living LIGHTS[ABOUT 10 PLUGS AND 10 LIGHTS all together]this two are the KNOB AND TUBE that i was hoping to pospone the rewiring for a while and be protected with the arc fault brakers. The knob and tube wiring LOOKS in good shape but i cant see behind the walls.
As measure of prcaution all light bulbs have been replace with new fluorescent low wattage and there are nor oveload circuits,but im still worried Thank you all again for caring

regards papi
 
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Old 11-15-02, 06:01 AM
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Knob and tube wire is one of my main areas of concern with current AFCI technology. AFCI breakers do not detect low current arcing or series arcs, without the presence of the ground wire. They rely on the fact that a break in the ungrounded conductor will eventually cause arcing to the bare ground wire in romex cable. Without the ground wire, AFCI's will only protect against high current arcs, like a short circuit. That is why it is pointless to use them for two wire systems, like knob and tube. Also, many knob and tube circuits have shared neutral wires. You may find several circuits with only one neutral return wire. This will cause the AFCI to false trip constantly.
It sounds like you have done all that you can for safety already. Just make sure that you have the correct size fuses or breakers. My house has the same setup, with outlets added to the old lighting circuit. Because of this, some people may use bigger fuses for the increased load.
 
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