Question from UL about AFCI breakers.

[bphgravity]

Good Morning Everyone,

Please see the question below posed by Mr. Fecteau of UL.

I have not had any personal experience nor have received any reports of an AFCI breaker actually functioning properly due to a real arcing / faulting condition. I can say that I have first hand knowledge of AFCI tripping due to unintentional ground faults located somewhere on the protected circuit. The far majority of the cases resulted from the equipment grounding conductor coming in contact with the grounded (neutral) terminal of a receptacle. I can say without a doubt that particular aspect of the device works. These were conditions that may have gone unnoticed on a regular overcurrent device.

Since the adoption of the 2002 NEC here in Florida, I would rate the number of troubleshooting issues / complaints about AFCI’s in this order:

1. Defective device
2. Nuisance appliance tripping (vacuum cleaners / UPS’s / refrigeration equipment)
3. Unintentional Ground-faults.


If you have any positive accounts or reports, please feel free to respond directly to Mr. Fecteau.


Thank you,




Bryan Holland


________________________________________
From: Jeffrey.Fecteau@us.ul.com [mailto:Jeffrey.Fecteau@us.ul.com]
Sent: Tuesday, July 12, 2011 5:22 PM
Subject: AFCI ?

I am looking for any first hand experience where an AFCI worked. We have all heard stories of nuisance tripping, but what I am looking for is information on where the AFCI performed properly. For example, an actual arc fault or damaged conductors that had a potential to start a fire.

If you have any stories or information, I would like your permission to possibly quote you in an article.

Thanks


Jeffrey A. Fecteau C.B.O., E.C.O
Lead Regulatory Engineer
Regulatory Services
Underwriters Laboratories

 

[George Stolz]

My hopes were elevated for a moment, until I realized that the UL would likely not pressure a manufacturer and the NFPA to give up on AFCI's. Everybody has money to be made on this.

 

[sgunsel]

You could say the same for just about everything in the NEC. Coat hangers with newsprint insulation (if you want to be elaborate) could be used for wiring and could be made to work, and probably cheaper than NM or all that other manufactured stuff.

A friend of mine had his house catch fire and it would have been prevented by an AFCI. Unfortunately, it looks to me like the biggest beneficiaires of AFCIs are owners of older houses and they are exempt.

 

[kwired]

A friend of mine had his house catch fire and it would have been prevented by an AFCI.

I assume that would be true if the AFCI actually does what manufacturers claim they are supposed to do. The topic of this thread is questioning that claim.

 

[renosteinke]

I think it's a fair request, and I'm astonished that someone at UL is even asking the question.

Imagine if we passed a law against martians opening donut shops on the moon. It's a good practice to limit your laws to addressing issues that REALLY exist - and the question posed asks whether there is any evidence that the 'problem' that AFCI's solve really exists.

After a decade in existence, someone ought to have been able to document a 'save' by an AFCI. As in: "I replaced the obviously faulty AFCI with a regular breaker, and two days later the attic caught fire. Oops."

There's also the matter of testing AFCI's, and UL's position regarding proprietary technology. Simply put, UL will not be party to the game where someone manipulates codes for financial gain. That's why UL insisted that the AFCI patents be 'public domain' before writing a standard. Since then, there's been plenty of 'proprietary arc' silliness regarding the testing of AFCI's, and I can tell you right off that such talk does not sit well at UL. I mean, how can you tell that the 'test' button isn't simply an 'off' switch?

Contrast this with GFCI.s where UL heartily endorses the use of separate testers to check for GFCI protection.

I note the UL quote refers to nuisance trips caused by vacuums, etc. I find this fascinating - since NEMA and the AFCI makers have taken the position that there has NEVER been a documented instance of a properly functioning, listed appliance causing a false trip of an AFCI. Perhaps that claim make some folks sceptical - after all, can you think of anything else that has a perfect record?

Back when aluminum wiring was in fashion, there was no shortage of incidents where fires occurred and aluminum was present. Were AFCI's the salvation they are portrayed as, we ought to have -by now- quite a collection of stories where the lack of AFCI's allowed bad things to happen. We ought to be able to point to examples where a 'malfunctioning' AFCI was replaced, only to have bad things happen.

 

[kwired]

I have said this before. The only way we will really know if AFCI's do what the manufacturers claim they will do is when or if insurance companies recegnize that they have less claims as a result of electrical fires and offer lower rates for homes that have AFCI's installed. I still think it will be many years before that will happen, if it happens.

How many AFCI's do you suppose are removed by either the HO or a handiman because they are tired of them tripping for no apparent reason? While they are at it, why not make it a 30 amp breaker so there is even less chance of it tripping?

 

[don_resqcapt19]

... Were AFCI's the salvation they are portrayed as, we ought to have -by now- quite a collection of stories where the lack of AFCI's allowed bad things to happen. We ought to be able to point to examples where a 'malfunctioning' AFCI was replaced, only to have bad things happen.

Not sure we would have very many examples. Using the same fire cause data that was used to show the need for AFCIs and assuming 100% compliance with the 2008 code starting 1/1/08, you could only expect that AFCIs would have prevented ~625 dwelling unit fires to date. That is also assuming that the AFCIs are 100% effective in doing what they say they do.

 

[renosteinke]

Thanks for the number crunching, Don ... but ...

By golly, the AFCI has been required since the 99 code. OK, there have been all manner of changes, but there ought to be SOME sort of track record.

 

[ELA]

Another way we will know if AFCI's do what the manufacturers claim they will do is when Fire Inspectors have to stop blaming an "unknown cause" for fires, on Electrical :roll:

 

[don_resqcapt19]

Thanks for the number crunching, Don ... but ...
By golly, the AFCI has been required since the 99 code. OK, there have been all manner of changes, but there ought to be SOME sort of track record.

Between the 99 and 2008 code it was a really small number of fires that would have been prevented as the AFCI protection was limited to bedroom branch circuits and as I recall less than 10% of the fires said to be of electrical origin started in bedrooms. I did the same type of numbers for that application, but I don't have them any more. As I recall the numbers I did for the first year after they required the bedroom receptacle and lighting branch circuits to have AFCI protection showed that we could expect to prevent 7 fires in that first year.

 

[jumper]

Between the 99 and 2008 code it was a really small number of fires that would have been prevented as the AFCI protection was limited to bedroom branch circuits and as I recall less than 10% of the fires said to be of electrical origin started in bedrooms. I did the same type of numbers for that application, but I don't have them any more. As I recall the numbers I did for the first year after they required the bedroom receptacle and lighting branch circuits to have AFCI protection showed that we could expect to prevent 7 fires in that first year.

Here is your proposal with the numbers:

2-122 Log #1878 NEC-P02
(210-12)
Final Action: Reject
Submitter: Donald A. Ganiere Ottawa, IL

Recommendation:
Delete this section.

Substantiation:
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 shows 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. 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 GFCI data and new GFCI standard seems to indicate that they won't be function 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??

The above figures are based on AFCIs preventing 40% of the bedroom electrical fires, but even if we assume that the AFCIs would be 100% effective, the ten year cost would still be more than $667,000.00 per fire prevented. Again I ask, is this a reasonable cost/benefit?

Panel Meeting Action: Reject
Panel Statement:
See the panel action and statement on Proposal 2-116 (Log #452). The economic information provided in the substantiation is of a general nature and the data cited has not been substantiated. The panel has reviewed the analysis and finds that there is no data provided on loss of life or personal injury and the panel has not attempted to place a monetary value on the loss of life or personal injury.
Number Eligible to Vote: 13
Ballot Results: Affirmative: 11 Negative: 2
Explanation of Negative:
BECKER: See my Explanation of Negative on Proposal 2-116.

DOBSON: See my Explanation of Negative on Proposal 2-116.

 

[don_resqcapt19]

Thanks Derek,
I had forgot about that proposal.

 

[ptonsparky]

The first afci I ever put in tripped. Found a string of chistmas lights plugged in with one of the lamps broken. They were laying on or under a bean bag chair I believe. Not sure if it tripped on overcurrent or arc fault. It was not scientifically repeatable so it doesn't count for diddly.

 

[Buck Parrish]

.

A friend of mine had his house catch fire and it would have been prevented by an AFCI. Unfortunately, it looks to me like the biggest beneficiaires of AFCIs are owners of older houses and they are exempt.

That must be a local amendment to the code.


Not braggin, but we just used 40 in four houses and never had one nusiance trip. I thought may be they were making them less sensitive. Or may be its just the guys are getting better at not letting the neutral touch the grounding conductor.

 

[Twoskinsoneman]

That must be a local amendment to the code.


Not braggin, but we just used 40 in four houses and never had one nusiance trip. I thought may be they were making them less sensitive. Or may be its just the guys are getting better at not letting the neutral touch the grounding conductor.

Not a local amendment just a fact that they didn't exist or weren't required back when the older homes were built.

 

[Buck Parrish]

Not a local amendment just a fact that they didn't exist or weren't required back when the older homes were built.

I think he meant todays older homes. As an older home when built would have been a newer home.

Besides those soldered joints would not arc much Its when the old circuits are modified that causes problems. (IMHO)

 

[renosteinke]

"A friend of mine had his house catch fire and it would have been prevented by an AFCI."

Well, that's a start ... but to 'count,' we need a wee bit more, we need one more step to be taken.

That is, we need to show that an AFCI did trip, did prevent a problem. That's what we're looking for. The problem also has to be one that would not have tripped a conventional breaker or GFCI.

That's the problem with the Christmas light example; woul the problem have also tripped an ordinary breaker?

That's why I suggested we look for an instance where a tripping AFCI problem was 'fixed' by replacing the AFCI with an ordinary breaker- and there then being evidence found of an arcing problem. It need not be an actual fire; scorch marks and broken conductors would qualify. Even just hearing the popping sound (in a fixture, for example) and a slight smoke odor will do. Then, when the problem is fixed, we return the AFCI to the circuit and it no longer trips.

That's the sort of story we need to hear.

 

[nascar03]

AFCI? They do work.

AFCI? They do work.

I assume that would be true if the AFCI actually does what manufacturers claim they are supposed to do. The topic of this thread is questioning that claim.

AFCI in bedroom would trip occassionally. troubleshooting led to the afci tripped when the ceiling fan in my daughters bedroom was on and had been running for a while. fan was pulled down and it was found to be the conductor feeding the lights had not been tied up properly and when the fan was put in place, it allowed the conductor to rub on the fan motor body. it had rubbed through the insulation and when the fan vibrated just right, it would arc and trip the afci. And yes we did swap out the breaker for a standard one and it didn't have enough current flow to ground to trip, but it would and did trip the AFCI. So, i say they work as designed.

 

[kwired]

AFCI in bedroom would trip occassionally. troubleshooting led to the afci tripped when the ceiling fan in my daughters bedroom was on and had been running for a while. fan was pulled down and it was found to be the conductor feeding the lights had not been tied up properly and when the fan was put in place, it allowed the conductor to rub on the fan motor body. it had rubbed through the insulation and when the fan vibrated just right, it would arc and trip the afci. And yes we did swap out the breaker for a standard one and it didn't have enough current flow to ground to trip, but it would and did trip the AFCI. So, i say they work as designed.

That could easily trip a GFCI also and will likely trip at a lower fault level than the AFCI. The fault current is flowing outside the line to neutral path. How do you know the ground fault component of the AFCI breaker was not what was causing the tripping?

 

[tom baker]

Between the 99 and 2008 .

Wasn't it the 05 code with a Jan 1 2008 start date?
Sorry Don I couldn't resist as you are always spot on for your code information.