After atending a Mike Holt seminar the topic of arc falt breakers came up and he stated that the arc falt breaker would protect a recptical with a loose screw (conection) arcing ? would the receptical have to melt before tripping the breaker ?
AFCI BREAKER
- Thread starter domnic
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allenwayne
Senior Member
Re: AFCI BREAKER
Last week I went to a home that one of our trim crews had been hotchecking.In master bedroom a drywall nail had penetrated a 3 wire cable assy. for a switched receptacle,it was touching the ground and the tip had barely penetrated the red, switched wire.AFCI had tripped several times as they troublshot the problem.When the drywall was cut away and the outer sheating was cut back we found there was no actual damage to the wire other than the pinpoint penetration in the insulation.If this was anything other than an AFCI circuit the arching would have burnt the affected wire,but as an afci circuit it did what it was designed to do.So I don`t think a receptacle would melt before an AFCI trips.
Last week I went to a home that one of our trim crews had been hotchecking.In master bedroom a drywall nail had penetrated a 3 wire cable assy. for a switched receptacle,it was touching the ground and the tip had barely penetrated the red, switched wire.AFCI had tripped several times as they troublshot the problem.When the drywall was cut away and the outer sheating was cut back we found there was no actual damage to the wire other than the pinpoint penetration in the insulation.If this was anything other than an AFCI circuit the arching would have burnt the affected wire,but as an afci circuit it did what it was designed to do.So I don`t think a receptacle would melt before an AFCI trips.
charlie
Senior Member
- Location
- Indianapolis
Re: AFCI BREAKER
The AFCIs of today will protect the wiring but will not protect cords. It will take 75 amperes before an AFCI will react to a fault and it will not detect a loose connection yet, the type required to be used on January 1st, 2008 will be required to protect against loose connections and cords.
The AFCIs of today will protect the wiring but will not protect cords. It will take 75 amperes before an AFCI will react to a fault and it will not detect a loose connection yet, the type required to be used on January 1st, 2008 will be required to protect against loose connections and cords.
Ed MacLaren
Senior Member
Re: AFCI BREAKER
These things must be really intelligent, if they can determine the difference between the circuit conductor and the cord conductor.
I realize that the example below is over-simplified, but the fault current path is basically a series circuit.
The fault current will either be 75 amps or it won't be, no matter where the fault occurs.
What am I missing?
Ed
I've heard this statement many times, and from many sources, and can't help being a bit amused.
These things must be really intelligent, if they can determine the difference between the circuit conductor and the cord conductor.
I realize that the example below is over-simplified, but the fault current path is basically a series circuit.
The fault current will either be 75 amps or it won't be, no matter where the fault occurs.
What am I missing?
Ed
Re: AFCI BREAKER
When equipment is submitted for listing by a NRTL the test is specific.
Branch and Feeder AFCI protectors are tested with the in wall wiring. where the AWG is controlled and line resistance is predictable.
Beyond the face of the device is not under the control of the manufacture. I suspect that a series or parallel fault in 16 or 18 AWG SPT may cause current flow that is unpredictable.Also the AFCI in use today (not combination) also requires a ground fault to work, this would not be available with parallel cord.
75 A is the Average available fault current at the outlet (in Wall) according to the powers to be.
The new combination AFCI supposedly will react to fault current levels as low as 2 -5 A rather than 75A.
I don't know if this helps
Charlie
When equipment is submitted for listing by a NRTL the test is specific.
Branch and Feeder AFCI protectors are tested with the in wall wiring. where the AWG is controlled and line resistance is predictable.
Beyond the face of the device is not under the control of the manufacture. I suspect that a series or parallel fault in 16 or 18 AWG SPT may cause current flow that is unpredictable.Also the AFCI in use today (not combination) also requires a ground fault to work, this would not be available with parallel cord.
75 A is the Average available fault current at the outlet (in Wall) according to the powers to be.
The new combination AFCI supposedly will react to fault current levels as low as 2 -5 A rather than 75A.
I don't know if this helps
Charlie
- Location
- Illinois
- Occupation
- retired electrician
Re: AFCI BREAKER
Ed,
Many times the impedance of the small cords and equipment as well as that of the arc itself will limit the peak arcing current to a level far below 75 amps. You drawing shows a #12 cord. In my opinion it is a very rare dwelling unit appliance that has a #12 cord. Even 1750 watt heaters often have #16 cords.
Don
[ February 08, 2005, 06:46 PM: Message edited by: don_resqcapt19 ]
Ed,
Many times the impedance of the small cords and equipment as well as that of the arc itself will limit the peak arcing current to a level far below 75 amps. You drawing shows a #12 cord. In my opinion it is a very rare dwelling unit appliance that has a #12 cord. Even 1750 watt heaters often have #16 cords.
Don
[ February 08, 2005, 06:46 PM: Message edited by: don_resqcapt19 ]
- Location
- Illinois
- Occupation
- retired electrician
Re: AFCI BREAKER
Domnic,
Neither the current nor the new AFCIs directly protect against loose or high resistance connections. They clear this type of fault when one of two things happens...enough insulation melts to cause a parallel arcing fault, or enough melts to cause a ground fault. All AFCIs have a 30 to 50mA ground fault trip circuit. It is my opinion that this circuit trips the breaker most often. It is very difficult to create a parallel arcing fault without also creating a ground fault on any wiring system that includes an EGC. This is another reason why they provide limited protection beyond the fixed wiring system...not to many dwelling unit cord and plug connected items include an EGC in the cord.
Don
Domnic,
Neither the current nor the new AFCIs directly protect against loose or high resistance connections. They clear this type of fault when one of two things happens...enough insulation melts to cause a parallel arcing fault, or enough melts to cause a ground fault. All AFCIs have a 30 to 50mA ground fault trip circuit. It is my opinion that this circuit trips the breaker most often. It is very difficult to create a parallel arcing fault without also creating a ground fault on any wiring system that includes an EGC. This is another reason why they provide limited protection beyond the fixed wiring system...not to many dwelling unit cord and plug connected items include an EGC in the cord.
Don
Ed MacLaren
Senior Member
Re: AFCI BREAKER
But you know the point I was trying to make.
It is not accurate to say that an AFCI "will not protect cords".
It may not, and probably will not, but it possibly could.
Ed
I know. I exaggerated.
But you know the point I was trying to make.
It is not accurate to say that an AFCI "will not protect cords".
It may not, and probably will not, but it possibly could.
Ed
charlie
Senior Member
- Location
- Indianapolis
Re: AFCI BREAKER
Ed, build your cords with #12 or #14 with a grounding conductor or a braided shield and I will retract my statement.
Ed, build your cords with #12 or #14 with a grounding conductor or a braided shield and I will retract my statement.
- Location
- Illinois
- Occupation
- retired electrician
Re: AFCI BREAKER
Ed,
Don
Ed,
Yes, it could provide protection on the load side of the building wiring system. That is way I normally say that AFCIs provide only "limited" protection beyond the outlet.
Don
Re: AFCI BREAKER
The fact of the matter remains. The term arc fault is mis-leading in so much the these units are looking at a combination of circuit parameter.
as Don mentioned
Arcing arc signature
75 amp fault current
concurrent 30-50 mA fault to ground.
in fact a series arcing fault on a system that can not establish a ground fault will not cause the breaker to trip if fault current does not meet or exceed 500% of the breakers continuous current rating.
That being said there are numerous accounts of these devices functioning in a manner that saves lives and mitigates damage that otherwise would have been caused by glowing contacts etc.
I think they do work I just don't care for the manufactures pitch.
just a thought
charlie
The fact of the matter remains. The term arc fault is mis-leading in so much the these units are looking at a combination of circuit parameter.
as Don mentioned
Arcing arc signature
75 amp fault current
concurrent 30-50 mA fault to ground.
in fact a series arcing fault on a system that can not establish a ground fault will not cause the breaker to trip if fault current does not meet or exceed 500% of the breakers continuous current rating.
That being said there are numerous accounts of these devices functioning in a manner that saves lives and mitigates damage that otherwise would have been caused by glowing contacts etc.
I think they do work I just don't care for the manufactures pitch.
just a thought
charlie
charlie
Senior Member
- Location
- Indianapolis
Re: AFCI BREAKER
Charlie, they do work but they do not do what the manufacturers said they would do when they were first presented to the code making panels.</font>
Charlie, they do work but they do not do what the manufacturers said they would do when they were first presented to the code making panels.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">We were told that they would protect the building wiring system, they do.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">We were told they would protect against series and parallel arcing, they protect against only parallel arcing where the arcing exceeds 75 amperes.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">We were told they would protect cords, they don't.</font>
physis
Senior Member
Re: AFCI BREAKER
Wow, all I can think is why target the consumer when we have the CMP,s.
I mean no disrespect towards you Charlie. But I know these devices will not be made to work as promised and yet we will all continue to be forced to buy them.
I think there should be some form of sanction.
Wow, all I can think is why target the consumer when we have the CMP,s.
I mean no disrespect towards you Charlie. But I know these devices will not be made to work as promised and yet we will all continue to be forced to buy them.
I think there should be some form of sanction.
Re: AFCI BREAKER
Charlie and Physis.
I do see merit to these units and of course advocate there use. It's the Code!
I get a little aggravated constantly being in a position defending items that are not quite what they profess to be.
that being said statistically these things give up nothing that I am aware of when compared to the operation of a conventional branch circuit breaker.
They actually provide additional features AFCI and GFP.
The new Combination Devices are supposed to provide additional coverage out to zone 3 (beyond the face of the outlet). and their trip threshold is supposed to 2-5 Amps rather than 75A. They will be more sensitive.
Time will tell 3 years will be here before you know it!!
Charlie
Charlie and Physis.
I do see merit to these units and of course advocate there use. It's the Code!
I get a little aggravated constantly being in a position defending items that are not quite what they profess to be.
that being said statistically these things give up nothing that I am aware of when compared to the operation of a conventional branch circuit breaker.
They actually provide additional features AFCI and GFP.
The new Combination Devices are supposed to provide additional coverage out to zone 3 (beyond the face of the outlet). and their trip threshold is supposed to 2-5 Amps rather than 75A. They will be more sensitive.
Time will tell 3 years will be here before you know it!!
Charlie
harley
Member
- Location
- Pennsylvania
Re: AFCI BREAKER
The AFCI does protect 2 wire cords. The 75 amps is an RMS 16.6 millisec available short circuit value. The ARC signature @ the 75 amp level is less. First the arc is less than 2 millisec wide and the PEAK current can be about 50 amps. The arc may occur once every other cycle(s)positive, negative, or once every 5 cycles. The present AFCI does not directly protect loose connections but relies on degradation of insulation which becomes a phase fault or ground fault. The 30 ma. portion of AFCI is a very important component for this guarantees the installer and inspector correct wiring especially when pertaining to sub-panels. Example: A branch circuit has a grounded neutral. All currents do not return to neutral conductor to main disconnect but some leakage current finds parallel path to ground via grounded neutral thus over load neutral. AFCI will trip thermal mag will not.
The AFCI does protect 2 wire cords. The 75 amps is an RMS 16.6 millisec available short circuit value. The ARC signature @ the 75 amp level is less. First the arc is less than 2 millisec wide and the PEAK current can be about 50 amps. The arc may occur once every other cycle(s)positive, negative, or once every 5 cycles. The present AFCI does not directly protect loose connections but relies on degradation of insulation which becomes a phase fault or ground fault. The 30 ma. portion of AFCI is a very important component for this guarantees the installer and inspector correct wiring especially when pertaining to sub-panels. Example: A branch circuit has a grounded neutral. All currents do not return to neutral conductor to main disconnect but some leakage current finds parallel path to ground via grounded neutral thus over load neutral. AFCI will trip thermal mag will not.
Re: AFCI BREAKER
wait until the whole panel is filled with the afci breakers and the overheating forces retroactive derating of the panel. I agree with both Charlie and Physis, who needs advertising when the CMP buys the stuff. (the stuff being the bxxx sxxx).
I actually think that this is a fundamental shift in policy for the insurance driven industry. AFCI breakers save houses, not lives. It is not possible to come up with statistics that clearly show any lives saved. The demographic info is not there. The base would have to be fires started in bedrooms of new construction homes from faults that the afci would protect against, and the info is not seperated that way. Smoke detectors have saved so many lives that afci protection would hardly dent the statistics.
BUT it is obvious from their operation that afci's would help prevent home fires. As the cost goes up, the force is to protect the building. This is a fundamental shift in policy. To prove that this is not about saving lives, there is no provision for medically essential equipment, including phones and phone callers. Letting that non critical fault shut everything down including home medical equipment, just to protect the house, is putting the house ahead of the life safety of the occupants.
The refusal to allow emt or similar protected circuits, (from previous discussions of afci devices) the increase in home medical care, the aging of the population... maybe this is really about getting granny gone sooner.
paul
wait until the whole panel is filled with the afci breakers and the overheating forces retroactive derating of the panel. I agree with both Charlie and Physis, who needs advertising when the CMP buys the stuff. (the stuff being the bxxx sxxx).
I actually think that this is a fundamental shift in policy for the insurance driven industry. AFCI breakers save houses, not lives. It is not possible to come up with statistics that clearly show any lives saved. The demographic info is not there. The base would have to be fires started in bedrooms of new construction homes from faults that the afci would protect against, and the info is not seperated that way. Smoke detectors have saved so many lives that afci protection would hardly dent the statistics.
BUT it is obvious from their operation that afci's would help prevent home fires. As the cost goes up, the force is to protect the building. This is a fundamental shift in policy. To prove that this is not about saving lives, there is no provision for medically essential equipment, including phones and phone callers. Letting that non critical fault shut everything down including home medical equipment, just to protect the house, is putting the house ahead of the life safety of the occupants.
The refusal to allow emt or similar protected circuits, (from previous discussions of afci devices) the increase in home medical care, the aging of the population... maybe this is really about getting granny gone sooner.
paul
physis
Senior Member
Re: AFCI BREAKER
Cpal,
You really don't need to defend the idea of AFI's. It's a fine idea.
But beta versions being forced on the entire population I think is a seperate issue.
I think currently their use maybe should be voluntary. I would actually recommend them.
These things still need work and, with their use being manditory, where's the incentive to improve them?
Cpal,
You really don't need to defend the idea of AFI's. It's a fine idea.
But beta versions being forced on the entire population I think is a seperate issue.
I think currently their use maybe should be voluntary. I would actually recommend them.
These things still need work and, with their use being manditory, where's the incentive to improve them?
- Location
- Illinois
- Occupation
- retired electrician
Re: AFCI BREAKER
I still wonder how much good AFCIs can really do even if they do everything that the manufacturers claim that they do. I say this because 85% of the dwelling unit fires that were said to be of electrical origin occurred in dwelling units over 20 years old. How many of the AFCIs that we install now will be still functional as an AFCI device in 20 years. Remember that these devices are not fail safe and that the homeowner is not likely to be testing them every month as required by the instructions.
Don
I still wonder how much good AFCIs can really do even if they do everything that the manufacturers claim that they do. I say this because 85% of the dwelling unit fires that were said to be of electrical origin occurred in dwelling units over 20 years old. How many of the AFCIs that we install now will be still functional as an AFCI device in 20 years. Remember that these devices are not fail safe and that the homeowner is not likely to be testing them every month as required by the instructions.
Don
charlie
Senior Member
- Location
- Indianapolis
Re: AFCI BREAKER
I am sorry for being so cynical but I don't happen to believe the Code should be used to sell a new product. My belief is that the new product should prove itself and then requirements would be written for it.
The combination type AFCI will, I believe, do what we were told the first batch would do. If proven and the bugs are worked out, I believe they should be used for all 15 and 20 ampere circuits in dwellings. I also believe the distance in the exception to 210.12(B) in the 2005 Code should be unlimited to the first receptacle.
I am sorry for being so cynical but I don't happen to believe the Code should be used to sell a new product. My belief is that the new product should prove itself and then requirements would be written for it.
The combination type AFCI will, I believe, do what we were told the first batch would do. If proven and the bugs are worked out, I believe they should be used for all 15 and 20 ampere circuits in dwellings. I also believe the distance in the exception to 210.12(B) in the 2005 Code should be unlimited to the first receptacle.
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