Filthy Phil
Member
I asked my apprenticeship instructor if a groung fault rec. will work on a circuit that is arc fault protected. He told me to figure it out. Any ideas?
Ground fault on an arc fault circuit
- Thread starter Filthy Phil
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yeah, go figure it out. :grin: You will find if you hook it up it will work just fine. I have done it on numerous occassions.
Does your instructor know the answer or did he want you to hook one up and see what happens? I saved you the trouble. I'll send the bill. :grin:
Does your instructor know the answer or did he want you to hook one up and see what happens? I saved you the trouble. I'll send the bill. :grin:
Filthy Phil
Member
Thanks. He isn't a very good teacher. He usually just yells, and if you don't understand, he just yells louder.
macmikeman
Senior Member
- Location
- Planet macmikeman
Filthy Phil said:
Well Filthy Phil, maybe if you just spruced up a bit before coming to class he might not be so uptight...:grin: (just joking, please don't become "angered at macmikeman" Phil)
AES1005
Member
- Location
- Nitro West Virginia
Tripping Current
Tripping Current
From what I understand the only difference in an "arc Fault vs Ground Fault is the the amount of current required to trip the device. GF=400ma AC=200/600 ma?
Tripping Current
From what I understand the only difference in an "arc Fault vs Ground Fault is the the amount of current required to trip the device. GF=400ma AC=200/600 ma?
rcarroll
Senior Member
- Location
- Fort Collins, Colorado
Are you paying this teacher to yell at you?Filthy Phil said:
Bob Kraemer
Senior Member
- Location
- Ohio
This doesn't have anything to do with your question, but if your instructor is not very good and just yells, file a complaint with the apprenticeship board.
weressl
Esteemed Member
Filthy Phil said:
Ground fault protection is looking for the sum of current to be nearly 0. It monitors the "Hot" and the "Neutral" and if there is a difference then the current is returning though another path, the ground fault. Since the wire capacitively couples to the earth there is always a small leakage current due to that that does not return via the "neutral" and allowance must be made for that. NIOSH says that 16mA is the maximum a human can hold and let go. So the GF protective devces are set at a lower level. There are other GF protective devices where it is to protect circuits that are expected to have a higher than normal leakage current, such as heat tracing circuits. Those have a higher trip current, I believe 30mA.
Arc Fault monitoring can be done by measuring the MAGNITUDE of the current. Since the primary objective is to prevent fires the monitoring is watching for evidence of excessive heat generated. Arcing faults occur when a connection loosens. The mechanics are lenglthy to explain, so it is sufficient to say that it occures over time. It manifest itself in spiking currents and measuring those currents AND the duration and integrating the two into an I^2*t formula will be an indication of heat. One of the difficulties is to differentialte this from your 3 year old who loves to stand at the lightswitch and flicking it on/off several hundred times. (Doesn't everyone has one, especially those of us in the electrical trade?) This type of fault monitoring reaches below the range of the thermal limits of plain overload protection as arcing faults would not necessarily reach the "thermal mass" needed to reach into the overload protective range.
So in short, the two can coexist without interfering with each others task.
- Location
- Illinois
- Occupation
- retired electrician
According to the AFCI people that is not the type of arc fault that the AFCI looks for. That is a series arcing fault and the AFCIs only directly detect parallel arcing faults. They detect poor connections or series arcing faults when the heat from the fault causes enough damage so that the fault becomes a ground fault or a parallel arcing fault.
Don
Energize
Senior Member
- Location
- Milky Way Galaxy
don_resqcapt19 said:
Jan 1st the AFCI requirement changes to include combination arc fault that includes series arching.
If I knew how to post a picture I have a pretty good example.
weressl
Esteemed Member
don_resqcapt19 said:
Could you please let them supply you with the detailed technical explanation of how do they accomplish this and post it here. It would be also helpfull if they can furnish you with the historical origin of the problem that generated the development of this device.
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
Adults that yell need to grow up, teachers that yell need to QUIT.
- Location
- Illinois
- Occupation
- retired electrician
Laszlo,
Don
They do not release that type of information.
This device was strongly pushed by the CPSC, and of course the manufacturers.
Don
- Location
- Illinois
- Occupation
- retired electrician
I am not convinced that is the case, especially since the AFCI people went to great lengths a few years ago to say that a series arc is not even possible at dwelling unit voltages.
Don
weressl
Esteemed Member
Don,
Help!
What is CPSC?
I'll see if I can find the information on what GFCP does and how it works. I have talked to some of the fols that actually worked on the development and there was nothing secretive about the method. Now how they built the circuit is another question.
Help!
What is CPSC?
I'll see if I can find the information on what GFCP does and how it works. I have talked to some of the fols that actually worked on the development and there was nothing secretive about the method. Now how they built the circuit is another question.
Energize
Senior Member
- Location
- Milky Way Galaxy
don_resqcapt19 said:
You may not be convinced, but 210.12 (B) is very clear and very specific.
Energize
Senior Member
- Location
- Milky Way Galaxy
- Location
- Illinois
- Occupation
- retired electrician
Energize,
I really don't care what the manufacturers say about AFCIs...they have lied from day one on this issue. Their original proposals some 13 years ago said that the device they had back then would do everything that the combination type is said to do and the combination type is just getting to the market now.
Edit...My comment is a bit harsh, but the AFCI people provided a lot of technical information in the years before they had a combination type AFCI that said a series arc at dwelling unit voltages was not possible. They did say that a poor connection could make enough heat to cause a fire external to the outlet box, but they also said that it is likely that the fault would become a parllel arcing fault or a ground fault and the AFCI would trip before a fire started.
I am not convinced that the AFCI rule is cost effective....the costs far outweigh the benefits. Yes they will prevent some fires, injuries and even deaths, but there has to be a line drawn somewhere as to the cost of safety. If the cost of safety was not important, the only wiring method that would be permitted is rigid steel conduit as it is safer than the other wiring methods, but that too, would not be cost effective. If the cost of safety was not important, we would all be driving tank like vehicles, without the gun, as that would reduce traffic deaths, but again, not a cost effective solution. In the first year of full compliance with the 2008 AFCI rule, the AFCIs could prevent about 435 fires if they could pervent every fire that is said to be of electrical origin. The total cost of compliance to prevent these fires will be about 658 million dollars or 1.5 million dollars per fire prevented.
I really don't care what the manufacturers say about AFCIs...they have lied from day one on this issue. Their original proposals some 13 years ago said that the device they had back then would do everything that the combination type is said to do and the combination type is just getting to the market now.
Edit...My comment is a bit harsh, but the AFCI people provided a lot of technical information in the years before they had a combination type AFCI that said a series arc at dwelling unit voltages was not possible. They did say that a poor connection could make enough heat to cause a fire external to the outlet box, but they also said that it is likely that the fault would become a parllel arcing fault or a ground fault and the AFCI would trip before a fire started.
I am not convinced that the AFCI rule is cost effective....the costs far outweigh the benefits. Yes they will prevent some fires, injuries and even deaths, but there has to be a line drawn somewhere as to the cost of safety. If the cost of safety was not important, the only wiring method that would be permitted is rigid steel conduit as it is safer than the other wiring methods, but that too, would not be cost effective. If the cost of safety was not important, we would all be driving tank like vehicles, without the gun, as that would reduce traffic deaths, but again, not a cost effective solution. In the first year of full compliance with the 2008 AFCI rule, the AFCIs could prevent about 435 fires if they could pervent every fire that is said to be of electrical origin. The total cost of compliance to prevent these fires will be about 658 million dollars or 1.5 million dollars per fire prevented.
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- Location
- Illinois
- Occupation
- retired electrician
Energize
Senior Member
- Location
- Milky Way Galaxy
don_resqcapt19 said:
I really don't care either.
I posted
and you replied
All I was saying is it is in the 2005 NEC, Effective Jan1 2008, like it or not. Since you posted your comments below my NEC requirement quote, I thought you meant you were not convinced it was a NEC requirement.
[quote]I am not convinced that the AFCI rule is cost effective....quote]
Had you said that in the with my original quote, I would have understood your position concerned the cost effectiveness and not the NEC requirement and I would not have replied.
Whew! Glad that is now as clear as mud.
And we wonder why 435 members of Congress cannot pass a "simple" bill!
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