Derailed another thread with AFDDs, so I am starting this one. I will simply say that UK RCDs and MCBs provide arc fault protection as is. UL not only knows that, but extensively researched UK power systems in an effort to emulate the very same concept 40 years. One the simply fact (growing concern) that the US National Electrical Code does not prohibit a maximum earth fault loop impedance.
Discuss AFDDs are a massive fraud in the UK Electrical Forum area at ElectriciansForums.net
A propos WW1 and WW2 remarks: Way off topic but I think we need to remember which nation now provides and pays for (- the US taxpayer like Cookie) the extraordinary guarantee to NATO, especially since the other nations have and do not properly resource their armed forces and the UK does not too. Don't reply that we meet 2% minimum - George Osborne included among other things armed forces pensions to achieve that disambulation.
See:
www.independent.co.uk
See:
MoD using ‘creative accounting’ to meet Nato defence spending targets
Commons Defence Committee says including things like war pensions and intelligence-gathering was the only way the Government was able to meet its pledge to abide by 2% of GDP target announced in last year's summer Budget
www.independent.co.uk
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As a nudge - perhaps Westward10, Davesparks, Lucien Nunes, Wilko, Ruston might stir themselves and contribute.
Give it a bit longer Marconi, just not home yet from a busy day, may be
Its ok and fine in moderation which you have adhered to
Well, if I may, I think part of the reason can be seen right here.
The other part being that with billions you can convince anyone to believe anything especially when the are innocent and benevolent because its hard to imagine that someone else has ideas outside of protecting life and property.
If we were to keep it simple part of it is skewed science, part ignorance, part persuasion.
[/QUOTE]
Again, right here we see the psychology of why the world is what it is- standing out in the broad for all to see. The evidence is mostly self explanatory, on black and white, yet you look for dubiousness in me and not the documents presented.
I can and have taken up many causes over a broad spectrum. Ask me why hospitals are jerking with parallel switch-gear and I can fire up another thread. As of this moment I'm trying to find out why West 49th st substation completely shut down despite over a dozen systems in place specifically designed to prevent it. Your double bus single breaker outperforms breaker-and-a-half and ring bus despite all intention saying otherwise.
I see the truth. I see where people are being lead. Not letting others know of it would be worse in my mind- the mark of a psychopath.
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on the face of it, I agree with your comments. But you're assuming he's American and a tax payer. Or do you know something we don't?A propos WW1 and WW2 remarks: Way off topic but I think we need to remember which nation now provides and pays for (- the US taxpayer like Cookie) the extraordinary guarantee to NATO, especially since the other nations have and do not properly resource their armed forces and the UK does not too. Don't reply that we meet 2% minimum - George Osborne included among other things armed forces pensions to achieve that disambulation.
See:
MoD using ‘creative accounting’ to meet Nato defence spending targets
Commons Defence Committee says including things like war pensions and intelligence-gathering was the only way the Government was able to meet its pledge to abide by 2% of GDP target announced in last year's summer Budget
TL.DR version. AFDDs are a crap solution to a problem we don't have, use an RFC and forget about them.
In more detail..
From IEC62606-2103
"Residual Current Devices (RCDs) are recognised as efficient to reduce the risk of fire by detection of leakage current and arcing to ground as a consequence of tracking currents within an electrical installation. However, RCDs as fuses or circuit-breakers are not able to reduce the risk of electrical fire due to series or parallel arcing between live conductors.
During a series arc fault, there is no leakage to ground therefore RCDs cannot detect such a fault. Moreover, the impedance of the series arc fault reduces the load current, which will keep the current below the tripping threshold of the circuit-breaker and the fuse. In the case of a parallel arc between phase and neutral conductor, the current is only limited by the impedance of the installation. In the worst cases of sporadic arcs, the conventional circuit breakers were not designed for that purpose."
And the test procedure from IEC62606-2013..
"The insulation across both wires is to be slit 50 mm (or 2 inches) from one end to a depth to expose the conductors without severing any strands.
d) The slit in the insulation is to be wrapped with a double layer of electrical grade black PVC tape and overwrapped with a double layer of fiberglass tape.
e) The conductors are to be stripped at the end farthest from the slit approximately 12 mm (or 0,5 in) for connection to the test circuits. The cable specimen shall be then conditioned to create a carbonized conductive path across insulation between the two cable conductors:
f) The cable specimen is to be connected to a circuit providing 30 mA short circuit current and an open circuit voltage of at least 7 kV. The circuit is to be energized for approximately 10 s or until the smoking stops.
g) The cable specimen is to be connected to a circuit providing 300 mA short circuit at a voltage of at least 2 kV or sufficient to cause the current to flow. The circuit is to be energized for approximately one minute or until the smoking stops."
AFDDs are an attempt to reduce fires in timber buildings using relatively high-current radials, in North America where poor termination and/or breaks in conductors start fires. In the UK RFC's are inherently tolerant of single faults, a feature that makes them incompatible with AFDDs. Given the choice between an RFC and an AFDD it has to be the RFC, it's a cheaper and much more reliable way to reduce the risk of fire from a broken conductor.
In more detail..
From IEC62606-2103
"Residual Current Devices (RCDs) are recognised as efficient to reduce the risk of fire by detection of leakage current and arcing to ground as a consequence of tracking currents within an electrical installation. However, RCDs as fuses or circuit-breakers are not able to reduce the risk of electrical fire due to series or parallel arcing between live conductors.
During a series arc fault, there is no leakage to ground therefore RCDs cannot detect such a fault. Moreover, the impedance of the series arc fault reduces the load current, which will keep the current below the tripping threshold of the circuit-breaker and the fuse. In the case of a parallel arc between phase and neutral conductor, the current is only limited by the impedance of the installation. In the worst cases of sporadic arcs, the conventional circuit breakers were not designed for that purpose."
And the test procedure from IEC62606-2013..
"The insulation across both wires is to be slit 50 mm (or 2 inches) from one end to a depth to expose the conductors without severing any strands.
d) The slit in the insulation is to be wrapped with a double layer of electrical grade black PVC tape and overwrapped with a double layer of fiberglass tape.
e) The conductors are to be stripped at the end farthest from the slit approximately 12 mm (or 0,5 in) for connection to the test circuits. The cable specimen shall be then conditioned to create a carbonized conductive path across insulation between the two cable conductors:
f) The cable specimen is to be connected to a circuit providing 30 mA short circuit current and an open circuit voltage of at least 7 kV. The circuit is to be energized for approximately 10 s or until the smoking stops.
g) The cable specimen is to be connected to a circuit providing 300 mA short circuit at a voltage of at least 2 kV or sufficient to cause the current to flow. The circuit is to be energized for approximately one minute or until the smoking stops."
AFDDs are an attempt to reduce fires in timber buildings using relatively high-current radials, in North America where poor termination and/or breaks in conductors start fires. In the UK RFC's are inherently tolerant of single faults, a feature that makes them incompatible with AFDDs. Given the choice between an RFC and an AFDD it has to be the RFC, it's a cheaper and much more reliable way to reduce the risk of fire from a broken conductor.
Well looking at Cookie's avatar, he is an AMERICAN one of the World's Police Force, the special relationship and all that goes with it,
Yes I do and no I do not. I am disappointed he has not described his background and said where he lives. I tend to side with him on his views on the state of the art of current AFDDs.
A Troll, may be?????? only asking not accusing
You do know IEC62606 is a carbon copy of UL1699?
UL is in the IEC and so Eaton, I will find you the link.
The over voltage theory came about because they could not get in wall romex to arc unless it was carbonized by applying 8-15kv across it. Supposedly in the real world this would come from lightning strikes and multi kv surges jumping the gap in damaged insulation from over driven staples. This would eventually carbonize the path where 120 volts could arc across in high current and ignite the wood.
Here is that theory in depth:
Only two problems:
1) multi kv voltage spikes happening monthly would destroy any AFCI breaker and the home owners would notice when their electronics and MOVs become toasted regularly.
2) Never was pyrophoric carbonization ever considered or investigated as being a possible cause behind smoldering studs. Arcing was assumed immediately despite lab testing saying its not likely given just how many surges romex would have to take.
Had I known, I would have used an anonymous proxy. But that could get me banned. I've long learned international forums have a bit of an interest with what country a person resides in.
With that said I not only do not support what the US does, I DESPISE it.
But it should not matter in this conversation. Its not about politics but AFDDs. And if anything the fact they come from a country that is renowned for profit over all else should speak for itself.
If you want BS7671 to balloon to 3,500 pages and make any job cost so much muppets take over your respectable job turning the UK into a 3rd wold country of shocking knobs and hobs... great for you. But I don't think everyone would want that. Certainly not me.
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