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.
I have not read or looked at what you attached - sorry I am pre-occupied with two projects at the moment.
I have not thought (yet) too much on AFDs and take your point about the UK system with magnetic/thermal mcbs, RCDs and care about wiring and earth fault impedances being successful in some/most situations of detecting parallel arc faults ie between live conductors or between line and earth and neutral and earth. I too am dubious about their efficacy in the UK setting and great potential for nuisance tripping undermining their merit.
I asked earlier 'why now' had AFDs been introduced into our wiring regulations by the IET. I don't know the answer (yet) but assumed it was to deal perhaps with serial arc faults as might be found at loose wiring connections which mcbs and RCDS usually will not detect. But then too there is the great potential for nuisance tripping of AFDs installed to detect serial arc faults as switches are opened and closed. I doubt the current state of AFD technology can distinguish reliably between true serial arc faults of wiring and normal switch operation.
I don't know enough to state a professional opinion on AFDs but do think Cookie is being genuine about how poorly AFDs perform in practice in the USA.
PS: It adds to the interest of a poster if we at least know where they hail from
though no need to give one's actual address. Recently, I quite liked to know the EF was helping a chap in Addis Ababa.
I have not thought (yet) too much on AFDs and take your point about the UK system with magnetic/thermal mcbs, RCDs and care about wiring and earth fault impedances being successful in some/most situations of detecting parallel arc faults ie between live conductors or between line and earth and neutral and earth. I too am dubious about their efficacy in the UK setting and great potential for nuisance tripping undermining their merit.
I asked earlier 'why now' had AFDs been introduced into our wiring regulations by the IET. I don't know the answer (yet) but assumed it was to deal perhaps with serial arc faults as might be found at loose wiring connections which mcbs and RCDS usually will not detect. But then too there is the great potential for nuisance tripping of AFDs installed to detect serial arc faults as switches are opened and closed. I doubt the current state of AFD technology can distinguish reliably between true serial arc faults of wiring and normal switch operation.
I don't know enough to state a professional opinion on AFDs but do think Cookie is being genuine about how poorly AFDs perform in practice in the USA.
PS: It adds to the interest of a poster if we at least know where they hail from
though no need to give one's actual address. Recently, I quite liked to know the EF was helping a chap in Addis Ababa.
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The plan is to make AFDDs global. The IEC now recommends them thanks to UL being so heavily involved with the IEC and its committees.
I'll find the link, but they also have members from Eaton on those committees. The bias is to obvious.
Truth is they can't. This is the norm in US forums:
Article 700 Emergency power components
Starting with a 700.2 compliant Emergency Power System, also known as Life Safety, with a generator meeting NFPA 110 and an ATS listed under UL1008. Customer wants to add a portable generator docking station with quick-connect plugs (aka CamLok plugs) and a manual transfer switch, also UL1008...
forums.mikeholt.com
But even if they could reliably detect serial arcs (and even glowing connections) mandating them is wrong because code should not dictate technology. Point of use thermal detection can detect serial arcing at fittings and with a much high degree of accuracy in theory. Think Thermarestor as an example. If flex was screened that would detect a series break by tripping the RCD.
The US is rather eye opening, it will tell you everything you need to know.
Feeling your pain ,
formerly whole houses on dual 30mA RCDs
with similar waking up "in the dark" experiences.
In the name of safety !
If one world government is a "fable", then why are all these prominent people talking about the creation of a one world government?
Likewise, coincidence theories abound, and coincidence theorists are ever ready to deny motive where motive may have existed.
D
Deleted member 26818
Perhaps I’m cynical?
The 18th edition now has a number of requirements or advisories which appear to have nothing to do with safety, but are more to do with increasing profits for manufacturers.
We can now no longer use anything other than a Type tested DB in domestic installations.
That means we cannot use items of equipment from different manufacturers, even if all of the items of equipment have a greater breaking capacity than the measured PFC.
We now have to follow Manufacturers’ Instructions in respect of DBs.
This means we have to install items of equipment rated at what the manufacturer’s require, rather than rated according to the expected load.
BS7671 now no longer lists RCD sockets or RCD FCUs as being acceptable for additional protection.
This means many installations will require a new DB be installed just to provide RCD protection for an extra socket.
BS7671 now requires circuits supplying luminaires be provided with RCD protection.
So again a new DB when installing an extra light.
We are now advised to install SPDs to prevent damage from lightning strikes.
This is despite the fact that damage to consumer installations from lightning strikes is very rare and occurs much less often than damage caused by loss of supply neutral.
Is it a case of safeguarding the DNOs against compensation claims, rather than protecting customer’s equipment against lightning damage?
As for AFDDs, my understanding, is that they are very unreliable and won’t work with RFCs.
The 18th edition now has a number of requirements or advisories which appear to have nothing to do with safety, but are more to do with increasing profits for manufacturers.
We can now no longer use anything other than a Type tested DB in domestic installations.
That means we cannot use items of equipment from different manufacturers, even if all of the items of equipment have a greater breaking capacity than the measured PFC.
We now have to follow Manufacturers’ Instructions in respect of DBs.
This means we have to install items of equipment rated at what the manufacturer’s require, rather than rated according to the expected load.
BS7671 now no longer lists RCD sockets or RCD FCUs as being acceptable for additional protection.
This means many installations will require a new DB be installed just to provide RCD protection for an extra socket.
BS7671 now requires circuits supplying luminaires be provided with RCD protection.
So again a new DB when installing an extra light.
We are now advised to install SPDs to prevent damage from lightning strikes.
This is despite the fact that damage to consumer installations from lightning strikes is very rare and occurs much less often than damage caused by loss of supply neutral.
Is it a case of safeguarding the DNOs against compensation claims, rather than protecting customer’s equipment against lightning damage?
As for AFDDs, my understanding, is that they are very unreliable and won’t work with RFCs.
It will only get worse unless people put a stop to it. They count on your silence and compliance as consent. US electricians are starting to see the light. Another case in point:
The GFCI requirements are coming from people getting killed on none compliant installations. So how will mandating more GFCIs solve the issue of people refusing to follow the code in the first place? And speaking of that handy work is getting worse because home owners don't understand why an electrician costs 5x as much with call backs vs a handy men that won't cause $500 worth of groceries to go bad when the fridge AFCI trips.
Equipment Grounding question
All, Please see picture attached. Is this the correct size grounding conductor required for equipment grounding? 2 of the power panels have 100A main breaker and the other 2 have 150A main breaker. The transformers are 25KVA. The Fiber panel is a Corning ICH-12P, Nema 3S, I believe. A #4 seems...
forums.mikeholt.com
The GFCI requirements are coming from people getting killed on none compliant installations. So how will mandating more GFCIs solve the issue of people refusing to follow the code in the first place? And speaking of that handy work is getting worse because home owners don't understand why an electrician costs 5x as much with call backs vs a handy men that won't cause $500 worth of groceries to go bad when the fridge AFCI trips.
Have a look at the John Ward videos on youtube when he tested one.
Yup, saw them. And a perfect example of why they don't work. Most appliances draw less then 5 amps and most circuits are loaded below that as well. Joule heating can take place under 1 amp. So right here we do not have any fire protection, and above 5 amps its hit or miss... because it may just be an appliance doing its normal thing.
Which brings me to the arc detection logic itself. You need the computing power of at least an Iphone to get reliable discrimination. And even then the AFDD must be programmed to take into account thousands of benign waveforms "learning" what is ok and what isn't. The whole concept even with the right intentions is impractical. Maybe as computing power increases and cost decreases but till then- no.
If anyone doesn't know what Joule heating is here is a description
joule heating - Bing
Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.
(That one put me to sleep.)If anyone doesn't know what Joule heating is here is a description
joule heating - Bing
Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.www.bing.com
100% Efficient conversion of electrical energy to heat,
in a region of high relative Resistance ,
I squared R Losses . (or am I wrong)
Very interesting thread. And no doubt there are hundreds of firefighters throughout the country breathing a sigh of relief now that they know these things don't work.
They were all thinking they would have to start doing a proper fire investigation instead of the old standby, cause of fire, "electrical".
They were all thinking they would have to start doing a proper fire investigation instead of the old standby, cause of fire, "electrical".
In the US most fires are written off as "electrical". Unless arson is suspected the fire is not thoroughly investigated. And even then its hard to find a cause when all you have is a pile ashes. So fire statsitcs from the states are very skewed.
Interesting fact: fire sprinklers are actually mandated in US homes but its amended out at the local level 99.99% of the time.
The Brits have long complained that many Americans don't get irony (for instance, we published a telling story from a British expat last week, and then there was the time the editor of Business Insider UK griped on Twitter about his literal American editors).
Well, there's a reason we don't get irony, and it's not because we're daft.
the British, despite being more low-context than many cultures, are far more high-context than the Americans. Thus they will often say things with implicit meanings that are contrary to their literal meanings — aka irony — that go right over American heads.
www.businessinsider.com
Nothing personal, it's just me. I'm retarded, and am only here for the humour
Well, there's a reason we don't get irony, and it's not because we're daft.
the British, despite being more low-context than many cultures, are far more high-context than the Americans. Thus they will often say things with implicit meanings that are contrary to their literal meanings — aka irony — that go right over American heads.
Here's The Real Reason Americans Don't Get Irony
There's a very good historical reason.
www.businessinsider.com
Nothing personal, it's just me. I'm retarded, and am only here for the humour
'Just kidding', tel?you were right the first time.
I shall treat that comment as irony.you were right the first time.
The Brits have long complained that many Americans don't get irony (for instance, we published a telling story from a British expat last week, and then there was the time the editor of Business Insider UK griped on Twitter about his literal American editors).
Well, there's a reason we don't get irony, and it's not because we're daft.
the British, despite being more low-context than many cultures, are far more high-context than the Americans. Thus they will often say things with implicit meanings that are contrary to their literal meanings — aka irony — that go right over American heads.
Here's The Real Reason Americans Don't Get Irony
There's a very good historical reason.
Nothing personal, it's just me. I'm retarded, and am only here for the humour
What did I miss?
My comments about firefighters was not supposed to be taken seriously. Then you come along and start to give my comments credibility, which would never do. So I needed to point out the irony and the fact that you "don't get it".What did I miss?
On balance I decided it was better to upset one American than the whole of the British Fire Service.
Agree, don't take much to upset the Yanks, just tell em their electrics are carp, that usually gets their dander up, invasion will follow, internment of UK Sparks accused of blasphemy etc. Drone strikes on the IET HQ, Mass burning of the BS 7671.
then fix the lack of loop impedance testing. cure the disease, not the symptoms.
There was I recalling that you reckoned RCDs and CBs detected Arc faults.
Hi cookie
Sorry for diverting your thread a little.
You have raised some interesting points, and I, for one, would be interested to know why we Have welcomed them with open arms and by who, and was the science behind it known to them. Or did they simply believe the manufactures?
But first off, it would help to know why you have taken up this cause, what your involvement is, and what your experience is to enable you to make these claims. Whilst ever you avoid these matters, then your credibility here is no better than mine. So come on, open up a bit so we know you are genuine.
Sorry for diverting your thread a little.
You have raised some interesting points, and I, for one, would be interested to know why we Have welcomed them with open arms and by who, and was the science behind it known to them. Or did they simply believe the manufactures?
But first off, it would help to know why you have taken up this cause, what your involvement is, and what your experience is to enable you to make these claims. Whilst ever you avoid these matters, then your credibility here is no better than mine. So come on, open up a bit so we know you are genuine.
D
Deleted member 26818
On the one hand, you say the poster has raised interesting points, on the other, you want to know more about the poster before you assign any credibility to the interesting points?
T
The Ghost
Having thought about this I don't buy the idea that RCDs' can act as AFD devices. Thinking of the construction of an RCD it is a toroidal coil set up to sense an imbalance between L-N so the sum in will equal the sum out to simplify it. Arcing between L-N or L-L would not be picked up by an RCD from what I understand. The evidence presented by the OP has too many variables in it to conclusively agree with the findings presented. In effect he is saying that the introduction of AFCI devices is the fraud on top of GFCI already existent? An arc is surely a fault/short of negligible impedance which will cause thermal and em effects which is catered for by an common or garden MCB. And then the RCD comes in as a distinctly different function i.e. as "additional protection" the fact it may trip in an arc situation I believe is accidental/incidental and would not be relied on as arc detection and may even be dangerous to do so.
B
Bobster
I agree.
RCDs, and MCBs do not operate in the same manner as an AFDD. Their sensing mechanisms are different. Yes both an MCB and RCD can detect an arc (If the magnitude is big enough/ it is from L>E).
Partially correct that they are introduced in the US due to loop impedance. However, and i guess this is hand in hand with EFLI. In the US portable appliances are not protected like the ones in the UK, they don't generally have fused outlets/plugs. As such the appliance wiring normally isn't enough to deal with the fault current necessary to trip the thermal strip in an MCB. Hence, fire.
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