A.F.D.D. with a combined M.C.B. unit, the tripping may just be due to overcurrent, so we may not know which part of the device has caused the tripping off.

All the ones I looked at had some means of indicating the cause of the trip - usually coloured/flashing LED - different flashes for Arcs, RCD or overcurrent - so probably better than many an RCBO.

  - Andy.

So, an A.F.D.D. trips off due to a fault, then is reset by somebody but it won't stay on. Do the flashing lights stay on that identify the type of fault?

AND, what benefit is there in knowing the type of fault anyway by the flashing lights, as an electrician will normally and hopefully locate it by conventional means anyway. 

Z.

Zoomup said:

So, an A.F.D.D. trips off due to a fault, then is reset by somebody but it won't stay on. Do the flashing lights stay on that identify the type of fault?

AND, what benefit is there in knowing the type of fault anyway by the flashing lights, as an electrician will normally and hopefully locate it by conventional means anyway. 

Different manufacturers have different implementations, and you'd need to check specific products out, but why wouldn't the electronics inside the AFDD be able to stay on from the input, whilst the output circuit (containing the supposed fault) is disconnected?

I was wondering about the longevity of these things. How many non-arc faults - over-current/short circuit -  will they tolerate before the electronics gives up the ghost? There's a arc extinguishing chute in there somewhere which needs to snuff out heavy fault current arcs withing the device itself.  I know that certain brands of RCBO tend to die after relatively few operations under service conditions. That'll be one hell of an expensive 'fuse' to replace when it fails.

All protective devices are only specified to operate for a finite number of times (in the case of fuses themselves, 1).

Indeed. But there is a lot of variance in terms of resilience between products from different manufacturers when it comes to electro-mechanical devices, and now we intend to introduce fragile silicon chips into the mix.

I can foresee where that might lead us. whereby in the event of a fault, the 'licenced control box engineer' will be called out to diagnose and remedy the problem. He will most likely have to have a annual subscription to the company which supplied the control software in order to access the the internals with his laptop. This will be on some 'cloud' or other, with a password or PIN which changes monthly. He will have to be paid up in order to 'reset' any device which has disconnected once the fault has been diagnosed and cleared. Of course, if the CPU in the consumer unit has died, that means a very expensive job.

To me this is a nightmare scenario - there appears to be an overriding tendency to over complicate simple processes to no positive advantage.

'Cloud' means someone else's computer beyond your control, and 'software' should translate to 'nightmare', especially for early adopters.And of course, product life cycles get shorter and shorter, the ongoing provision of backups and security patches represents an expense to the manufacturer and is quickly dropped in favour of the 'Next Big Thing to be released the following year. Witness all those hacked doorbell cameras and other 'smart' devices around the home recently.

Try 'hacking' remotely into the humble 3036 fusebox and let me know how you get on.

"...and the actual death toll was reduced to about a third of that"

 none of it can be verified and proved to an agreed consensus between subject competent folks and the ones who are questioning what's gone on and the claims of effectiveness and success etc are maligned, ridiculed and suppressed ...  :-)

whjohnson said:

and now we intend to introduce fragile silicon chips into the mix

They are here already in other protective devices - for HV and very large LV installations ... and have been for over 25 years.

psychicwarrior said:

and the claims of effectiveness and success etc are maligned, ridiculed and suppressed ...  :-)

Isn't that where this thread started, in respect of AFDDs, though?

I agree, in the grand scheme of things, it's really difficult, and, as I pointed out with the discussion on vehicle safety equipment, there are definitely 'different realities' depending on your own point(s) of view, various 'vested interests' (even if it's only a desire, or encouragement, to not comply with the standard or legislation), the validity we each ascribe to assumptions and statistics, etc.

If your installation has multiple arc faults, then you have bigger things to worry about than how long your AFDD is going to last.

If your installation has multiple arc faults, then you have bigger things to worry about than how long your AFDD is going to last.

Please expand on that comment.

Z.

The threading on this topic has got terribly confused, so my last post doesn't make sense without context.  It was a response to an earlier post by whjohnson:

I was wondering about the longevity of these things. How many non-arc faults - over-current/short circuit -  will they tolerate before the electronics gives up the ghost?

To which my response was that if you have so many arc faults in your installation that the AFDDs start failing, then the AFDDs failing is the least of your problems.  You need to fix all those faults before the entire installation burns down.

Thankyou all for the replies.

In summary, they meet a product standard, but we do not know how that product standard works in real life situations, or even if it will work at all.

The Manufacturers should be shouting from the rooftops how these devices save lives and properties through their advanced designs, yet we have silence. If they are so good, why aren't they promoting their designs?

It seems there are no peer reviewed papers showing that they save lives/property, but some reports that fire figures may be slightly down, from the USA.

I've got to ask, how did the JPEL committee approve their use without factual evidence?

If they have evidence, maybe it could be published?

If there was some credible evidence that they work, then it would be an easy sell, but how can one recommend, or mandate them with such poor information available to the Installers? 

Maybe it is time for the JPEL Committee to get the Manufacturers to release their testing data to show they work, then we wouldn't be so cynical if it showed they do work, and we could sell them with no doubts as to their life saving capabilites.

In the meantime, I still don't know if, and when, they would work, and have to sell these to Customers, and say they are for their own good, but cannot back up that statement.

"I've got to ask, how did the JPEL committee approve their use without factual evidence?"

Alan,

I have been trying to ask this question so many times in so many ways but all I get is along the lines of 'No need for you to know that. Trust us, we know what we are doing", which makes me even more suspicious about these things than I already was.

All we seem to get is a swerve back to 'It's just like RCDs were back in the day'.

I say, RCDs are pretty simply devices which use easily understood physics and passive components.

AFDDs on the other hand have a computer driven by algorithms for which they rely upon to recognise the fault and operate accordingly.  These algorithms are pretty much beyond the comprehension of the average bear and are pretty much a black art to the humble sparky. This leaves a serious credibility and trust issue when it comes to adoption and acceptance of something new which might work but not in every instance, or even when it should.

My summary is that I shall not be recommending them in any future instance until they have a proven track record for doing what they say they do on the tin, regardless of JPLE/BS7671 et al.

I couldn't agree more.

Note that the manufacturers are part of jpel

Indeed.

BEAMA GAMBEICA JPLE BS7671.

It leaves a certain whiff in the air doesn't it.

As Smutts said to Churchill during a WW2 meeting on the existence or not of German Radar. "The evidence may not be conclusive, but a jury would convict.'.

Follow the money.......

whjohnson said:

BEAMA GAMBEICA JPLE BS7671.

It leaves a certain whiff in the air doesn't it.

I'm astonished at that conclusion. The front of BS 7671 (page 13 of the brown book) lists the representatives and the organisations they represent. The numbers don't look skewed?

It's not solely down to the number of parties representing each 'side' Graham, it's the amount of clout, financial or otherwise that each one brings to the table. You might have an equal number of giants on one side of the table and an equal number of dwarfs on the other, but guess who wins when it comes to doing the heavy lifting and the decision in which to travel on any issue is made.

Edited for clarity - I hope.

whjohnson said:

It's not solely down to the the number of parties representing each 'side Graham, it's the amount of clout, financial or  otherwise that each one brings to the table.

I'm not quite sure what you are saying here?

whjohnson said:

You might have an equal number giants on one side of the table and an equal number of dwarfs on the other

I'm intrigued ... could you expand on that?