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AFDDs - when do they work?

I'm struggling to see the benefots of fitting AFDD's.

I've searched the web, but cannot find any compelling evidence that they actually help in safety.

 The Proffesional Journals all say they are a good thing, but with little content to show the data used to show they make a difference.

As we know, many fires are not caused by arcs, the build up of fluff in a tumble dryer is a typical example.

When I did my Social Housing work, I found many burnt out shower switches, along with washing machine sockets and occasional cooker switches that were totally burnt around the terminals, yet, in many cases would still work until the switch finally fell apart. Clearly some of these switches had been arcing, then had fused the cable to the terminal, others showed black terminals with only a small contact area, thus heating the terminals and causing the 'fishy' smell, which was quite typical.

Is there any evidence that AFDD's would stop these failures?

What about internal appliance faults?

Wasnt Grenfell started in a fridge? If so, would AFDD detect that fault?

And, what are appliance manufacturers doing to make their goods safer? From what I see, there are still thin tin plate terminals on cookers,and poor, loose spade terminals inside firdges and other appliances.They are made to be as cheap as possible, and it shows when you tighten up a terminal, and it bends the back plate as it is so thin.   

Parents
  • 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.

  • "Joyce, was it dot dot dash or dash dash dot for a trip by a arc fault?"

    "No John I think it was dot dot dot dash"

    "Fred's down the road is green, red, red.

    "Where's that instruction sheet that the sparks left"

    "Oh, I think that the dog ate it"

    "Lets go online"

    "We can't, the powers off and the router has crashed".

    "Oh Ek!" "And wasn't Fred's green, green, red?

    Z.

  • The biggest objection to fitting this new expensive stuff is the cost.

    Yes, that was the case with RCDs. I'm sure the cost will come down ... already started to happen.

    The consumer just can't be expected to pay for stuff that they do not understand and can't possibly afford.

    421.1.7 Arc fault detection devices (AFDD) conforming to BS EN 62606 shall be provided for single-phase AC final circuits supplying socket-outlets with a rated current not exceeding 32 A in:
    • Higher Risk Residential Buildings (HRRB)
    • Houses in Multiple Occupation (HMO)
    • Purpose-built student accommodation
    • Care homes.
    NOTE 1: Higher Risk Residential Buildings are assumed to be residential buildings over 18 m in height or in excess of six storeys, whichever is met first. It is anticipated that in many areas higher risk residential buildings will be defined in legislation which can be subject to change over time, as well as in risk management procedures adopted by fire and rescue services. Current legislation should be applied.
    For all other premises, the use of AFDDs conforming to BS EN 62606 is recommended for single-phase AC final circuits supplying socket-outlets not exceeding 32 A.

    In the highlighted part ('shall'), likely only the first bullet would be consumers as the client? In those premises, is it not pertinent to simply say it's there to help protect against fires? Just plain and simple? Any further questions in those premises, the answer could be "Introduced in the Amendment following Grenfell".

    So, no long explanations.

    Similarly, it could be offered in other premises quite easily, "There's a new device available to help stop fires. A bit expensive. Would be required if I were doing this job in a block of flats ... recommended in the Wiring Regs."

  • "Oh Ek!" "And wasn't Fred's green, green, red?

    I agree ... what's more frustrating with the situation about indications, is that there's actually a standard that could be used, BS EN 60073. Yes, it applies to industrial controls and similar uses, and not mandated for other products, but nevertheless, would provide some uniformity to the situation regarding colours of indications and use of that with flashing etc.

    Much better than "well, a blue LED looks good, let's just confuse everyone and use that. Now, how many flashes for standby?"

  • RCDs, SPDs, Fuses, MCBs etc are merely passive components. We know how they are supposed to work and can test them up to a point. They are 'dumb' and just sit there until the condition they are designed to address occurs.

    AFDDs are active devices which contain a cpu and are driven by algorithms. One might say they are semi-'smart'.

    AFDDs are a completely different ballgame to the other passive devices I have mentioned.

    We have all witnessed how good algorithms are when it comes to writing and applying them into real world problems.

    I recall a certain now-infamous Professor predicting something like half a million deaths in the UK at the beginning of the pandemic..................

    Then of course, we have algorithm-driven 'bots' which drive search engines and the like. Type certain words into a search engine and you might not get what you were looking, but something embarrassingly different!

    It wouldn't take a great leap into the unknown to predict 'smart' consumer units, which would be capable of monitoring a preloaded load profile for every appliance in your house. Couple this via some metadata to your smart meter and your supplier could look up what you have switched on at any time.

    "Flashing red light on Supplier's control room console summons the attention of the keyboard operative  - Mrs Gumby has her washer and dryer on and the windmill isn't turning - switch her off NOW!"

    Down the wire goes the 'Make It Dead' signal to the relevant 'smart' circuit breaker in Mrs Gumby's cu  and off goes her washing until the wind blows again.

    Just because we might be able to do something doesn't always mean that we should.

  • I recall a certain now-infamous Professor predicting something like half a million deaths in the UK at the beginning of the pandemic

    That was the predicted death toll for if the government took no action. So the government took lots of actions - lockdowns etc - and the actual death toll was reduced to about a third of that.

  • H.M.O.s are often privately owned. The question is WHEN do these unproven "fire preventing" devices have to be installed? In existing installations?

    Z.

  • Then when Mrs. Gumby's clothes get smelly and mouldy in the machine she has to put them on at least one or maybe two new wash cycles to remove the smells.

    Z.

  • And she can't dry them outside because it's raining and the wind isn't blowing!

    Never mind eh, Mrs Gumby is delighted to be doing her bit for the environment despite being charged a hefty premium to put up with regular supply interruptions.

  • I wonder which of his algorithms told him it was ok to visit his German mistress despite his own advice to the rest of us?

  • AFDDs are a completely different ballgame to the other passive devices I have mentioned.

    Circuit-breakers have, for some time, had intelligence in them. Granted, not the "for use by ordinary persons" breakers, but it's nothing new to me to see "computers" in protective devices.

    I think you're dead right, that there's way more mileage out of "SMART" devices to be marketed in the future.

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  • AFDDs are a completely different ballgame to the other passive devices I have mentioned.

    Circuit-breakers have, for some time, had intelligence in them. Granted, not the "for use by ordinary persons" breakers, but it's nothing new to me to see "computers" in protective devices.

    I think you're dead right, that there's way more mileage out of "SMART" devices to be marketed in the future.

Children
  • 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.