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AFDDs - when do they work?

alanblaby

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
  • 0

    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.

  • 0 in reply to AJJewsbury

    I wonder if the flashing sequence for 'arcs' is triggered under the 'Don't know' category'?

  • 0 in reply to whjohnson

    The biggest objection to fitting this new expensive stuff is the cost. The new stuff has virtually all arrived together. S.P.Ds, A.F.D.Ds, new types of R.C.D. that advertise that they are resistant to D.C. "blinding". The consumer just can't be expected to pay for stuff that they do not understand and can't possibly afford.

    Z.

  • 0 in reply to AJJewsbury

    "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.

  • 0 in reply to Zoomup
    Zoomup said:
    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.

    Zoomup said:
    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."

Reply
  • 0 in reply to Zoomup
    Zoomup said:
    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.

    Zoomup said:
    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."

Children
  • 0 in reply to gkenyon

    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.

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