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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.   

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  • In those US statistics, there seems to be a significant dollar loss for fires due to “electrical malfunction,” whatever that is. That would imply such fires have a big impact on property damage. 
    The “shall” bit of 421.1.7, on the other hand, would seem to be focused at life safety. That focus might get more traction in the post Grenfell era rather than trying to argue a case for the benefits to be had from AFDDs in mitigating property damage, especially from a set of statistics that isn’t sufficiently granular to support any such claim.

    I would hate to think that there is commercial influence behind any regulations in BS7671, whether true or not, that is the perception of many contractors when it comes to AFDDs. It is a pity because I want BS7671 to be held in the highest esteem by all in our industry.

    The OP asked do they work, I really have no idea but not only do we have to comply with the “shall” bit of 421.1.7, we also have to take the “should” bit very seriously indeed, I certainly do!

  • That would imply such fires have a big impact on property damage. 

    Might be true, because of construction materials in US (wood used far more I understand).

    The “shall” bit of 421.1.7, on the other hand, would seem to be focused at life safety. That focus might get more traction in the post Grenfell era rather than trying to argue a case for the benefits to be had from AFDDs in mitigating property damage, especially from a set of statistics that isn’t sufficiently granular to support any such claim.

    Certainly, all of the cases where AFDDs are now required appear to share common characteristics of:

    • numbers of people in the building
    • people sleep in the building
    • there may be vulnerable people in the building
    I would hate to think that there is commercial influence behind any regulations in BS7671, whether true or not, that is the perception of many contractors when it comes to AFDDs. It is a pity because I want BS7671 to be held in the highest esteem by all in our industry.

    Agreed.

  • Overall trends in the leading fire causes for the 10-year period of 2009 to 2018 show the following: ĵ Cooking as the leading cause of residential building fires for the 10-year period. ĵ An 18% increase in residential cooking fires. (This is likely due to an NFIRS coding edit implemented in 2012.) ĵ A 30% decrease in residential heating fires. ĵ A 17% increase in residential other unintentionally or carelessly set fires. ĵ A 2% decrease in residential electrical malfunction fires

    So cooking can be very dangerous.

    Z.

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  • Overall trends in the leading fire causes for the 10-year period of 2009 to 2018 show the following: ĵ Cooking as the leading cause of residential building fires for the 10-year period. ĵ An 18% increase in residential cooking fires. (This is likely due to an NFIRS coding edit implemented in 2012.) ĵ A 30% decrease in residential heating fires. ĵ A 17% increase in residential other unintentionally or carelessly set fires. ĵ A 2% decrease in residential electrical malfunction fires

    So cooking can be very dangerous.

    Z.

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