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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
  • OK Graham, you ask for "Laboratory tests" well I am quite happy to provide complete data on my tests. Will that satisfy you that this discussion is relevant and necessary? In the meantime the USA code has mandated AFDDs in all installations, which I suggest is now about 25% of the total. Your job is to collect the fire statistics showing that this has made a statistically significant change. Your effort and mine will be similar, and will cost both of us a significant sum of money. I am ready.

Reply
  • OK Graham, you ask for "Laboratory tests" well I am quite happy to provide complete data on my tests. Will that satisfy you that this discussion is relevant and necessary? In the meantime the USA code has mandated AFDDs in all installations, which I suggest is now about 25% of the total. Your job is to collect the fire statistics showing that this has made a statistically significant change. Your effort and mine will be similar, and will cost both of us a significant sum of money. I am ready.

Children
  • Your effort and mine will be similar, and will cost both of us a significant sum of money.

    Perhaps that's why the conclusive data you're seeking isn't there yet.

    It's really interesting how this industry skips between different positions on the topic of improving safety, from "Any life saved is worth it" at one end of the scale to "prove to me beyond a shadow of a doubt that it's worth it."

  • In the meantime the USA code has mandated AFDDs in all installations, which I suggest is now about 25% of the total. Your job is to collect the fire statistics showing that this has made a statistically significant change.

    Report from US Fire Administration, page 4 of 13: https://www.usfa.fema.gov/downloads/pdf/statistics/res_bldg_fire_estimates.pdf

    The blue line 'Electrical malfunction' actually shows 34 % decrease in fire injuries with electrical cause ... which perhaps aligns with your estimate of what you'd expect to see (but I would perhaps argue older installations without AFDDs ought to skew the other way ... so does that mean they're better than you'd expected?).

    I don't think this is conclusive, though, because the electrical faults are under a single banner, and not causal.

  • Thank you Graham, that is an interesting read , and as I have the ability to replot the UK data in a similar format (adding appliance and distribution fires from from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1010164/domestic-appliance-fires-datatset-120821.ods ) when I get a bit of time I shall do so later. (as I am already doing this for someone else.)

    Meanwhile the simple one for the UK over the same period is below with the 2 groups separated. We have ~ 27 million households, although in flats etc one fire may affect more than one. According to the US census there are 122,354,219 US households, so we might expect a ratio of ~ 5:1 all being equal..  Actually that seems broadly right but the method of recording will not be quite the same . Not sure what the finer structure of the curves means without more investigation.

    There is no easy equivalent of dollar loss in the UK figures but we should be able to overlay the other trends and do a with/without comparison.