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The Arc Fault Detection Device… again.

whjohnson
Some humourous but valid observations on AFDDs, the state of the industry, the wiring regs and future amendment requirements.

He also attempts to build a AFFD tester which electrically tests rather than relying upon the mechanical action of the test button on the device itself.

https://www.youtube.com/watch?v=e0ElFaKc_e8

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  • 0
    Farmboy:



    The presenter in this video claims that in the US, AFDDs have reduced numbers of domestic fires by nearly 20% - good enough reason to install them, is it not?


    There were 3,862 fires due to faulty appliances and leads in 2019/20 (Government fire statistics). It isn't clear by any means how many were started by an arc, let alone a detectable one, but let's assume for the moment that all of them were.


    The average area of damage was 16.5 m² i.e. the size of a fairly ordinary sitting room. I haven't found official statistics, but Plumis who make sprinkler systems say the average cost is £25k, which seems reasonable. For comparison, new build costs are around £2,000/m².


    There is no indication whether fires caused by faulty appliances and leads are bigger or smaller than average. So 3,862 fires @ £25k = just under £100M per year.


    There are 24.4 million dwellings in England (Government dwelling stock statistics) so the cost near as makes no difference is £4 per dwelling.


    If an average AFDD lasts 20 years, then a whole CU-full needs to cost less than £80.


    I conclude that at the moment, AFDDs are not cost-effective.


    Now then, would nobody care to discuss the cost-benefit ratio of fire alarm systems? ?


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  • 0
    Farmboy:



    The presenter in this video claims that in the US, AFDDs have reduced numbers of domestic fires by nearly 20% - good enough reason to install them, is it not?


    There were 3,862 fires due to faulty appliances and leads in 2019/20 (Government fire statistics). It isn't clear by any means how many were started by an arc, let alone a detectable one, but let's assume for the moment that all of them were.


    The average area of damage was 16.5 m² i.e. the size of a fairly ordinary sitting room. I haven't found official statistics, but Plumis who make sprinkler systems say the average cost is £25k, which seems reasonable. For comparison, new build costs are around £2,000/m².


    There is no indication whether fires caused by faulty appliances and leads are bigger or smaller than average. So 3,862 fires @ £25k = just under £100M per year.


    There are 24.4 million dwellings in England (Government dwelling stock statistics) so the cost near as makes no difference is £4 per dwelling.


    If an average AFDD lasts 20 years, then a whole CU-full needs to cost less than £80.


    I conclude that at the moment, AFDDs are not cost-effective.


    Now then, would nobody care to discuss the cost-benefit ratio of fire alarm systems? ?


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