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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.   

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    When they were first introduced in the wiring regs I did some research.

    All the statistics I could find in America assumed that all electrical fires were caused by Arc faults and I could not see a correlation between the introduction of AFDDs and a decrease in electrical fires.  This exercise was made more difficult by the individual states using different terminology and collecting different statistics. Bear in mind that America used to use a lot of aluminium cable in house wiring  and the outlets are not fused. 

    Digging deeper I found papers by an safety conscious American electrical engineer, who's name I cannot remember, who started out writing papers and having meetings with electrical distributors where he was trying to get them to install fuses at the house end of distributers cables. He was also trying to get the MCBs used in consumer units to be made more sensitive, from what I read the MCBs used at the time were similar to our D types. He then started on Arc fault detection having been involved in the examination of a number of electrical fires and I believe had a number of patents on the technology. His arguments mentioned appliance flexes a lot. 

    So I am skeptical about the benefit of AFDDs in installations complying with BS7671 without AFDDs and I feel that we should have been given the statistics that prove the benefits of AFDDs before they were introduced into the standard

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  • 0

    When they were first introduced in the wiring regs I did some research.

    All the statistics I could find in America assumed that all electrical fires were caused by Arc faults and I could not see a correlation between the introduction of AFDDs and a decrease in electrical fires.  This exercise was made more difficult by the individual states using different terminology and collecting different statistics. Bear in mind that America used to use a lot of aluminium cable in house wiring  and the outlets are not fused. 

    Digging deeper I found papers by an safety conscious American electrical engineer, who's name I cannot remember, who started out writing papers and having meetings with electrical distributors where he was trying to get them to install fuses at the house end of distributers cables. He was also trying to get the MCBs used in consumer units to be made more sensitive, from what I read the MCBs used at the time were similar to our D types. He then started on Arc fault detection having been involved in the examination of a number of electrical fires and I believe had a number of patents on the technology. His arguments mentioned appliance flexes a lot. 

    So I am skeptical about the benefit of AFDDs in installations complying with BS7671 without AFDDs and I feel that we should have been given the statistics that prove the benefits of AFDDs before they were introduced into the standard

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