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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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    Colin Jenkins:

    Hello Chris.

    It's something I picked up several years back when I was reading the specs and experience of AFDDS in the USA vs UK, but I must admit I can't find that first-hand now.

    AFDDs for sale in the UK must comply with BS EN 62606.  I haven't got access to that, but Schneider have a technical description of their AFDDs with respect to BS EN 62606 and this refers to the requirement that an AFDD must trip in 1 second at 2.5 amps.


    I asked because I think that the generation of myths should be avoided. BS EN 62606:2013+1 does not, as far as I can see, specify a threshold.


    Here is table 1 from the BS - maximum break time against test arc current


    2,5 A     5 A    10 A     16 A     32 A    63 A

     1,0 s  0,5 s  0,25 s  0,15 s  0,12 s  0.12 s


    That they must trip within 1.0 s at 2.5 A does not mean that do not at lower currents, but I think that one could infer that they need not do so. Certainly, I don't think that one could rely on them tripping significantly lower than 2.5 A.


    Interestingly Schneider say: "a series arc is dangerous as soon as its value equals or exceeds 2.5 Amps".


    It may be that a lighting circuit feeds only fixed luminaires whose total consumption is < 2.5 A in which case AFDD would be pointless; but as soon as you have lamp-holders, it would be difficult to be sure.


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  • 0
    Colin Jenkins:

    Hello Chris.

    It's something I picked up several years back when I was reading the specs and experience of AFDDS in the USA vs UK, but I must admit I can't find that first-hand now.

    AFDDs for sale in the UK must comply with BS EN 62606.  I haven't got access to that, but Schneider have a technical description of their AFDDs with respect to BS EN 62606 and this refers to the requirement that an AFDD must trip in 1 second at 2.5 amps.


    I asked because I think that the generation of myths should be avoided. BS EN 62606:2013+1 does not, as far as I can see, specify a threshold.


    Here is table 1 from the BS - maximum break time against test arc current


    2,5 A     5 A    10 A     16 A     32 A    63 A

     1,0 s  0,5 s  0,25 s  0,15 s  0,12 s  0.12 s


    That they must trip within 1.0 s at 2.5 A does not mean that do not at lower currents, but I think that one could infer that they need not do so. Certainly, I don't think that one could rely on them tripping significantly lower than 2.5 A.


    Interestingly Schneider say: "a series arc is dangerous as soon as its value equals or exceeds 2.5 Amps".


    It may be that a lighting circuit feeds only fixed luminaires whose total consumption is < 2.5 A in which case AFDD would be pointless; but as soon as you have lamp-holders, it would be difficult to be sure.


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