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New single module AFDD RCBO

Sparkingchip
Crabtree mini-AFDD


Game changer or not?


Andy Betteridge
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    Game changer or not?



    I guess it depends mainly on the price.
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    Also, it might be more helpful if it actually works!

    Not that there is much empirical evidence that the thing is actually needed at all.
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    and does it break both poles or just one and leave the N still connected?
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    I fitted a few Crabtree consumer units twenty years ago, but there were the two designs in use and even then you could not get replacement RCDs for the earlier versions. Plus I had to drive quite a long way to replace a couple of failed MCBs.


    So I stopped using them and have not fitted a Crabtree CU since then, so after twenty years I need to be brought back on side.


    I presume these are not actually made in the same factory by the same people as those old consumer units and devices of twenty years ago, so need to be considered as a completely different product designed to be installed in a similar way being plugged into the busbar.


    I do wonder how much back compatibility there is?


    Andy Betteridge 

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    I wonder if it is all packaged in a single module how tall is it? Also the price? I see in the Screfix catalogue a double module Wylex a combined MCB, RCBO and AFDD is listed at £204.79 each!


    I would be interested in forum members views on whether AFDD protection is needed on 30mA RCD protected circuits where the CPC is in close contact with the insulation on the live conductors such as T &E and FP200 cables? Would not the 30mA RCD operate far in advance of an AFDD if there was thermal damage to the conductor insulation?
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    John Peckham:

    I would be interested in forum members views on whether AFDD protection is needed on 30mA RCD protected circuits where the CPC is in close contact with the insulation on the live conductors such as T &E and FP200 cables? Would not the 30mA RCD operate far in advance of an AFDD if there was thermal damage to the conductor insulation?




    I assume (hope) that the AFDD (if it works) is protecting more than just breaks in the fixed wiring: loose terminals, faulty equipment etc.

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    Sparkingchip:

    I fitted a few Crabtree consumer units twenty years ago, but there were the two designs in use and even then you could not get replacement RCDs for the earlier versions. Plus I had to drive quite a long way to replace a couple of failed MCBs.


    So I stopped using them and have not fitted a Crabtree CU since then, so after twenty years I need to be brought back on side.


    I presume these are not actually made in the same factory by the same people as those old consumer units and devices of twenty years ago, so need to be considered as a completely different product designed to be installed in a similar way being plugged into the busbar.


    I do wonder how much back compatibility there is?


    Andy Betteridge 

     




    Crabtree is now owned by Siemens, its just a re-branded Siemens unit so should be better now. If it costs less than £120 I'd be surprised 

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    I would be interested in forum members views on whether AFDD protection is needed on 30mA RCD protected circuits where the CPC is in close contact with the insulation on the live conductors such as T &E and FP200 cables? Would not the 30mA RCD operate far in advance of an AFDD if there was thermal damage to the conductor insulation?



    T&E and thermal damage, I'd agree that the chances are that the RCD would trip.


    With mechanical damage though - e.g. screw or nail (esp if later partially removed) clipping the side of the cable and damaging one of the outer conductors alone - possibly less likely.


    Likewise for (loose) connections made in insulating enclosures.


    If would have thought that 'all round' earthing - e.g, BS 8436 cables and metal-clad accessories would have been a more reliable in that respect. Probably need all class I appliances then too though.


      - Andy.

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    Curious - is there no button marked "T" or "Test" for the RCD element?

      - Andy.
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    Well spotted. It rather seems you cannot test the AFD part, so perhaps the same liberal approach has been extended to the whole design.

    Perhaps they realise no-one tests RCDs either.  (?)

    Joking aside I agree it seems odd, perhaps this is a marketing graphics thing, I have not seen one for real.

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